Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: bootzey on 22 January 2013, 14:03:25
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Hi All.
Been awhile since I was on. I've still got the same problems...EML on, fuel trim codes but runs fine with MAF disconnected and doesn't go it to limp home. Brought a Chinese MAF off ebay and fitted to car when hot, result EML light off after about 30 miles but still rough starting. Then brought a MAF of Steve at Omega Spares, car exactly the same as my MAF
Here's what's happening:-
Car now won't start with MAF, any MAF, plugged in when cold.
Car starts perfect with MAF unplugged.
Car continues to tick over after plugging the MAF back in immediately after starting, even though it's cold. But when engaging drive, car coughs, splutters, pinks then stalls. Unplug MAF - restarts perfectly.
Plug in the MAF when at driving temperature and car starts and drives until I hit a bump or turn a corner too vigorously. Then runs bad so I have to pull over to unplug....you guessed it..the MAF.
Plug in the MAF when at temperature...ticks over. Then turn off, leave for 2 minutes and attempt restart...and doesn't...plug MAF in and it does.
Got a code reader...yep, a Chinese one and Android Torque. It switches EML off and clears codes but...it's telling me the oil temp is -44!!! But indicates coolant temp the same as the temp gauge. Does anyone think this might be confusing the poor old ECU? Also, where is the oil temperature sender please?
This seems to be a progressive problem. The EML came on along with Check Engine Oil on the MID about 10 miles into the 233 mile journey home from Chester in August. The starting problem has got worse and worse since and now won't start at all, even after 30 odd goes. Can't help thinking that the muppet I brought the car off did something as when I started the car the EML wasn't on but the engine was warm. It's all rather confusing and very expensive on fuel.
Now to confuse things even more I decided to use an amp meter to test the resistance of the 4 MAF's I now own. I haven't got a clue about electrics and the dial switch on the tester totally baffled me. So I just turned it to the ohms section pointing to 20K as it seemed to give a steady logical looking result.
I placed the red lead on the connector for the blue wire and then touched the black wire to the other connectors in turn and made a note of the readings. Then moved the red connector to what I noted as No.2 which is the green wire. Then continued until I had readings for all combinations of connectors. The car's MAF and the one from Steve gave very similar results. The chinese MAF's (yep, I got the ebay seller to send me another) also gave similar reading. However, the readings were completely different to the original Bosch MAF's. Would anyone like me to put the results on here? Can anyone inform us as to what the readings when testing a MAF should be please?
Many thanks if you have read this.
Cheers
Dave
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Measuring the resistance of a MAF won't tell you anything and could damage it.
What you need to do is get it idling, plug the MAF in and have a look at the live data with a code reader. The following parameters would be of interest:
MAF air flow rate in kg/h
Intake air temperature (measured by the MAF)
Fuel trim values
Lambda sensor activity and open / closed loop status.
I suspect a MAF problem has caused the fuel trims to get so high that it's preventing starting but need to see the live data to confirm this.
Also have a look for any stored fault codes in the engine ECU.
In my opinion, non genuine and 2nd hand MAF sensors are a false economy, as they often give problems after very little time.
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Dave, whereabouts in Surrey are you? If I'm passing I'm happy to stop by and sanity check your Chinese code reader with my reader (although mine reports MAF flow in a nutty unit rather than kg/h, sadly)
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Cheers Kev.
I might get the chance later to plug in the code reader.
Is there any way of clearing the stored fuel trims so it has nothing to compare and starts logging again? The last time I had Torque connected it sometimes indicated a fuel trim of 100%! Also showed an intake of 12.5g. The Lambda's were flipping nice and regular between .1 and .8 and were closed loop until it warmed up a bit then they went open.
Could a wiring problem blow a MAF? A dodgy earth or something maybe? Is there a wiring diagram for the MAF indicating which of the 5 wires do what and where they go in existance?
Also, I forgot to mention that after blasting my original MAF with a carb cleaner it worked for a while and the mpg went upto 28 in town! However it didn't last long and hasn't worked again since....that's 20 quid on cleaner wasted lol
What do you reckon on the Oil temp reading?
Thanks again
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Cheers Aaron, I'm just south of Guildford :)
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Not so far from me, then. I'd be happy to look over it with the real McCoy Tech 2. :y
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Yep, not much further really than from my usual route (Bracknell->Chobham->West Byfleet->Chertsey and back) :y
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I bought 95 Mercedes with new Chinese MAF, which didn't work. I bought another cheap MAF, which didn't work either. Finally I bought used MAF sensor from ebay and it worked fine.
I got smarter and when I needed MAF for Catera I got it from junk yard, worked fine!
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Hi Guys
Sorry, not been here for a while thanks to BT, my boys xbox and an unaffordable BT bill.
Thanks for the offers of help but (not wanting to insult you) I wouldn't expect you to do it for nothing, which is all I have at the moment so can't reimberse you.
I just done a bit more testing as there's been some updates from Android Torque. Got some weird scenario's happening :-
Running with MAF unplugged.
3 O2 sensors flipping nicely but bank 2 sensor 2 lags behind and just flips between .1 and .2 volts. Fuel Trim dials show 1x2 and 2x2 unmoving at 92%, Intake temp of -40 degrees C, oil temp -44 degrees C and No injector pulse width reading. Runs closed loop.
Now the confusing bit:-
MAF plugged in....has to be done with car running and up to temp:-
Scenario 1. O2 and fuel trim dials stop working as soon as MAF plugged in, like plugging the MAF in switches them off, fuel trim at 25%. Injector pulse width 71.3ms. Oil temp -22. However...flip the throttle and revs to 1800ish and won't drop until...I turn on the head lights and air con then revs drop!!!!! I cleared the P0100 fault code and the thing runs rough for a while.
Scenario 2. Lights and Air Con off revs to 950, F/T 25%, MAF 3.8gm/second, injector pulse width 71.3ms, oil temp -22
Scenario 3. Lights and Air Con on revs at 750, F/T 16.4, MAF 2.8gm/second, Volume Efficentcy 15.8%, Boost (assume it means vaccum) -12.3%, injector pulse width 71.3ms, oil temp -22.
There seems to be a connection between DB Wire throttle, Plugging the MAF in, turning Air Con and Lights on which will reduce voltage. Can't think why the O2's and Fuel Trim sensors shut down when the MAF gets plugged in unless there's some kind of voltage overload somewhere.
Going to try same scenarios with Omega Spares MAF (ohm performance the same as mine and Steve assures it came of a well running 2.6) and then chinese MAF's (ohm performance the same as each other). I reckon if I get the same thing happening regardless of which MAF is in then it has to be a bad earth or cross wire somewhere.
Phew! Sorry, yet another long post for you to read but I think the devil is in the detail somewhere.
Thanks for reading and understanding.
Dave
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Could be something odd with the wiring but they are also classic MAF sensor issues, and the 2.6 seems very sensitive to a degrading MAF sensor. It would be good to get the MAF sensor reading at hot idle, and see if it varies when pulling the wiring around a bit, but I don't trust the readings from that code reader. Sounds like it's confused by some of the data it's getting. :-\
Bit of a shame I've just passed by the south of Guildford and could have chucked the Tech 2 in the car. ::)
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I had similar problem on my 2.5 getting fault code for Lamda/maf & throttle Pos sensor ran like a pig -it was plug on egr - Got another plug from scrapper and 10 mins soldering-car fine now :y
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By the way, the lambda sensor activity sounds pretty normal. The post cat sensors shoudn't cycle as readily as the pre-cat sensors as the cats damp their response.
Are you getting any fault codes? (do the pedal trick if the code reader isn't reporting any)
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I had similar problem on my 2.5 getting fault code for Lamda/maf & throttle Pos sensor ran like a pig -it was plug on egr - Got another plug from scrapper and 10 mins soldering-car fine now :y
Ops got a 2.6 - no egr on a 2.6 mate ::)
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That's just my luck Kev...don't tell me...you went through Chilworth lol
MAF readings are @ 600 revs 2.8 grammes/second so by me reckoning that's 60secsX60minsX2.8/1000 = 10.08Kg/hour
@ 950 revs 3.8 grammes/second = 13.68Kg/hour
@ 1845 revs 6grammes/second = 21.60Kg/hour
All O2 and F/T readings stop dead when the MAF gets plugged in, DBW throttle doesn't decrease when foots off the pedal but turn lights and Air Con on and revs drop?
Can't understand why the Injector Pulse Width is always the same regardless of revs @ 71.3 milliseconds surely it should change with the revs? And there's no IPW reading unless the MAF is plugged in.
Is there anything behind the dials/dash that would be at risk if a large Latte was split then runs down through the grill by the windscreen then out through the fusebox?
Dunno why but I'm convinced there's a wiring problem.
What replaced the EGR on the 2.6 and 3.2?
Cheers for the in put Guy's
Dave
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Sounds low. But that bluetooth based system often talks 'dangle berries', so slightly reluctant to suggest buying a brand new, genuine GM MAF at this stage.
Don't use 2nd hand or pattern (even if it claims to be Bosch). Dealer only, in GM hologramed box.
Worth fully checking for air leaks as well.
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Not quite Chilworth - I was a bit further South on the A272 but could have made a detour.
I think the code reader has got IPW confused with something else. IPW should be about 3ms at idle when warm.
10kg/h at idle is a little low. 12 or so would be typical. It only needs to be a little low before a 2.6 will start playing up, sadly, and I've seen symptoms of holding revs high before.
The O2 activity stopping indicates that the MAF sensor output has taken the mixture out of the range in which it will operate closed-loop, so I think it reinforces the MAF sensor theory.
I don't think a latte would have caused a problem. ;) Very little of the engine ECU wiring enters the cabin.
Might be worth keeping an eye on the live data when on the move - see if anything goes haywire while turning corners, etc. Assistant in the passenger seat with a laptop?
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Slightly off topic........
The 2.2 cam sensor seems to have a failure mode that randomly screws up communications with other sensors hence giving fault codes for components that are perfectly OK. I assume that means that there is a communication bus (1 ware/i2c/CANbus or similar) that is shared amongst more than one sensor
The 2.6 & 3.2 are a similar vintage so I assume use a similar ECU.
MAF failure on the 2.6/3.2 seems less common than cam sensor failure on the 2.2 but I wonder if the MAF shares a bus with other sensors (hence can screw up other components if faulty) :-\
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Slightly off topic........
The 2.2 cam sensor seems to have a failure mode that randomly screws up communications with other sensors hence giving fault codes for components that are perfectly OK. I assume that means that there is a communication bus (1 ware/i2c/CANbus or similar) that is shared amongst more than one sensor
The 2.6 & 3.2 are a similar vintage so I assume use a similar ECU.
MAF failure on the 2.6/3.2 seems less common than cam sensor failure on the 2.2 but I wonder if the MAF shares a bus with other sensors (hence can screw up other components if faulty) :-\
I think you are confusing sensors knocking out other sensors one a shared bus with the ECU's error handling routines, and other spurious things that happen before ECU can detect which sensor is giving a reading not to be trusted.
All sensors have dedicated wiring back to their associated ECU on the Omega. A quick glance at the schematics will confirm that.
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I should add, thats the very reason not to go purely on fault codes, but look at the underlying live data.
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Slightly off topic........
The 2.2 cam sensor seems to have a failure mode that randomly screws up communications with other sensors hence giving fault codes for components that are perfectly OK. I assume that means that there is a communication bus (1 ware/i2c/CANbus or similar) that is shared amongst more than one sensor
The 2.6 & 3.2 are a similar vintage so I assume use a similar ECU.
MAF failure on the 2.6/3.2 seems less common than cam sensor failure on the 2.2 but I wonder if the MAF shares a bus with other sensors (hence can screw up other components if faulty) :-\
I think you are confusing sensors knocking out other sensors one a shared bus with the ECU's error handling routines, and other spurious things that happen before ECU can detect which sensor is giving a reading not to be trusted.
All sensors have dedicated wiring back to their associated ECU on the Omega. A quick glance at the schematics will confirm that.
I wasn't suggesting that any sensors shared wiring back to the ECU. I agree that the behaviour is probably caused by poorly programmed fault detection but it struck me that the symptoms were rather similar to the problems resulting when one faulty sensor causes intermittent errors on a shared data bus.
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Slightly off topic........
The 2.2 cam sensor seems to have a failure mode that randomly screws up communications with other sensors hence giving fault codes for components that are perfectly OK. I assume that means that there is a communication bus (1 ware/i2c/CANbus or similar) that is shared amongst more than one sensor
The 2.6 & 3.2 are a similar vintage so I assume use a similar ECU.
MAF failure on the 2.6/3.2 seems less common than cam sensor failure on the 2.2 but I wonder if the MAF shares a bus with other sensors (hence can screw up other components if faulty) :-\
I think you are confusing sensors knocking out other sensors one a shared bus with the ECU's error handling routines, and other spurious things that happen before ECU can detect which sensor is giving a reading not to be trusted.
All sensors have dedicated wiring back to their associated ECU on the Omega. A quick glance at the schematics will confirm that.
I wasn't suggesting that any sensors shared wiring back to the ECU. I agree that the behaviour is probably caused by poorly programmed fault detection but it struck me that the symptoms were rather similar to the problems resulting when one faulty sensor causes intermittent errors on a shared data bus.
Sorry, I obviously misinterpreted the highlighted bit :-[
Makes no sense to have dedicated wiring to an ECU, then use an inter ECU shared bus system within that ECU. I've had a Bosch Motronic 2.8.3 apart serveral times, and it strikes me to be a simplistic (at a hardware level) system driven driven by a traditional microcontroller. The 2.6/3.2 Motronic 3.1.1, although I haven't had one apart, I would imagine to be an evolution of this.
As for 2.6/3.2 and 2.2 ECUs being simiilar, they have different heritages, and different evolution. Though both, of course, are little more than a simple fuel/spark mapping system, based on a handful of inputs. 2.2 (and the 2.0 before it) use a Simtec ECU, not the Motronic fitted to the V6.
Hope that makes sense?
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im having exactly the same issues on my 2001 2.6 ended up leaving maf unplugged just for sanitys sake lasted two weeks of perfect running now its dead outsiide my house :-\ one thing to remember never use carb cleaner on a maf fastest way to kill it try taking your live off your battery overnight to force ECU to update to new settings it may help also you were right with earthing points defo check these before you spend any more cash also make sure previous owner havnt tie wrapped wires leading to maf as it could be broken wire inside cable insulation hope this helps just all things iv had to check lol if you come up with a solution can you please let me know as im running out of hair to pull out good luck pal (excuse my typing fat fingers small keys on this phone ) :)
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Slightly off topic........
The 2.2 cam sensor seems to have a failure mode that randomly screws up communications with other sensors hence giving fault codes for components that are perfectly OK. I assume that means that there is a communication bus (1 ware/i2c/CANbus or similar) that is shared amongst more than one sensor
The 2.6 & 3.2 are a similar vintage so I assume use a similar ECU.
MAF failure on the 2.6/3.2 seems less common than cam sensor failure on the 2.2 but I wonder if the MAF shares a bus with other sensors (hence can screw up other components if faulty) :-\
I think you are confusing sensors knocking out other sensors one a shared bus with the ECU's error handling routines, and other spurious things that happen before ECU can detect which sensor is giving a reading not to be trusted.
All sensors have dedicated wiring back to their associated ECU on the Omega. A quick glance at the schematics will confirm that.
I wasn't suggesting that any sensors shared wiring back to the ECU. I agree that the behaviour is probably caused by poorly programmed fault detection but it struck me that the symptoms were rather similar to the problems resulting when one faulty sensor causes intermittent errors on a shared data bus.
Sorry, I obviously misinterpreted the highlighted bit :-[
Makes no sense to have dedicated wiring to an ECU, then use an inter ECU shared bus system within that ECU. I've had a Bosch Motronic 2.8.3 apart serveral times, and it strikes me to be a simplistic (at a hardware level) system driven driven by a traditional microcontroller. The 2.6/3.2 Motronic 3.1.1, although I haven't had one apart, I would imagine to be an evolution of this.
As for 2.6/3.2 and 2.2 ECUs being simiilar, they have different heritages, and different evolution. Though both, of course, are little more than a simple fuel/spark mapping system, based on a handful of inputs. 2.2 (and the 2.0 before it) use a Simtec ECU, not the Motronic fitted to the V6.
Hope that makes sense?
Yes :y
Laziness on my part, I hadn't realised (hadn't bothered to check relevant page on forum :-[) that the ECUs had different heritage.
I still have a sneaky feeling that Simtec cut corners inside their ECU and did something at a hardware level that allows the cam-sensor to interfere with communications to other sensors :-\
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Guys. Thanks for all your input.
Got the car warmed up today and plugged the MAF in and let her tick over...no problems. Then...
went for a quick drive with the scanner connected. Left turn fine, left turn fine, right turn fine, left turn fine, left turn fine then drove a third of a mile through the village...no plod about phew!
Stopped to make a U turn.....not fine. As I turned the steering wheel to the right she lost power and chugged home. As I was doing the U turn I had a quite look at the scanner and F/T was at 25% and the 02's were at 0.00, like they had been switched off!
Got home and let her tick over very roughly then held the revs at 2K, looked at the scanner...same as above.
Released the throttle...revs stayed high.
Turned the lights on...revs dropped abit.
Turned the A/C on revs dropped a bit more.
Turned the steering wheel....revs dropped to normal. Then:-
Released the steering wheel...revs higher.
Turned A/C off....revs higher
Turned lights off...revs abit higher still.
And so it went on for about 10 minutes with any combination or order that I cared to choose.
So, convinced that it had something to with the power steering, I had a look in that general area :
there's about 4 earth wires in a group with a single fixing to the body...look ok but have a grey colouring to them.
Had a bit of a fiddle around and WTF kin hell that hurt...I had burnt the fingerprints of 4 fingers (still in a bit of pain now!!).
I could smell my skin burning...I'm sort of thinking mmm this might be dangerous lol
Had a look under the battery shelf expecting to find something red hot, couldn't see anything that hot.
Tentitively put my hand in to touch something and there's a white bit of electronic kit in a bracket bolted to the body just under the battery, it has a red n blue wire and a red n white wire 1 at each end and was kelly brooke hot.
Had to go to sainsburys so switched the car off, put my fingers under a cold tap for 10 minutes.
Then checked this component just before I left...stone cold, as cold as my poxy fingers lol
Unplugged the MAF and went on my merry way.
Got home and checked this thing again expecting to burn the fingers of my right hand but....stone cold????
The only thing I had done was unplug the MAF.
What on earth is this white electrical thing under the bonnet??
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Chinese MAF turned the EML off immeadiately!!! :D
then when I shut the bonnet...i'd forgotten to put the drivers side windscreen wiper back down....snapped off! >:( oh the joys of owning a car!