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1

Omega General Help / Re: V6 cold start overfueling

« on: 17 November 2016, 15:59:41 »

Just an update in case anyone has the same problems. The fault was fixed with a new MAF sensor, but the old one could be resurrected too.

Just for fun I disassembled the old sensor to see whats inside.
A spider had made its home in the old one and some of the crud on the plate was too stubborn to get off with "maf cleaner" alone. So I mechanically cleaned it the best I could with isopropanol alcohol and q-tips and rags and it started working fine again! I tried it for a few weeks without any problems. So now I have a spare 

Heres what the insides looked like:


I think the crud and dirt caused some issues at low airflow in the cold.

2

Test Zone / Re: Cheap V6 crank locking tool

« on: 05 October 2016, 22:19:36 »

Yeah it can be modified easily, the point here was to warn that bad tools like this exist and to test pictures. 

3

Test Zone / Re: Cheap V6 crank locking tool

« on: 05 October 2016, 19:56:24 »

More pics. The tool was from a 50 euro ebay set.



Works fine without the screw.

4

Test Zone / Cheap V6 crank locking tool

« on: 04 October 2016, 19:31:44 »

Atleast some (I think all, but can someone confirm?) V6 engines have a crank sprocket where the bolt pattern is not uniform. This makes it impossible to install the aux belt pulley 180 degrees off.

See pic: (Upper thread hole is not in the center but about 4mm to the left of centerline)


Now I bought a crank locking tool set for doing the cambelt, and the crank tool didn't fit. Now I know why, here's the tools baseplate:


The hole which has the handscrew to screw to the upper sprocket thread is on the centerline of the tool! If it screws on, the tool is tilted and inaccurate. If you dont screw it on it won't go fully on the sprocket because the handscrew threads are in the way.


The tool can be used by removing the handscrew completely:


Needless to say, it has to be held on by hand when turning the crank.

5

Omega General Help / Re: V6 cold start overfueling

« on: 27 September 2016, 12:22:00 »

Everything is stock engine wise.

PFL MAFs are known to be 'bulletproof' this is most odd if this was the cause, and worth adding to our collective knowledge if this is the case.

Yeah, thats what i have read. I didn't even suspect it until it was one of the last possibilities. It wasn't fully broken but seems to give out of spec values when cold and/or at low airflow. No fault codes. Old and new are Bosch 0280217519. The surface of the measuring plate looks a bit oxidated.

I tried cleaning the MAF before replacement though.

6

Omega General Help / Re: V6 cold start overfueling

« on: 26 September 2016, 23:22:16 »

Just to let others know, the problem was a faulty MAF.

Tried another from the scrap yard and problems went away, cold starts now at about 3-4 l/h. It also hugely improved low end throttle response.

As to the negative spark timing, I found out from a Saab engineering manual that Bosch Motronic 2.8.1 uses multi-spark when the engine is cold (multiple ignition events per cylinder up to 12 degrees after TDC). The spark timing in diagnostic simply reports the last ignition event timing, which due to multiple ignitions can be negative (as in after TDC).

7

Omega General Help / Re: V6 cold start overfueling

« on: 11 September 2016, 15:28:27 »

Ecu coolant temp sensor

But it is reporting a plausible temperature in the diagnostic log, though might be a couple degrees off? (engine temp 17C, air temp 20C)

Ok

Being cabled throttle, how does the idle control valve behave?

The idle control valve was my first suspect but as far as I know it works fine. I've cleaned it multiple times to be sure and it works smoothly when tested with a variable power supply. Looking at the logs, the spark advance is very low and sometimes negative, but at the slightest touch of gas it goes to 10+ degrees advance. Spark retardation is usually a sign that the ECU tries to lower the rpm, but why?

8

Omega General Help / Re: V6 cold start overfueling

« on: 11 September 2016, 15:10:35 »

Ecu coolant temp sensor

But it is reporting a plausible temperature in the diagnostic log, though might be a couple degrees off? (engine temp 17C, air temp 20C)

9

Omega General Help / V6 cold start overfueling

« on: 11 September 2016, 13:46:52 »

Hi!

I've been tackling a problem with cold starts with my 2000 2.5 V6 (X25XE) facelift for some time now. Cold start here being any start at engine temperature of 30C or less. For the first 20-30 seconds the engine is overfueling and running rough and there's a strong smell of raw petrol in the cabin. This has happened on every cold start for atleast two months.

There are no fault codes, and the car runs fine for the rest of the day once the morning cold start is done with. There are no fuel leaks from the pipes, hoses, filter, pump assembly, injector rail, injectors, pressure test port or fuel pressure regulator. I ran the fuel pump for 30 minutes independent of engine with no fuel smell from anywhere (intake manifold was open to see injector leakage).

Typical start at ambient temperature 20C:
Upon starting, MID shows a fuel consumption of roughly 10 L/ hour which starts dropping slowly. Rpm is held at about 1300. About 3 seconds after start, engine starts running rough, fuel consumption is at 7-8 L/h. About 5 seconds after start strong fuel smell enters cabin, if car is creeping forward or stationary (smell coming from engine bay). It runs rough for about 20 seconds after this until the fuel consumption has dropped to about 4 L/h then suddenly engine smooths out. Fuel smell starts to fade and disappears in a matter of seconds. All is well for the rest of the day.

BUT, the engine smooths out instantly if the accellerator is pressed in any amount during rough running. Fuel consumption goes down when revs go up. Again if I let off the gas, the rough running returns. If I keep the revs at 1500 as soon as it starts for that 30 seconds there is no fuel smell or rough running at all.

Logs dont tell me much, but look at the spark advance when pressing and releasing the throttle .



Here is log and a video of a typical cold start.

Log:
https://www.dropbox.com/s/n0u55lr5wmsds29/cold_start_overfueling.csv?dl=1
Video: (sorry for bad audio, the blower vent was pointed to the microphone, and can't really re-shoot today)
https://youtu.be/FLPs0B-wbcw

10

Omega Electrical and Audio Help / Re: Wiper stalk

« on: 15 June 2016, 14:52:49 »

By motor test you mean just connecting it straight to power or opening it up? Slow and fast speed have different carbon brushes inside the motor. I had a problem like this and it was a worn slow speed brush (the one that intermittant wipe uses). Try intermittant operation till it acts up, then switch to normal speed and then knock the motor. If it starts spinning: bad slow speed brush.

11

Omega General Help / Re: Rear multiram effect on idle

« on: 15 June 2016, 12:43:47 »

I'm soon off to see what I can find. The reason I'm suspecting an air leak is that idle fuel correction factors are +30% for bank 1, while bank 2 is about 0%. Part load correction for bank 1 is only 2-3%, bank 2 is 1-2%. When revving parked, bank 1 correction goes from 30% towards the 2-3% when throttle is opened more.

What's the theory on the rear multiram not affecting idle? As I understand, it's the only air channel between the two banks. Only thing I can guess is that it's not very air tight closed so idle air can go around it?

12

Omega General Help / Rear multiram effect on idle

« on: 15 June 2016, 03:50:00 »

Hi, I'm tracking down vacuum leaks on my X25XE.

I'm in the process of opening up the plenum soon, but have a quick question for you V6 owners. In theory, on non-DBW engines, actuating the rear multiram (as in closing the valve) on idle should starve cylinder bank 1 of IAC air and thus make the idle very bad. On mine, turning the valve closed does absolutely nothing on idle. This leads me to believe that there is a bad leak on bank 1.

Could someone test their rear multiram and see what happens on idle?
This is to know if I should be extra rigorous on checking bank 1 when I open it up.

Thanks in advance!

13

Omega Electrical and Audio Help / Re: Electrical ground fault and ground locations

« 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?

14

Omega Electrical and Audio Help / Re: Electrical ground fault and ground locations

« 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.

15

Omega Electrical and Audio Help / Re: Electrical ground fault and ground locations

« 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.