[craiger666]

I have a 2014 BMW 220i (F22) - it recently threw up a drivetrain malfunction which I presumed was due to driving with low fuel as it went away when I filled up. A few days later it was back again and it hasn't gone away since.

The scanner showed it as misfiring in 3 of the 4 cylinders so I have replaced the coil packs, spark plugs and most recently the fuel injectors but its still showing a misfire in 1 of the 4 cylinders and the drivetrain malfunction reduced power keeps showing up.

Car is idling very hard and shakes heavily when under 2000 revs or under acceleration.

Anyone seen this problem before - any help or advice is much appreciated.

[flybywire]

My 2015 235 had similar symptoms. I replaced the spark plugs and coils myself. After changing them I had a terrible idle and poor power, and still had a code. I swapped the old coil back onto the cylinder with the code and it ran perfectly. Swapped the new coil back on and it still ran perfectly!
So one possibility is that one of your new coils is not seated all the way. Pull them off and reseat and see if that helps.

BTW, I hope the spark plug job is easier on the 4-cylinder! On the 6-cylinder you have to remove the strut brace and a whole bunch of plastic thingies to reach the two rearmost cylinders.

[atek]

misfire on 1 of 4 after changing those parts...I would revist to make sure everything is installed correctly. Are the coil packs fully seated? Coil pack wiring harness fully connected? All spark plugs tightened down properly? Are the spark plugs properly gapped?

Does the code determine which of the 4 is misfiring? cyl1/2/3/4? or random misfire?

If its random misfire, that could be a few things that need more diagnostic.

If its localized on one particular cylinder, then it gives you a place to start and the parts you have already changed to look into again.

[JMcLellan]

How is the health of your fuel pump? That is one additional that might be worth looking at to see if that is the issue.

[craiger666]

I'll definitely try pull out the plugs and stick them back in and see if that resolves the issue! It's easier on the 4 cylinder thankfully, you can get to them handy enough!

It's only showing in cylinder 2 now where as it was 1,2 & 4 previously so it looks like its solved most of the problem so hopefully they are just not seated properly.

I was looking online and saw the fuel pump could potentially be faulty but I would have thought the diagnostic would throw up a code for that specifically?

[atek]

Originally Posted by craiger666

I'll definitely try pull out the plugs and stick them back in and see if that resolves the issue! It's easier on the 4 cylinder thankfully, you can get to them handy enough!

It's only showing in cylinder 2 now where as it was 1,2 & 4 previously so it looks like its solved most of the problem so hopefully they are just not seated properly.

I was looking online and saw the fuel pump could potentially be faulty but I would have thought the diagnostic would throw up a code for that specifically?

Check cyl 2.

Fuel pump issues usually point to Random misfire as opposed to a misfire on a direct cylinder, especially since you already replaced injectors. Double check your work.

[craiger666]

Appreciate the advise - it was done by a mechanic so would have thought that wouldn't be the issue but I guess everyone makes mistakes.

Mechanic said it might be a timing issue? Thoughts on this?

[atek]

Originally Posted by craiger666

Appreciate the advise - it was done by a mechanic so would have thought that wouldn't be the issue but I guess everyone makes mistakes.

Mechanic said it might be a timing issue? Thoughts on this?

timing related is highly doubtful, though how many miles are on the car? And yes, everyone is human and make mistakes-even seasoned mechanics (like myself)

[craiger666]

Originally Posted by atek

timing related is highly doubtful, though how many miles are on the car? And yes, everyone is human and make mistakes-even seasoned mechanics (like myself)

It's 112k kms so 69k miles. Have to go back to get them to check if plugs or coils are faulty but if he's recommending something that doesn't make sense I'm hesitant. Already spent 800 in parts and labor to get to this point 😅

[atek]

Originally Posted by craiger666

It's 112k kms so 69k miles. Have to go back to get them to check if plugs or coils are faulty but if he's recommending something that doesn't make sense I'm hesitant. Already spent 800 in parts and labor to get to this point ��

At that mileage timing should be fine. Usually with timing component issues, there is some audible noise accompanying the bad or sporadic idle/driving behaviors caused by off or walking-off timing.

A single misfire on 1 cylinder rarely points to timing. Usually an issue with the ignition/fuel related parts of that cylinder. Could be a simple faulty coil pack.

A simple test, swap coil packs with a known good one from another cylinder.

If the misfire follows the coilpack you swapped, then you have found your issue.

If it still remains on the same cylinder even after switching coil packs, it points to either spark or fuel of that cylinder. Hope this helps

[craiger666]

Originally Posted by atek

At that mileage timing should be fine. Usually with timing component issues, there is some audible noise accompanying the bad or sporadic idle/driving behaviors caused by off or walking-off timing.

A single misfire on 1 cylinder rarely points to timing. Usually an issue with the ignition/fuel related parts of that cylinder. Could be a simple faulty coil pack.

A simple test, swap coil packs with a known good one from another cylinder.

If the misfire follows the coilpack you swapped, then you have found your issue.

If it still remains on the same cylinder even after switching coil packs, it points to either spark or fuel of that cylinder. Hope this helps

Amazing, appreciate the help. Will update and let you know the outcome. Fingers crossed its simple fix 🤞

[atek]

Originally Posted by craiger666

Amazing, appreciate the help. Will update and let you know the outcome. Fingers crossed its simple fix 🤞

No problem. Glad to be of assistance! Do let us know what you find.

[dmaxdmax]

Before accepting a possible 'story' about it being something else, maybe ask politely if he'll try swapping coils around to see if the code follows, or something like that?

It's not infrequent a mechanic will find another part that was complicit in your issue, but here, clear code for a cylinder, does, as mentioned, limit issues to right there. I'm surprised you have any coil issue at all...or injector. (I bet it was just a slip in assembly...hope so)

[craiger666]

Unfortunately that didn't solve the problem. There's a lot of pressure in the engine when removing the cap which led mechanic to believe there might be a warped head gasket...Over €2k to fix...

[aerobod]

A failed oil separator / crankcase ventilation system could also cause pressure build up. Before concluding a head gasket failure, a compression test and test strips to check the coolant for combustion gases are also worthwhile.

[atek]

Originally Posted by craiger666

Unfortunately that didn't solve the problem. There's a lot of pressure in the engine when removing the cap which led mechanic to believe there might be a warped head gasket...Over €2k to fix...

Originally Posted by aerobod

A failed oil separator / crankcase ventilation system could also cause pressure build up. Before concluding a head gasket failure, a compression test and test strips to check the coolant for combustion gases are also worthwhile.

I agree with aerobod, a compression and leakdown test should be performed next before any other assumptions or parts replaced-that's the best way to know if the internals are good or not at this point.

[craiger666]

Originally Posted by atek

I agree with aerobod, a compression and leakdown test should be performed next before any other assumptions or parts replaced-that's the best way to know if the internals are good or not at this point.

Yeah - have it booked in for a full diagnostic and these tests with BMW next week. Hopefully get to the bottom of it.