Running on 5 cylinders

[nosenuggetz]

Hi all, (First post - new owner)
 
I've got a 2010 E89 Z4 35is with M Sport pack and ESS Stage 2 Tune
 
Recently purchased with 89000km on the odometer.  Collected and drove 2600km home over a week - all highway driving.  
 
The car had been laid up for nearly 2 years by prior owner and I was expecting a few issues.  But to my surprise the car was awesome apart from a slight shudder at low revs taking off.  But after about 1000km into the trip it disappeared.  It felt like clutch judder but now I’m wondering if it was a kind of misfire at low rpm.  Happily I got the car home all the way from the top to the bottom of Australia.
 
Weeks later, after getting it registered, I took it out for a short blast around to celebrate.  I pushed it hard on the highway briefly with a few spirited acceleration and brake tests - It spontaneously developed a consistent misfire. It was evident I was running on 5 cyl only.
 
Scan tool showed error code ‘29CD Combustion misfire, Cyl 1’
I swapped ignition pack on cyl 1 with cyl 2.
Fault moved to cyl2 but cyl1 was still problematic.
After the move I got ‘30A1 Ignition Coil, cyl 2 activation’
 
I concluded plug 1 was fouled due to ignition issues and the coil pack on cyll 1 must have then fully failed due to increased load applied to it by the engine management.
 
I swapped coils back (cyl 2-to-1) and cleared errors and sure enough the error came back as misfire on cyl1 again and cyl2 was OK again.  Giving 30A0 Ignition Coil, cylinder 1 activation and 29CD Combustion misfire cyl 1.
 
I replaced all plugs and ignition coil packs with new Bosch replacements.
 
The car fired up first go, but I noticed an occasional single miss every 10-30 seconds but overall it was  generally running fine and smooth on all cylinders.  The miss felt like an ignition miss as it was a mere fraction of a second - like one single cylinder in a cycle.
 
I drove 5-6km - no problems at all.
 
Then on a slight slope I floored it and it stuttered.  I slowed and tried again, and sure enough another misfire had developed and it was back to running horribly on 5 cyl.

Scan test now shows ‘2E18 Firing, Cyl 1’ and ‘29CD Combustion misfire, Cyl 1’
 
The 2E18 error is new.  It means 'DME: Firing, cylinder 1' and the fault code indicates a "activation" failure of the ignition coil on cylinder 1.  This is very specific isn't it!  Makes me think there's a wiring problem but it only shows up under heavy load on a full throttle run.
 
I’ve got a spare Mark 12 injector on order and plan to swap out the injector in cyl 1.
 
I fear that the DEM (engine module) has a failing driver in it.
 
I know there are plenty of misfire threads already but I feel like this one is quite specific and subtle and I'm not sure how it could be the injector based on errors referring to ignition failures.
 
The valve cover and gasket was replaced before I picked up the car.  I suppose it's possible someone messed up a fuel line or there's a crack in the valve cover that could cause an issue but I haven't seen any issues like this yet.
 
Does anyone else have any suggestions?
 
P.S> The car is on Index 8 injectors on all cylinders.

 

[raymond.harper]

The injector is the next thing to look at but check the earth wiring on the coil packs.

 

[flybobbie]

If you just the bought car, start a fresh, replace all coils and plugs.

 

[nosenuggetz]

I let it sit in my garage overnight. Cleared error codes. Pulled cyl 1 coil, checked the plug, plug was clean and not sooty, sprayed some wd40 on the coil terminals and put it back together.

It fired up first go and did not show any errors. Idled smoothly with no misfires.

So, if the injector were to blame for the errors it is simply not firing fuel rather than over fueling. Not sure which is more likely.

If it’s the mosfet driver on 1 in the DEM then it’s only showing up as a full fail when hot and under full load.

 

[nosenuggetz]

Thanks for your reply. I’ve already put new plugs and coils on all cylinders.

 

[B21]

It’s a diagnosis by exclusion..the N54 ECU is not that smart to work out most injection failure modes…

I’d swap out injector 1..of course officially you should have all index 12 in all of bank 1 ie 1,2,3

I’d put index 12 in cyl 1 and see what gives…the fuelling has to be coded..

If the problem continues then maybe it’s a mosfet

 

[nosenuggetz]

It’s a diagnosis by exclusion..the N54 ECU is not that smart to work out most injection failure modes…

I’d swap out injector 1..of course officially you should have all index 12 in all of bank 1 ie 1,2,3

I’d put index 12 in cyl 1 and see what gives…the fuelling has to be coded..

If the problem continues then maybe it’s a mosfet

Yep, that’s what I’m thinking. Index 12 injector is on the way in the mail… I’m reluctant to swap cyl1 injector with any other at the moment as I don’t have a supply of the seals at home. I have the right coding gear to configure the injector.

I’m wondering what’s more likely to give failure under heavy load. Each time it’s developed the misfire (on old plugs/coils and on new plugs/coils) it’s been just after a full throttle short blast. Presumably this is putting additional demand on the fueling and not enough fuel is coming out of injector 1. The plug in cyl 1 is too clean directly after the failure for it to be a rich condition misfire. So, that suggests lack of fuel to cyl 1.

Does anyone know if failing injectors are more likely to leak excess fuel than to produce less than required?

 

[B21]

It’s a diagnosis by exclusion..the N54 ECU is not that smart to work out most injection failure modes…

I’d swap out injector 1..of course officially you should have all index 12 in all of bank 1 ie 1,2,3

I’d put index 12 in cyl 1 and see what gives…the fuelling has to be coded..

If the problem continues then maybe it’s a mosfet

Yep, that’s what I’m thinking. Index 12 injector is on the way in the mail… I’m reluctant to swap cyl1 injector with any other at the moment as I don’t have a supply of the seals at home. I have the right coding gear to configure the injector.

I’m wondering what’s more likely to give failure under heavy load. Each time it’s developed the misfire (on old plugs/coils and on new plugs/coils) it’s been just after a full throttle short blast. Presumably this is putting additional demand on the fueling and not enough fuel is coming out of injector 1. The plug in cyl 1 is too clean directly after the failure for it to be a rich condition misfire. So, that suggests lack of fuel to cyl 1.

Does anyone know if failing injectors are more likely to leak excess fuel than to produce less than required?

Failure modes are many and various on the injectors..carbon builds up and limits the volume/alters spray pattern..injectors leak under pressure, injectors just fail..your engines behaviour suggests a clogged injector..until its check by a service entity who knows..especially witha relatively 'soft' fault..

 

[nosenuggetz]

Thanks again for replying.

Given that the car started up fine again last night after merely pulling the plug and coil and refitting, I think I can rule out clogged injector.

So it seems like electrical failure in the injector itself or the mosfet driver in the DEM on cyl 1.

Earth on wiring appears solid but I’ll pull it and double check and apply some electrical jointing compound just to be sure.

If only I could get a spare injector quickly. Waiting waiting waiting.

 

[nosenuggetz]

Righto. I replaced 1 fuel injector with a second hand index 12. I’ve done about 200km driving and all 6 cylinders are still firing.

There’s still a small miss now and then at idle. I suspect one of the other injectors isn’t playing nice.

Thanks for advice and help guys.

 

[B21]

Righto. I replaced 1 fuel injector with a second hand index 12. I’ve done about 200km driving and all 6 cylinders are still firing.

There’s still a small miss now and then at idle. I suspect one of the other injectors isn’t playing nice.

Thanks for advice and help guys.

Once one injector goes usually the others aren’t far behind..