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Platinum BFuk Member
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Discussion Starter · #1 · (Edited)
Hi,

I've had a long running issue with engine stalling, engine management light and error codes.

The mobile mechanic I use fixed the misfire issue by changing (showing my ignorance here) one of the pre-cat lambda sensors (so in the engine bay) and one of the post-cat lambda sensors (so checking the exhaust fumes post-cat?). Ultimately the pre-cat sensor didn't help, but worked once changed for a BMW supplied one.

I was still getting occasional rough running and/or the engine revs jumping up and down when stationary (only for a few seconds to minutes at a time) so the other post-cat sensor was changed. Apparently that's in a closed loop with the other sensor? As soon as either of things (rough running / revs bouncing about) started, the engine management light would come on.

The fourth sensor had been changed less than a year ago.

Anyhow, I just checked the codes and I have the following. The mechanic, by text, has said it's either the spark plugs or coil packs. The plugs aren't that old (3 years old maybe but mileage has been quite low) and I expect they could be checked visually? As for the coil packs....well I've seen adverts for all six at £299......that plus fitting is pricey!

At the other end of the scale I've seen these, would welcome recommendations for decent but not overly pricey sets: Amazon coil packs

Any ideas from the codes? Btw, the engine management light is on all the time. The car drives fine with just 30-60 seconds of grumpiness every 100 - 300 miles.....

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Thanks,
Andy
 

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Almost certainly not coil packs or spark plugs.

your code reader doesn’t say if the fuel trims horn rich or lean. Have a look at the fuel trims on live data and you’ll know.

Have a look at the short term fuel trim on live data, and see when it’s + or - excessively, that will help you diagnose the actual problem.

As others have said, check for air leaks, smoke testing is the best way.

Lean could also because by fuel pump issues, blocked fuel filter, pressure reg issues.
 

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Platinum BFuk Member
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554 Posts
Discussion Starter · #7 ·
Almost certainly not coil packs or spark plugs.

your code reader doesn’t say if the fuel trims horn rich or lean. Have a look at the fuel trims on live data and you’ll know.

Have a look at the short term fuel trim on live data, and see when it’s + or - excessively, that will help you diagnose the actual problem.

As others have said, check for air leaks, smoke testing is the best way.

Lean could also because by fuel pump issues, blocked fuel filter, pressure reg issues.
Thanks - Sod’s Law is that engine management light just went out! I hadn’t cleared the codes.

Regarding the other posts - I definitely needed to change the pre cat sensor - it was stalling when hot before that, but not since the change.

Not sure where to find a reasonably priced specialist near me - Stroud, Glos.

Dealers and indie specialist are crazy expensive.

Any recommended tutorials / YouTube vids for the smoke test? Would air leaks account for the intermittent nature of the fault?

Thanks
Andy
 

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Platinum BFuk Member
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554 Posts
Discussion Starter · #13 ·
Almost certainly not coil packs or spark plugs.

your code reader doesn’t say if the fuel trims horn rich or lean. Have a look at the fuel trims on live data and you’ll know.

Have a look at the short term fuel trim on live data, and see when it’s + or - excessively, that will help you diagnose the actual problem.

As others have said, check for air leaks, smoke testing is the best way.

Lean could also because by fuel pump issues, blocked fuel filter, pressure reg issues.
Hi,

is that under oxygen-sensor control/mixture? I’m not really sure what I’m looking for.

Also car started idling roughly, management light back on - cleared codes with engine running and it’s smooth again - why would that be?
 
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