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[megaomega123]

Firstly, sorry it's not an omega. I switched allegiance 4 years ago!
Had misfire on all cylinders about 4 months ago  (z32se)
Suspected cam cover gaskets and was correct. Fixed that and all was good. Still have an oil leak from don't know where.
All of a sudden the car started running rough, eml on and codes said random misfire p0300 and misfire on all 6 cylinders. Also had p0156, lambda sensor. I do have a blow in the exhaust at the front flexi, after all sensors.
Checked cam covers and plug wells, bone dry. I also changed the coil packs when i did gaskets.
I'm at a bit of a loss now, any ideas???

[Marks DTM Calib]

My money would be on the MAF, can you check live values?

The fact your getting a miss fire on all cylinders and the Lambda code is present also points towards the MAF.

[megaomega123]

Can't get live data. Would unplugging the maf make a difference? Reverting it to basic standards?

[megaomega123]

Idles slightly better with maf unplugged but still misfires everywhere!

[Marks DTM Calib]

It will as the learnt values will be a mile out, the fact its improved points you in the right direction, try resetting the codes then running with it unplugged.

Do you know anybody with a 3.2/2.6/2.2dti who you can borrow the maf from to prove?

[Marks DTM Calib]

I am assuming you have checked for air leaks?

[megaomega123]

 Don't know anyone to swap out with. Just in the process of resetting codes and try unplugged maf.
Just taken out air box for a check, all ok. Oil leak looks to be near crankshaft pulley!!!
Checked air leaks and electrical connections as far as possible.

[megaomega123]

No change after reset and with maf unplugged!!

[megaomega123]

Just had inlet manifold off again to check and double check everything. Nothing amiss and still really bad misfire on all 6 cylinders:/

[TheBoy]

Probably does need live data looked at, if you think its not MAF.  Where are you, maybe a local member would be willing to get live data for you

[megaomega123]

I'm near Auchterarder now, will be Ayr in a few weeks.

[megaomega123]

Could the misfire be down to inlet manifold gaskets? They look a little flat. It seems air leak is most probable to misfire all cylinders???

[megaomega123]

I've done the carb cleaner check, which showed nothing. Just done a smoke test and it seems tight as a drum.
I'm leaning back towards the maf now. It does seem to even out when the maf is unplugged.
Is it normal for traction control to switch off when maf unplugged?
Is there any real way to test a maf other than trying another one?

[megaomega123]

Reset ecu and did 5 miles with maf unplugged.
Eml flashed the whole time. Very down on power ( notice that cylinders are missing).
Following codes after run: p0100 maf. P0110 air intake temp. P0300 random misfire.  P0303 misfire cylinder 3
Maf unplugged explains p0100 and p0110.
Should it still misfire with maf unplugged?

[megaomega123]

So, I've just changed the maf, no difference. Then changed both coil packs, no difference!!!
I'm a bit lost as to where to focus now. Really need some help with this 

[megaomega123]

Just been for 30 mile run and still misfiring. It occasionally stops during acceleration and full power is restored. This is only briefly though. Read the codes and have it down to just cylinder 3.
The car is lpg and does the same on both fuels. I unplugged cylinder 3 lpg injector which made no difference. All the others changed engine tone when unplugged in turn.
All plugs were replaced about 4 months ago. Could it be 1 dodgy plug???
Should i just swap over 2 plugs and see if the misfire moves with the plug?

[Doctor Gollum]

Just been for 30 mile run and still misfiring. It occasionally stops during acceleration and full power is restored. This is only briefly though. Read the codes and have it down to just cylinder 3.
The car is lpg and does the same on both fuels. I unplugged cylinder 3 lpg injector which made no difference. All the others changed engine tone when unplugged in turn.
All plugs were replaced about 4 months ago. Could it be 1 dodgy plug???
Should i just swap over 2 plugs and see if the misfire moves with the plug?

Would be prudent for diagnostic purposes

[TheBoy]

Failing that, patch out LPG ECU from injector PoV, in case the LPG ECU has gone up the Gary Glitter.

[megaomega123]

Failing that, patch out LPG ECU from injector PoV, in case the LPG ECU has gone up the Gary Glitter.

Had a bad lpg injector on omega and the misfire didnt replicate on petrol.
I'm not sure how to totally patch out the lpg ecu. I tried unplugging it once but it wouldn't start on petrol!!!!

[TheBoy]

Failing that, patch out LPG ECU from injector PoV, in case the LPG ECU has gone up the Gary Glitter.

Had a bad lpg injector on omega and the misfire didnt replicate on petrol.
I'm not sure how to totally patch out the lpg ecu. I tried unplugging it once but it wouldn't start on petrol!!!!

If the LPG loom or LPG ECU is suspect, due to the way its a piggy back ECU and intercepts the signals to petrol injectors, it can impact running on petrol.

[megaomega123]

Failing that, patch out LPG ECU from injector PoV, in case the LPG ECU has gone up the Gary Glitter.

Had a bad lpg injector on omega and the misfire didnt replicate on petrol.
I'm not sure how to totally patch out the lpg ecu. I tried unplugging it once but it wouldn't start on petrol!!!!

If the LPG loom or LPG ECU is suspect, due to the way its a piggy back ECU and intercepts the signals to petrol injectors, it can impact running on petrol.

So how do I totally eliminate the lpg ecu from the equation?

[TheBoy]

Depends how the fitter intercepted the petrol injectors. Hopefully, on main injector loom plug (in which case, unplug the bits going to LPG), but more likely at the injector itself....

...without lpg, the petrol injector feed plugs straight onto injector. With LPG, that connector is unplugged, and the plugged into LPG loo to take signal back to LPG ECU. There is another wire from LPG ECU that then plugs into petrol injector.  Its a case of unplugging those connectors, and plugging the original injector lead (from petrol ecu) into the petrol injector.

[megaomega123]

I got 1 new spark plug. Took out number 3 and it had no electrodes left and was falling apart. Popped in the new one feeling delighted. Started her up and still the same, if not slightly worse 
Switched 2 injectors but the misfire stayed on cylinder 3.
Now what??

[megaomega123]

Just realised i tested the wrong lpg injector. Just checked three right one and it is dead. Did the spark plug kill the injector or vice versa?

[Stige]

Just realised i tested the wrong lpg injector. Just checked three right one and it is dead. Did the spark plug kill the injector or vice versa?

Bad Injector causing lean conditing burning out the electrode on the spark plug? Just a guess.

[megaomega123]

Think I've finally found the cause. I swapped over the injector plugs and the 'dead one' fired up. The misfire is petrol and lpg so it has to be the wiring from the lpg ecu to the injectors.
Would somebody please concur? It's been driving me nuts.

[Doctor Gollum]

Think I've finally found the cause. I swapped over the injector plugs and the 'dead one' fired up. The misfire is petrol and lpg so it has to be the wiring from the lpg ecu to the injectors.
Would somebody please concur? It's been driving me nuts.

All you've to do now is find the break

[megaomega123]

Even more stumped now!! Checked all the wiring to and from all injectors and nothing amiss. Rewired all the joins to be certain. Still get no signal from the petrol injector on cylinder 3. I followed 'TheBoys' idea of patching out the lpg but still had misfire and no signal on petrol injector 3.
I am really struggling now. If it's a faulty injector then surely the lpg injector would still work?
The lpg ecu reads from petrol injectors then feeds that back to lpg injectors so i presume the fault is between petrol injector and lpg ecu? All the wiring looks intact and good!

[cam.in.head]

are the injectors sequential/ individual on these or do they all fire at once like the old jetronic

[Doctor Gollum]

are the injectors sequential/ individual on these or do they all fire at once like the old jetronic

Same as 2.6/3.2 Omega

[megaomega123]

Yeah sequential. Z32se engine. I've got intake manifold access down to about 4 mins now ha

[TheBoy]

Have you completely removed LPG ecu yet?

What system is it?

[megaomega123]

Have you completely removed LPG ecu yet?

What system is it?

Not completely. Only the injector giving the fault. It is a nevo plus system.
The thing i find strange is that on the software, whilst running, it says no signal on tb4 and tg4. I am assuming that the injectors aren't numbered the same as cylinders.
The lpg injector that isn't getting a signal is numbered 4 but goes into cylinder 3. Although the petrol injector is numbered 3. The software says 4 is the problem for both fuels??

[Doctor Gollum]

Someone has screwed the wiring up then...

[megaomega123]

Someone has screwed the wiring up then...

Well it has been perfect for 4 years so if the wiring was screwed, it would've shown before now!!

[Doctor Gollum]

Someone has screwed the wiring up then...

Well it has been perfect for 4 years so if the wiring was screwed, it would've shown before now!!

What I meant was that the LPG injectors should correspond with the petrol ones... That they don't muddies the water, but could suggest an issue with the LPG ecu or loom

[Marks DTM Calib]

are the injectors sequential/ individual on these or do they all fire at once like the old jetronic

Sequential (most setups have been since the Motronic introduction, Gm went pretty much al sequential since the C20XE days)

[Kevin Wood]

Someone has screwed the wiring up then...

Well it has been perfect for 4 years so if the wiring was screwed, it would've shown before now!!

What I meant was that the LPG injectors should correspond with the petrol ones... That they don't muddies the water, but could suggest an issue with the LPG ecu or loom

That depends on the wiring loom you get with the ECU. Often the grouping of the wires means that you can't follow the cylinder numbers accurately. It doesn't matter to the LPG ECU as all the injector channels are identical.

[cam.in.head]

are the injectors sequential/ individual on these or do they all fire at once like the old jetronic

Sequential (most setups have been since the Motronic introduction, Gm went pretty much al sequential since the C20XE days)

thankyou. apart from my omegas everything else i have is still jetronic !

[megaomega123]

Someone has screwed the wiring up then...

Well it has been perfect for 4 years so if the wiring was screwed, it would've shown before now!!

What I meant was that the LPG injectors should correspond with the petrol ones... That they don't muddies the water, but could suggest an issue with the LPG ecu or loom

That depends on the wiring loom you get with the ECU. Often the grouping of the wires means that you can't follow the cylinder numbers accurately. It doesn't matter to the LPG ECU as all the injector channels are identical.

Yay, I've been waiting for the expert!! So by that reasoning, when the software reads 0.0 for tb4 and tg4 does that mean that the lpg refers to the petrol injectors by the lpg injector number? Because lpg injector 4 sits on cylinder 3 and there was a number 3 tag on the petrol injector that supplies cylinder 3.
When following the wires the lpg injector for cylinder 3 is not wired to the petrol injector for cylinder 3.
Yet it says tb4 / tg4 not working.  I am so confused!!!!

[megaomega123]

I think the penny might have just dropped! The little number tag on the lpg injectors must refer to it's corresponding petrol injector number. Because i run 99% on lpg that explains the misfire on cylinder 3 but the lpg software saying the issue is with 4. also whilst testing over the past few days 'on petrol' p0304 came up.
So the issue seems to lie with petrol injector 4 not giving a signal to the lpg ecu?
So what is the likely cause? Wiring, ecu or petrol injector?