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Author Topic: Electrical ground fault and ground locations  (Read 11180 times)

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demolite

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Electrical ground fault and ground locations
« on: 24 April 2016, 13:01:58 »

I recently purchased a facelift Omega with the 2.5 V6 engine that had several garages look at it, change parts, rebuild the engine and finally deem it a lost cause. Repair costs were in the thousands.

The problem?

Bad ground to ECU which caused a voltage of 0.5 V at the ECU ground terminals. This caused the lambda signals to shift down by the same 0.5 V and show "lean" almost all the time resulting in an over rich fuel mixture and poor running. So beware, this is where the level of troubleshooting abilities have come to at some garages, even at the dealer!

I currently have additional ground wires running from the ECU to the engine and lambdas, but would like to find the "real problem". Being that the V6 engine bay is pretty full, I can't seem to locate all the main grounding points. I belive the (only?) chassis ground is below the battery as one of the battery negative cables runs there. The engine ground is located on the right side of the engine but where exactly and how can it be reached? And finally the culprit, the ECU ground, I'm thinking connected to engine but couldn't find it.

Thanks in advance!
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zirk

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Re: Electrical ground fault and ground locations
« Reply #1 on: 25 April 2016, 12:20:02 »

The Lamdda's have there own earth return (on Non DBW its shared between heater and sensor) as well as earth return through the outside of the Lambda itself which is earthed through the Exhaust via engine etc, so could be worth checking the lambda Sensor Loom connections as well as the main Engine / Battery earth straps.
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demolite

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Re: Electrical ground fault and ground locations
« Reply #2 on: 25 April 2016, 20:43:43 »

As far as I know, standard 3-wire lambda sensors don't use the heater return for earthing purposes. The only earth path is through the exhaust pipe and manifold to the engine. DBW models use 4-wire lambda sensors which have a seperate earth wire for the signal.

The wiring diagrams I have don't specify main earthing points. Is the ECU earthed on the chassis or the engine, and where is this connection?

 
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terry paget

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Re: Electrical ground fault and ground locations
« Reply #3 on: 25 April 2016, 21:36:39 »

I'm amazed they thought it worth while to rebuild the engine; fault is clearly electrical. Was there really 0.5 volts between engine and battery negative terminal? If so it could simply be corrected with an earth strap between battery negative terminal and engine. 2.5 is not drive by wire.
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demolite

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Re: Electrical ground fault and ground locations
« Reply #4 on: 25 April 2016, 23:22:26 »

Not exactly between the engine and battery, but battery negative and ECU earth terminals (I measured on terminals 2, 14 and 24). All were about 0.15 volts when ignition was on and jumped to over 0.5 volts when engine was running (due to increased return current). There is some extra resistance in the ECU earth wire bundle connection (Can't test yet because I don't know where the connection is). 

And yes they did rebuild it, from the block up. The notes on the receipts state that after the dealer had plugged in a Tech 2, it showed various faults for both lambda sensors. They changed both sensors for original ones (I would guess without even measuring the old ones). This didn't help so they deemed it must be a fault in combustion. On to the next garage for a second opinion. They reached a similar conclusion after trying new lambdas and fitting an aftermarket MAF >:(. They then rebuilt the top of the engine. Didn't help so back to the dealer. They suspected that timing was off after the rebuild but it wasn't. ECU was sent for repair, no problems there. They tried new lambdas. Nope. On to the next garage. They again CHANGED THE LAMBDAS and fit new oem catalytic converters for a sum that makes me cry. Surprisingly it didn't work so the owner gave up and sold it as faulty. I'm sorry for the previous owner who had to pay for "the ride".

When I got the car, it ran poorly. It used insane amounts of petrol and was low on power. I started troubleshooting, changed the aftermarket MAF for a used genuine one, got a diagnostic tool and did basic maintenance. The diagnostic tool told me the same things Tech 2 told the dealer. It showed me that both lambdas were registering a lean mixture and errors 13, 73, 74 and 89 were registered. I measured the lambdas directly from the sensor itself and they both showed over 0.8 volts on warm engine idle, which means pretty rich. ECU diagnostic on the other hand stated that both lambdas output only about 0.3 volts. Then it was a few voltage drop measurements here and there to find the problem.

To be clear, the car runs perfectly now with the additional earth wires I put in myself. I just want to fix the old earth wiring to tidy up the engine bay. My questions are:

Where is the engine earth wire connected on the 2.5 V6 engine?
Where do the small brown wires from ECU earth terminals go?
Is the earth terminal below the battery the only main earth terminal for the car chassis?
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jimbo125

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Re: Electrical ground fault and ground locations
« Reply #5 on: 26 April 2016, 00:15:16 »

Just rebuilt top end on mine and did some earth tidying up, one main earth terminal under the battery tray, one by the A/C compressor on the right hand side of the engine crankcase and most difficult to get to are the three brown earth wires at the back of the number two head next to the DIS module, just fitted mine what a sod. Hope this helps :y
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terry paget

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Re: Electrical ground fault and ground locations
« Reply #6 on: 27 April 2016, 12:02:41 »

Congratulations to you, demolite. It seems obvious now, but it clearly was not to the dealer and other garages. You win the prize of a cheap motor car, plus the satisfaction of succeeding where others have failed. I have suffered strange consequences of bad earth connections on old cars, but never engine related.

Last time I enquired about the cost of Vauxhall Omega catalysts, it was about £1000. And the previous owner fitted two, on a car worth £400. I imagine he is vexed.
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Kevin Wood

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Re: Electrical ground fault and ground locations
« Reply #7 on: 27 April 2016, 13:13:33 »

This story just goes to show how daft the path of "diagnosis by substitution of parts" can become. ;D

My bet is that the ECU ground wires lead to the connection at the rear of the cylinder heads and that this earth wasn't reinstated after the first engine rebuild! GM would have been conscious of the need to prevent any voltage drop in the lambda circuits so a connection to the heads is a no-brainer.
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Nick W

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Re: Electrical ground fault and ground locations
« Reply #8 on: 27 April 2016, 13:24:32 »

This story just goes to show how daft the path of "diagnosis by substitution of parts" can become. ;D



There's also the common assumption that it's going to be the most complicated part that has gone wrong. How many times have you heard that 'carbs knackered, I've done everything' for a car that won't start, and yet methodical diagnosis instantly shows that there is no spark? That's happened to me so often that I always start with the ignition, as it's easiest to prove.
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Kevin Wood

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Re: Electrical ground fault and ground locations
« Reply #9 on: 27 April 2016, 14:17:00 »

This story just goes to show how daft the path of "diagnosis by substitution of parts" can become. ;D



There's also the common assumption that it's going to be the most complicated part that has gone wrong. How many times have you heard that 'carbs knackered, I've done everything' for a car that won't start, and yet methodical diagnosis instantly shows that there is no spark? That's happened to me so often that I always start with the ignition, as it's easiest to prove.

Yes, that's true. "That complicated thing with all the pipes / wires* that I don't understand and which therefore uses witchcraft. It'll be that.". ::)

* - Delete as appropriate
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Marks DTM Calib

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Re: Electrical ground fault and ground locations
« Reply #10 on: 27 April 2016, 14:37:13 »

Main engine ground to battery is on the PAS/Aircon bracket

All signal and ECU grounds are on the DIS pack bracket (three off) at the rear of the 2-4-6 cylinder head,
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tigers_gonads

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Re: Electrical ground fault and ground locations
« Reply #11 on: 27 April 2016, 15:36:23 »

Main engine ground to battery is on the PAS/Aircon bracket

All signal and ECU grounds are on the DIS pack bracket (three off) at the rear of the 2-4-6 cylinder head,




Yup
If this bonding strip is broken, experience tells me  :-[ that you will loose at least 0.8 volt at idle if measured across the battery terminals  ;)
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terry paget

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Re: Electrical ground fault and ground locations
« Reply #12 on: 27 April 2016, 16:13:16 »

This story just goes to show how daft the path of "diagnosis by substitution of parts" can become. ;D



There's also the common assumption that it's going to be the most complicated part that has gone wrong. How many times have you heard that 'carbs knackered, I've done everything' for a car that won't start, and yet methodical diagnosis instantly shows that there is no spark? That's happened to me so often that I always start with the ignition, as it's easiest to prove.
Followed by whipping off fuel feed pipe and checking there is fuel feed.
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demolite

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Re: Electrical ground fault and ground locations
« Reply #13 on: 27 April 2016, 19:16:04 »

Thanks everyone for your help.

I'll get on to fixing the old grounds and cables. I'll take pictures and maybe write a guide on how to measure and repair the important grounds. It might be of help to someone else having persistant issues with fuel consumption and faults.
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terry paget

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Re: Electrical ground fault and ground locations
« Reply #14 on: 27 April 2016, 20:46:00 »

Reading google, with zirconia lambda sensors, centre wire +0.1v above ground is very lean, 0.5v about right (stoichometric), and 0.9v very rich. But when ECU ground is +0.5v above ground when mixture is right and lambda is 0.5v above local earth it will be 0.0v above ECU earth. ECU thinks mixture very lean so injects more fuel, when engine is very rich and lambda +0.9v ECU reads this as +0.4v and injects even more fuel. Engine runs very badly, drinks fuel and exhaust probably smells of it.

Well rumbled, demolite. You have taught me a lot.

In an MOT emission test, the meters display CO, HC, and Lambda. Limits are CO =<0.2%, HC =<200ppm and lambda between 0.97 and 1.03. What does the lambda measurement mean?
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demolite

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Re: Electrical ground fault and ground locations
« Reply #15 on: 27 April 2016, 22:44:21 »

In an MOT emission test, the meters display CO, HC, and Lambda. Limits are CO =<0.2%, HC =<200ppm and lambda between 0.97 and 1.03. What does the lambda measurement mean?

It's a calculated residual oxygen factor. It tries to determine if engine is running on average a stoichometric mixture. Because of the catalytic converter, this value is only mathematical. Air leaks and such might skew this value.
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demolite

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Re: Electrical ground fault and ground locations
« Reply #16 on: 12 May 2016, 21:31:48 »

I finally fixed the ECU grounds. The three small bolts holding the three ground wires to the dispack tray were dirty and only finger tight! Good news is, lambdas work nicely now and voltage goes to 800+ mV when accellerating.

Bad news is I broke something. I removed the scuttle and the two small vacuum pipes from the brake booster line for more access. Cleaned the grounds and then assembled all back.

When warm, the engine runs fine but cold starts became very poor. This happened right after fixing the grounds, so I guess I must have done something by accident.

Symptoms are:

- Very rich fuel mixture on cold start (outdoor temp 20 celcius)for about a minute (can see it on my MID as up to 10L/h and very strong petrol smell around car (this used to be about 4L/h))
- Diagnostic tool shows air consumption as 40kg/h during this time -> can anybody verify?
- Fuel trim for banks 1 and 2 differ about 30% on idle, about 4% on part load. Bank 1 seems to run very near normal trim, bank 2 is the one that needs much more. (These can be the other way around as diagnostic tool is inconsistent) 

Was thinking of a serious vacuum leak but couldn't find one... Any help?
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Andy H

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Re: Electrical ground fault and ground locations
« Reply #17 on: 12 May 2016, 21:40:20 »

I finally fixed the ECU grounds. The three small bolts holding the three ground wires to the dispack tray were dirty and only finger tight! Good news is, lambdas work nicely now and voltage goes to 800+ mV when accellerating.

Bad news is I broke something. I removed the scuttle and the two small vacuum pipes from the brake booster line for more access. Cleaned the grounds and then assembled all back.

When warm, the engine runs fine but cold starts became very poor. This happened right after fixing the grounds, so I guess I must have done something by accident.

Symptoms are:

- Very rich fuel mixture on cold start (outdoor temp 20 celcius)for about a minute (can see it on my MID as up to 10L/h and very strong petrol smell around car (this used to be about 4L/h))
- Diagnostic tool shows air consumption as 40kg/h during this time -> can anybody verify?
- Fuel trim for banks 1 and 2 differ about 30% on idle, about 4% on part load. Bank 1 seems to run very near normal trim, bank 2 is the one that needs much more. (These can be the other way around as diagnostic tool is inconsistent) 

Was thinking of a serious vacuum leak but couldn't find one... Any help?
Have you cleared the long term fuel trims?
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demolite

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Re: Electrical ground fault and ground locations
« Reply #18 on: 12 May 2016, 21:49:51 »

Have you cleared the long term fuel trims?

Yes I've cleared all learned values after the repair a few times. Trims become like stated earlier over a few days. Start problem is even with all trims zeroed.
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Kevin Wood

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Re: Electrical ground fault and ground locations
« Reply #19 on: 20 May 2016, 00:20:57 »

Coolant temperature sensor is round the back on the coolant bridge. I wonder if you dislodged the connector to it?

That would explain poor cold starting.
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demolite

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Re: Electrical ground fault and ground locations
« Reply #20 on: 20 May 2016, 11:38:21 »

I've been getting to the bottom of this.

Idle BLM values skyrocketed after I reconnected the grounds. The other value hit 255 while the other was a little over 200.
Engine seems to use the learned idle BLM value for cold starts and 700-1200 rpm idle. When its 255 (+100%) theres a lot extra fuel when the vacuum was leaking less (at higher idle).


It seems that the bad grounds were masking a problem with the fuel vapor solenoid beign stuck open. Thats why no vacuum leak was found, it was sucking air from the canister. I'm testing it now with the fuel vapor hose disconnected from the breather and the port blocked. Looks good, BLM values are staying in the low 140's, and no fuel smell anymore. The automatic gearbox does actually engine brake a lot better now, cant say about fuel consumption yet.
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mandula

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Re: Electrical ground fault and ground locations
« Reply #21 on: 07 June 2016, 20:32:41 »

Hi,

I've got fault code P0130(4) for awhile now, always not present and cleared it, and it keeps coming back.
I replaced 1st lambda, but still the same. ECU casing is grounded via extra cable to battery ground terminal.

I was looking livedata of 1st lambda, and noticed voltage won't rise even above 700 mV, just jumps between 50 - 650 mV.
I think that is too low (is it?).

I read that it could also be ECU fault, but now I spotted this topic. Will check groundings soon, but what do you think, could this just be ground fault?

Here is some livedata from semi-warm motor running idle:
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demolite

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Re: Electrical ground fault and ground locations
« Reply #22 on: 07 June 2016, 22:22:27 »

Based on the data, I'd say there could be some some voltage drop on the B1S1 circuit, but the O2 seems to be switching normally albeit maybe a little on the slow side. You are right, the 650mV is too low a maximum for a fully working circuit. What happens when you accelerate hard? 650 mV again or more? Accellerating hard takes the system to richer open loop settings and this way you can test if the O2 can generate more voltage, and if it gets to the ECU.

I take it from the OBD2 code you're getting that you have a facelift model with the 2.2 engine? On these engines, the O2's are 4 wire (instead of older 3 wire), and dont use the exhaust and engine block as a ground return path. They physically can't suffer from the same type of ground voltage problems like the older 2.0, 2.5 and 3.0 engines if the wiring is still connected as the manufacturer intended (a 4 wire sensor is used and connected to original 4 wires to O2). Bad ground tends to shift the readings down, and I saw a value of 0 mV (as it went negative) often from my O2.

There could be problems on the O2 wires if someone has connected them wrongly (signal ground and heater ground switched or connected together) or grounded a O2 signal ground wire on the first O2. Also check for high resistance on the signal wire, connectors and signal ground wire.

Be sure to check the O2 heater circuit for problems as well, as a cool O2 will switch slowly and can generate lower voltages. If you need any help making any measurements, I'll be glad to help.


Just a thought..
There could also be problems with stray current through the ECU casing (due to the extra grounding), causing voltage drop inside the ECU. Ecu on the 2.2 is normally grounded (according to wiring diagram) at the  chassis point below the battery. Grounding the case to the battery terminal could theoretically make current run from

the chassis point -> the ecu ground wire -> the inside of the ecu -> the case -> the battery

causing voltage drops in its internal ground plane. Try disconnecting the extra ground.   
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mandula

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Re: Electrical ground fault and ground locations
« Reply #23 on: 08 June 2016, 20:35:35 »

Thanks for your very informatic reply!

I have Z22XE engine with original wirings from ECU to lambda, my new lambda required to cut old lambda connector to be attached to new one. Colors matched on wires so I think no problem there.

I removed extra grounding from ECU casing, stil the same with engine idling.

However, when I revved up to 2000 rpm and above, I noticed first that 1st lambda voltage dropped almost to zero and stay very low, at the same time before closed lambda loop changed to open loop and 1st lambda did not make any sense. Voltage commonly stay low but some times got up to 500 to 600 mV and then dropped down again. 2nd lambda started to show high readings, 500 to 600 mV at revs.

When I got back to idle, lambda loop stay open and 1st lambda at zero or little higher.

I think that is what causes the fault code.

I could not yet get data to chart, because excel got confused for thousands on RPM data are separated with space, I'll try to get it sorted out so you can get better idea whats going on.
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Re: Electrical ground fault and ground locations
« Reply #24 on: 08 June 2016, 21:58:16 »

Thanks for your very informatic reply!

I have Z22XE engine with original wirings from ECU to lambda, my new lambda required to cut old lambda connector to be attached to new one. Colors matched on wires so I think no problem there.

I removed extra grounding from ECU casing, stil the same with engine idling.

However, when I revved up to 2000 rpm and above, I noticed first that 1st lambda voltage dropped almost to zero and stay very low, at the same time before closed lambda loop changed to open loop and 1st lambda did not make any sense. Voltage commonly stay low but some times got up to 500 to 600 mV and then dropped down again. 2nd lambda started to show high readings, 500 to 600 mV at revs.

When I got back to idle, lambda loop stay open and 1st lambda at zero or little higher.

I think that is what causes the fault code.

I could not yet get data to chart, because excel got confused for thousands on RPM data are separated with space, I'll try to get it sorted out so you can get better idea whats going on.
Worth checking that they used the same colours........
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demolite

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Re: Electrical ground fault and ground locations
« Reply #25 on: 08 June 2016, 23:57:43 »

Try to get a reading with the engine worked hard, as in open loop and running rich. Also if you can, measure the O2 signal wires directly at the connector (preferably at the sensor connector). This way you can see if there is voltage drop to the ECU on either the signal or the ground line. The sensor should be connected while doing this; you can use sharp long needles to backprobe the connector. When letting off the gas, low voltage is typical, but on high steady revs, it should be switching in the 100 - 900mV range. How's the car running at high revs? Do you have an exhaust leak?

I counted the O2 cycles on your diagram and got 16 cycles (450 mV to highest value then to lowest value and back to 450mV) in 100 seconds. That is very slow, a new sensor should cycle about once in 1-2 sec, although this is dependant on the ECU too. On my 2.5 both sensors cycle about 20 times a minute at idle, 40+ times a minute at 2000 rpm. What are your short term and long term fuel trim values? Better yet, can you include them in the next graph?

new lambda required to cut old lambda connector to be attached to new one

Attached how? Some sensors have an outside oxygen reference path inside the signal or ground wire (oxygen molecules move between copper strands). Although this is not true for all O2 sensors, I suggest they shouldn't be soldered for this reason. I have never seen one fail if soldered, but there is a chance.

Based on the slow switching and low voltage there is a possibility that the sensor is bad. Even new ones can fail, some already at the factory.

I don't want to believe the fault is with the ECU, they are usually pretty robust.
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Re: Electrical ground fault and ground locations
« Reply #26 on: 09 June 2016, 07:01:46 »

Here's some graphs, hope it makes sense..


RPM - lambda 1 & 2 - fuel trim - O2 loop (open/closed)
Cold start, waited for idle to settle and then revved couple of times.


RPM - fuel trim
Detailed view from above graph.

I have equipments to measure 1st lambda from connector, hope I have time to do that maybe tomorrow.


About lambda connection: new lambda is Delphi make, it had this kind of connectors on all four wires [link].

I cut old lambdas wires near its connector and attached this old lambda connector to new lambda, color to color. There was two whites, one brown and one black (if I remember right).


I don't notice anything abnormal when idling or revving the engine, no shaking or misfire-kind feelings. Idle consumption stays at 1,1 - 1,2 l/h (AC off), average cons. about 8,5-9,5 l/100km. Usual cold start idle consumption starts from 5 l/h and may take couple of minutes to drop to normal level. Gasoline does not smell out of exhaust gasses when hot engine, only at cold starts but not very noticeable.

Exhaust flex pipe replaced one year ago, also whole pipe from cats back. I haven't check condition of exhaust manifold, will do that tomorrow.

There is one thing that has troubled me for awhile: You can see from above graph that there is that period of time from cold start that idle is high and is settling down. Sometimes that idle is even higher than shown in graph (even up to 3000 rpm), and if I rev up the engine or start driving, revs can get "stuck" up, lets say if I rev up to 2500 rpm and release acc pedal, revs stay 2500 until drops after 10-20 seconds.
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Re: Electrical ground fault and ground locations
« Reply #27 on: 09 June 2016, 23:36:30 »

Something weird going on at 270 seconds on the first graph, just as you give it that last touch of gas before letting off. Looks to me like O2 sensor was disconnected at that point. Ecu notes fault and goes open loop. O2 signal comes back at about 290 seconds, ecu stays in open loop because it takes time to start "trusting" the O2 again.

Some theory on my deduction:

Ecu's use a bias voltage on the circuit to determine if O2 sensors are connected, working and are at operating temperature (they are producing voltage). A bias voltage means that an outside voltage is inserted into a signal to bring it to some level in case the signal is very weak. This bias voltage for narrowband zirconia O2 sensors is pretty much always around 450 mV, and the ecu feeds it into the signal path through a resistor. Why this voltage? A narrowband O2 sensor will produce this voltage only under a VERY tiny window of exhaust oxygen concentration. So tiny, that producing such a concentration for any prolonged amount of time is impossible with an engine. (Catalytic converter can produce this voltage for some seconds, see B1S2) For the engine O2, if the sensor voltage is in the area of 420-480 mV for over a few hundred milliseconds the ECU knows this voltage can't be from the O2 sensor but from its own biasing circuit; the sensor is disconnected, not at operating temperature or broken. I'm willing to bet that this situation is what's causing the fault code. The biasing voltage can be seen at cold sensor 0-20 s and possible disconnected/poor contact sensor at 270-290 s.

The disconnection could be caused by engine vibration inside the sensor itself, in the connectors, wires or inside the ecu. Bad contact (high resistance) is a likely culprit. Would also explain shifted low values.

By the way, there was a bulletin from Opel/Vauxhall on ecu's that had wrong kind of protection grease put on the ecu connectors at the factory. This caused poor connections in the ecu connector on some pins after many years from manufacture. Sorry I don't remember which year it was but doesn't hurt to check.
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Re: Electrical ground fault and ground locations
« Reply #28 on: 10 June 2016, 07:34:58 »

Thanks again for nice reply!

I doubt that lambda itself is faulty, because fault code did not disappear or change since I replaced it.

Can you tell witch pins on ECU should I measure between lamda connector and ECU?

Today I plan to measure wirings, clean groundings and ECU connectors and check lambda wirings.
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Re: Electrical ground fault and ground locations
« Reply #29 on: 10 June 2016, 09:51:34 »

My recollection is that the 4 pot Omegas use Titania Lambda sensors not the more common Zirconia devices as used on the V6s. This means they have different characteristics so you can't directly compare the output voltages. If it 'ain't broke... ;)
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Re: Electrical ground fault and ground locations
« Reply #30 on: 10 June 2016, 10:11:45 »

My recollection is that the 4 pot Omegas use Titania Lambda sensors not the more common Zirconia devices as used on the V6s. This means they have different characteristics so you can't directly compare the output voltages. If it 'ain't broke... ;)

Is that so? If Z22XE uses Titania-type lambda then there is my problem, because now I have Zirconia-type..
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Re: Electrical ground fault and ground locations
« Reply #31 on: 10 June 2016, 10:30:59 »

My recollection is that the 4 pot Omegas use Titania Lambda sensors not the more common Zirconia devices as used on the V6s. This means they have different characteristics so you can't directly compare the output voltages. If it 'ain't broke... ;)


I don't believe that is true for 2.2 liter engines. Based on the graph the ecu clearly biases the circuit at 450 mV, typical for zirconia (vs. ~2v vor titania). Also sensor B1S2 is your typical zirconia too.Some of the 2.0 liter engines do have titania.


For Z22XE/Y22XE engine model:

ECU CONN. X83         WIRE COLOR          B1S1 CONN.
8                             gray                     4   (signal ground)
57                            black                    2  (signal)
19 & 35                     brown-white          1  (heater ground)               
23                 red-blue@ecu/white@O2     3  (heater power)

I can't tell which of the two ecu connectors is X83, try the one with more wires going to it...
Fault is intermittant so wiggle the wires as you test!

Edit: I corrected the signal ground and signal wire color & number.
« Last Edit: 10 June 2016, 10:42:26 by demolite »
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Re: Electrical ground fault and ground locations
« Reply #32 on: 10 June 2016, 11:34:11 »

My recollection is that the 4 pot Omegas use Titania Lambda sensors not the more common Zirconia devices as used on the V6s. This means they have different characteristics so you can't directly compare the output voltages. If it 'ain't broke... ;)


I don't believe that is true for 2.2 liter engines. Based on the graph the ecu clearly biases the circuit at 450 mV, typical for zirconia (vs. ~2v vor titania). Also sensor B1S2 is your typical zirconia too.Some of the 2.0 liter engines do have titania.


For Z22XE/Y22XE engine model:

ECU CONN. X83         WIRE COLOR          B1S1 CONN.
8                             gray                     4   (signal ground)
57                            black                    2  (signal)
19 & 35                     brown-white          1  (heater ground)               
23                 red-blue@ecu/white@O2     3  (heater power)

I can't tell which of the two ecu connectors is X83, try the one with more wires going to it...
Fault is intermittant so wiggle the wires as you test!

Edit: I corrected the signal ground and signal wire color & number.

Thanks for this. Will report back if I found anything wrong.
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Re: Electrical ground fault and ground locations
« Reply #33 on: 11 June 2016, 12:17:45 »

I made some basic measurements, dont have much time to go through ECU to lambda wirings.

Power off there was no resistant or voltage loss when compared between battery terminals and ECU casing.

But when idling the engine, there was resistant of 40 ohms between battery ground terminal and ECU casing and 0.06 V loss between battery plus and ECU chasing.

Also there was resistant of 100 ohms between engine block and battery ground terminal and same with ECU casing and engine block while idling. Powers off resistant was about 30 ohms.

So it seems that at least I need to clean all grounding points. I can see where ECU and some others ground below fuse box, but battery grounding to engine is not so clear to see. It dives somewhere under AC compressor,,can I reach it from below?

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Re: Electrical ground fault and ground locations
« Reply #34 on: 11 June 2016, 13:54:21 »

I made some basic measurements, dont have much time to go through ECU to lambda wirings.

Power off there was no resistant or voltage loss when compared between battery terminals and ECU casing.

But when idling the engine, there was resistant of 40 ohms between battery ground terminal and ECU casing and 0.06 V loss between battery plus and ECU chasing.

Also there was resistant of 100 ohms between engine block and battery ground terminal and same with ECU casing and engine block while idling. Powers off resistant was about 30 ohms.

So it seems that at least I need to clean all grounding points. I can see where ECU and some others ground below fuse box, but battery grounding to engine is not so clear to see. It dives somewhere under AC compressor,,can I reach it from below?
Your multi-meter will contain a small battery (probably 9 Volts). During resistance measurement your meter will pass a small current through the component being measured and measure a very small voltage drop to calculate resistance. If any additional current passes through the component on test then the reading will be meaningless.

When the engine is running the alternator will be charging the battery. The maximum output of the alternator is 140 Amps - your meter probably uses a current of between 0.01 and 0.1 Amps for resistance measurement so you risk frying your multimeter if you try to measure the resistance of the earth strap when the engine is running.

What would be more useful would be to measure the voltage difference between the block and the battery terminal with the engine running.
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Re: Electrical ground fault and ground locations
« Reply #35 on: 11 June 2016, 15:05:47 »

I made some basic measurements, dont have much time to go through ECU to lambda wirings.

Power off there was no resistant or voltage loss when compared between battery terminals and ECU casing.

But when idling the engine, there was resistant of 40 ohms between battery ground terminal and ECU casing and 0.06 V loss between battery plus and ECU chasing.

Also there was resistant of 100 ohms between engine block and battery ground terminal and same with ECU casing and engine block while idling. Powers off resistant was about 30 ohms.

So it seems that at least I need to clean all grounding points. I can see where ECU and some others ground below fuse box, but battery grounding to engine is not so clear to see. It dives somewhere under AC compressor,,can I reach it from below?
Your multi-meter will contain a small battery (probably 9 Volts). During resistance measurement your meter will pass a small current through the component being measured and measure a very small voltage drop to calculate resistance. If any additional current passes through the component on test then the reading will be meaningless.

When the engine is running the alternator will be charging the battery. The maximum output of the alternator is 140 Amps - your meter probably uses a current of between 0.01 and 0.1 Amps for resistance measurement so you risk frying your multimeter if you try to measure the resistance of the earth strap when the engine is running.

What would be more useful would be to measure the voltage difference between the block and the battery terminal with the engine running.

This. Voltage measurements between all major grounds with the engine running. You would need to disconnect the battery and use a milliohm-meter to measure it accurately otherwise.
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Re: Electrical ground fault and ground locations
« Reply #36 on: 11 June 2016, 17:42:54 »

Something I don't think I have seen mentioned in this thread is the importance of keeping some earth paths separated.

Some devices just need a big stupid earth wire because they draw a lot of current but they don't really care if there is a largish volt drop (think starter motor cranking a cold engine). Others don't pass much (or any) current but the earth wire is required for a zero voltage reference.

The lambda sensor is two devices in one case. There is a big stupid heater element which needs a big stupid earth wire. It doesn't matter whether this wire goes back to the block, or the bolt under the battery or to the battery terminal - these points are all at slightly differing voltages when the engine is running but not by enough to bother the heater. Then there is the lambda sensor itself which generates a tiny voltage and needs an earth wire which goes back to a zero voltage reference point in the ECU. If the heater earth wire and the lambda earth wire get swapped then the large current from the heater will pass through the circuit board inside the ECU and the sensitive circuitry which drives the lambda sensor will be using a different zero voltage reference to the lambda sensor.
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mandula

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Re: Electrical ground fault and ground locations
« Reply #37 on: 12 June 2016, 13:53:51 »

My recollection is that the 4 pot Omegas use Titania Lambda sensors not the more common Zirconia devices as used on the V6s. This means they have different characteristics so you can't directly compare the output voltages. If it 'ain't broke... ;)


I don't believe that is true for 2.2 liter engines. Based on the graph the ecu clearly biases the circuit at 450 mV, typical for zirconia (vs. ~2v vor titania). Also sensor B1S2 is your typical zirconia too.Some of the 2.0 liter engines do have titania.


For Z22XE/Y22XE engine model:

ECU CONN. X83         WIRE COLOR          B1S1 CONN.
8                             gray                     4   (signal ground)
57                            black                    2  (signal)
19 & 35                     brown-white          1  (heater ground)               
23                 red-blue@ecu/white@O2     3  (heater power)

I can't tell which of the two ecu connectors is X83, try the one with more wires going to it...
Fault is intermittant so wiggle the wires as you test!

Edit: I corrected the signal ground and signal wire color & number.

Okay, measured these.

No resistant between ECU connector and lambda connector corresponding wires, and no cuts when I shaked wirings during measurements. Also soldered the wirings together where old lamdbas connector and new lambda wirings are  attached.

Lambdas heater element resistant 4 ohms.

Signal ground no resistant to battery ground or ECU casing.

I think I try again with new genuine lambda tomorrow if that changes anything..
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Re: Electrical ground fault and ground locations
« Reply #38 on: 12 June 2016, 14:54:16 »

Ok, now I measured lambda voltage, does not rise above 500 mV even when throttling quickly. When keeping revs up voltage even drops near zero.

So could I say it is prety clear that new lambda would help on this matter..
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Re: Electrical ground fault and ground locations
« Reply #39 on: 12 June 2016, 16:48:37 »

Ok, now I measured lambda voltage, does not rise above 500 mV even when throttling quickly. When keeping revs up voltage even drops near zero.

So could I say it is prety clear that new lambda would help on this matter..

I now have replaced lambda with new same type and it kind of solved the problems.

No fault codes after replacement and driving 20 minutes on highway and in town.

It is just that voltage wont rise above 750 mV still (better than before 650 mV).

On highway voltage oscillated from 600-700 to 200-0 mV. In town it get as hogh as 750 mV when accelerating.

I think the main problem is that when I took closer look on package, it said that new lambda is universal type. What I'm read from Google is that universals dont necessary have the right voltage range as needed. And it mow seems that they can get broken also very fast  :(

I will buy genuine one, nevertheless no fault codes yet shown up. I will report back if this case is closed with genuine lambda.

Anyway, thanks for help guys/girls! This has teached me alot with this type troubleshooting and also some theory in this matter  :y
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Re: Electrical ground fault and ground locations
« Reply #40 on: 13 June 2016, 02:35:09 »

I wouldn't bother with an original part if the one you're now using works ok. Your lambda voltage goes high enough and isn't causing a fault. Try it for a few weeks.

The main problem with your old lambda was the abnormal activity of staying low (and going "disconnected") thus causing a fault code.

Universal sensors can work fine, and if you dont get the fault anymore, why spend more money?
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Re: Electrical ground fault and ground locations
« Reply #41 on: 13 June 2016, 04:43:54 »

I wouldn't bother with an original part if the one you're now using works ok. Your lambda voltage goes high enough and isn't causing a fault. Try it for a few weeks.

The main problem with your old lambda was the abnormal activity of staying low (and going "disconnected") thus causing a fault code.

Universal sensors can work fine, and if you dont get the fault anymore, why spend more money?

Just to be sure I don't need to do this same procedure again anymore ;)
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Re: Electrical ground fault and ground locations
« Reply #42 on: 13 June 2016, 15:41:01 »

Well, familiar fault code P0130 showed up again this morning, even lit the yellow engine fault light on dash. Quicky looked at live data and there was almost no voltage change on 1st lambda.

Replaced lambda with Bosch-style oem lambda and now I can see 1st lambda to oscillate nicely at idle from 0.1 to 0.8 V and on revs in faster cycles from 0 to almost 1.0 V.

Long term fuel trim was almost 10 %, do I need to reset that (I assume that is only doable with Tech2?), or do I just ignore it and let ot settle down by itself? Short term fuel trim showed on quick test 0 to -3 %.
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Re: Electrical ground fault and ground locations
« Reply #43 on: 13 June 2016, 17:14:41 »

My recollection is that the 4 pot Omegas use Titania Lambda sensors not the more common Zirconia devices as used on the V6s. This means they have different characteristics so you can't directly compare the output voltages. If it 'ain't broke... ;)


I don't believe that is true for 2.2 liter engines. Based on the graph the ecu clearly biases the circuit at 450 mV, typical for zirconia (vs. ~2v vor titania). Also sensor B1S2 is your typical zirconia too.Some of the 2.0 liter engines do have titania.


For Z22XE/Y22XE engine model:

ECU CONN. X83         WIRE COLOR          B1S1 CONN.
8                             gray                     4   (signal ground)
57                            black                    2  (signal)
19 & 35                     brown-white          1  (heater ground)               
23                 red-blue@ecu/white@O2     3  (heater power)

I can't tell which of the two ecu connectors is X83, try the one with more wires going to it...
Fault is intermittant so wiggle the wires as you test!

Edit: I corrected the signal ground and signal wire color & number.

You might be right, actually. It was the Simtec engine management on the X20XEV that used Titania.
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