N46 Coil Pack Lifting

[DarrylvanNiekerk]

Looking for some advice.

I have been battling with rough running and intermittent misfires on an e90 320i - N46.

After a lot of back and forth I have eventually identified it as the front coil pack lifting off of the spark plug and not making good contact.
The sparks are 22000km old as are the coil packs - NGK and Dekra respectively.

I have left the top engine cover off so I have constant access to the coil pack in order to confirm it is making good contact - see hovering I have to do before every trip now.

I can't figure out how to secure the coil pack so it can't lift, I think as the car heats and cools the coil lifts and sometimes there is a very noticeable gap when I press it back down.

I have tried cleaning the spark plug porcelain, cleaned the coil pack rubber, taped the coil pack rubber with fabric electrical tape and also tried to compress the rubber with heat shrink and nothing has worked.

I've tried searching for a solution online but the closest suggestion was finding a way to secure the pack in place but can't see anything I can use as an anchor point.

Any suggestions would be greatly appreciated.

 

[Spanky]

I would just replace honestly, not an expensive exercise.

 

[DarrylvanNiekerk]

I would just replace honestly, not an expensive exercise.

Sorry I got the brand wrong, they are Delphi coil packs.

What would potential issues be with mixing brands, like throwing a Bosch one in to replace the errant Delphi one?

Considering the spark has been messed around with this should I replace them at the same time

 

[Spanky]

Putting a Bosch in that location, while the others remain Delphi, is not going to be an issue if they're built to the same specification.

To determine where your interfacing issue lies, plug side or coil side, you could replace only the cheapest item of the two first and see whether you have resolved things. If not, replace the other too. You could also swap a pair of packs around and see whether the misfire moves with, then you know it's the pack and not the plug.

Personally, I like to replace those types of consumable components in batches (i.e. all coil packs together and all spark plugs together).
That said, it's not absolutely necessary, but it does give one a new datum and known-good reference point which is better practice IMO.

 

[DarrylvanNiekerk]

Putting a Bosch in that location, while the others remain Delphi, is not going to be an issue if they're built to the same specification.

To determine where your interfacing issue lies, plug side or coil side, you could replace only the cheapest item of the two first and see whether you have resolved things. If not, replace the other too. You could also swap a pair of packs around and see whether the misfire moves with, then you know it's the pack and not the plug.

Personally, I like to replace those types of consumable components in batches (i.e. all coil packs together and all spark plugs together).
That said, it's not absolutely necessary, but it does give one a new datum and known-good reference point which is better practice IMO.

Thank you very much.

I know it is the front coil pack because this is the only one that can be pushed back down and afterwards the idle is clean again.

As you say it's best to replace in sets but it is not the performance of the coil pack just the fact that it is lifting which I can't understand why.

If I may pick your brain quickly please:

Delphi coils bought from BMW on special cost R2600. Would Bosch be a better choice and where do you normally buy from?

I actually think I have Bosch plugs in.
I see you can get Platinum ones for not much more then standard copper ones, I can't see the Iridium being worth the extra cost.
What would be the best set of plugs to use on this car?
Full rebuild, slightly higher compression than normal, using 5W30, engine has around 25000km on it, aftermarket decat exhaust.

 

[Greenz]

Diesel electric stock bosch.

I'd probably swop the coilpack in question with another one just to be 100% sure it is indeed the problem.

 

[Spanky]

I know it is the front coil pack because this is the only one that can be pushed back down and afterwards the idle is clean again.

Okay, but does that specific coil pop up on other plug locations too? If so, you know its the coil itself. If not tested at other locations, you still don't know for sure which side of the interface (plug or coil) is the issue.

I'd say figure that out first before worrying about replacing both sets of components (which wasn't implied, and is overkill).

 

[DarrylvanNiekerk]

Okay, but does that specific coil pop up on other plug locations too? If so, you know its the coil itself. If not tested at other locations, you still don't know for sure which side of the interface (plug or coil) is the issue.

I'd say figure that out first before worrying about replacing both sets of components (which wasn't implied, and is overkill).

Thank you very much for the sane advice, I think the frustration of living with and chasing down long term faults can cause one to make irrational decisions.

 

[DarrylvanNiekerk]

@Spanky - another off beat query if I may.

I have been battling with a low rev flat spot when slowing down for say a speed bump and then accelerating in second or third.

I sent the car to a tuner to confirm all was well after rebuilding the engine. I am not a mechanic and learned everything online, this was a full top and bottom rebuild.

The tuner found a faulty MAF and was getting a fault from inlet side leading to a suspected fault from VANOS adjustment actuator.

I replaced MAF and tested the AFRs and get near perfect results leading me to believe all sensors are working correctly.

I get the feeling the inlet adjuster may be worn or sticking and oil pressure needs to build enough to overcome this before the valve adjustment is sufficient for decent acceleration. I did strip the oil pump when rebuilding and did not find signs of major wear or anything passing through the pump causing damage.

VANOS solenoids were cleaned, move easily and click nicely when power is applied.

Does this thinking make sense or do you have any other supposition?

 

[Spanky]

No suggestions there, bru.

Seems like the car has had extensive work. I'd stick to the providers involved, as they have the best context available for troubleshooting, being the ones who have walked the path with you so far.

 

[DarrylvanNiekerk]

No suggestions there, bru.

Seems like the car has had extensive work. I'd stick to the providers involved, as they have the best context available for troubleshooting, being the ones who have walked the path with you so far.

I was the only provider involved...

The only things I outsourced was machining and head rebuild, everything else I did myself.

I made sure to replace everything I could think of or read up was necessary.

Funny thing is the flat spot at low RPM in second or higher gears was there before the engine died and got rebuilt.

Thank you for your help.

 

[Spanky]

Ah, I see.

And the tuner? Surely a thorough tuner will be able to identify where the deficiency lies - be it valve train, fueling system, ignition system or what have you.

 

[DarrylvanNiekerk]

So this is where things start to get a bit tricky.

In the slow run down to its ultimate death the mechanic I was using at the time tried to resolve the hesitation. Tested fuel pump, fuel pressure, changed a number of parts and even had the ECU tested.

I know someone messed with the ECU because the 6500rpm limit was removed.
I'm not sure what else was fiddled with.
This was before I understood the vehicle and had the ability to do repairs on my own so was merely going by words and suggestions that sounded like a foreign language to me.

In the rebuild phase I had the injectors cleaned and tested.

When I sent the car to the tuner he said the ECU appeared to be locked and he could not get in to check parameters.
He noted fault codes from the MAF and inlet settings which he suspected pointed to the VANOS adjustment unit.

We replaced the MAF and the car ran better but it was down on KW even accounting for the altitude power loss in JHB.

His suggestion was to sort the VANOS and then revisit the exercise because it was pointless trying to flash the ECU or spend time trying to crack it if the engine itself has what appears to be an inherent fault with a part.

The rough idle was also present at the time and I have been trying to lock that down ever since which leaves me where I am right now with the coil / spark issue.

It is all a bit frustrating because I know I need to find and solve one or two small issues before the puzzle falls into place.

 

[Spanky]

Seems you've done a fair bit of troubleshooting already then. Fuel pump and injector checks stand out.

All I can say is that you'll need to be methodical, and through a process of elimination, try identify the cause(s).
I'm not sure whether your description above is exhaustive, but you could still look at things like:

State of air filter
State of all plugs - maybe you have some significant fouling or gap issues
State of all coils - maybe you have a deeper issue than just the singular coil which pops up sporadically
Verify no vacuum leaks
Lambda sensor integrity (although the tuner would've flagged this already in all likelihood)
TPS integrity
Fuel filter