N52 Stuttering Under Acceleration (only when warm?)

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ph1l1p

Member
 Chichester, West Sussex
Hi everyone,

I have recently picked up an e89 30i and I am really enjoying it, but I am having one quite frustrating issue.

When accelerating, there is a bad stuttering, sometimes just one or two stutters, sometimes it sounds like a machine gun for a few seconds. I noticed earlier that the issue doesn't seem present when the engine is cool but happens consistently when up to temp. This seems to happen at any RPM. When it isn't stuttering, it seems to pull well throughout the rev range.

I have scanned and there are no codes on any modules that could relate to the issue.
The spark plugs, coil packs, disa valves, vanos solenoids and MAF have all been replaced relatively recently, all by the previous owner.
The engine idles nicely, but sometimes when it has just been cold started it isn't as smooth as I might have thought for a few seconds.

Does anyone have any suggestions on what to try or what it could be?

Thanks.
 
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Well, I do have sth. slmiliar on my E61 N52. Sometimes I can read ignition drops as fault codes, sometimes catalysator convert faults. Very random, more on a warm engine.

As I've replaced all the components you mentioned as well, I tend to an issue on the DME.

I found hints and even a YT video describing the ignition related transistors inside of the DME.
 
"The spark plugs, coil packs, disa valves, vanos solenoids and MAF have all been replaced relatively recently, all by the previous owner".
Sounds as though previous owner had problems.
 
I've had a similiar issue and it turned out to be the eccentric valve sensor. Don't know for sure if it was the actual sensor or the oil saturated connector.
 

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javis20 said:
I've had a similiar issue and it turned out to be the eccentric valve sensor. Don't know for sure if it was the actual sensor or the oil saturated connector.
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Yeah, it seems like this is the problem, as well as some tatty coil packs. I wiped up a bit of oil residue that was inside the connector and it started running properly. It's a shame it wasn't replaced when the rocker cover was replaced a little while ago.
Thanks.
 
flybobbie said:
"The spark plugs, coil packs, disa valves, vanos solenoids and MAF have all been replaced relatively recently, all by the previous owner".
Sounds as though previous owner had problems.
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Maybe. I know what it is now anyway - ESS seems to be leaking into the connector very slightly.
Also, the car is on about 120k, so it's entirely possible this stuff was just replaced to give the engine a bit of a refresh. If it hadn't been done already i might be inclined, even if it was running fine.
 
Keep an eye on it. In my case the oil was coming up thru the connector, not leaking into the connector externally. Broken internal seal. Repair requires pulling the valve cover.
 
flybobbie said:
Clean the plug with electrical contact spray, good quality one.
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Exactly what i did :)
Seems fine for the moment, but I don't expect the issue to be gone for good - it will probably come back in a couple of weeks.
javis20 said:
Keep an eye on it. In my case the oil was coming up thru the connector, not leaking into the connector externally. Broken internal seal. Repair requires pulling the valve cover.
Click to expand...
Yeah, I will probably replace the sensor in the summer. I just want to see how long it takes before it comes back - if it is super slow to return I will put it off and keep it clean. If it comes back quickly I'll get on top of it quickly.
 
What kind of coil packs did the previous owner fit? They could be some dodgy ones... better fit Delphi, which is the OEM part.
 
Varixto said:
What kind of coil packs did the previous owner fit? They could be some dodgy ones... better fit Delphi, which is the OEM part.
Click to expand...
It was an odd mix of NGK and Bosch. Should be good quality but not good condition. One had a crack on the top clip and they looked dirty inside even though there was no sign of anything on the spark plugs or in the space around them. I suspect he may have swapped them from his new car as he had not long replaced the ones in this car.
A nuisance, but i will get some Delphi's soon. Currently got some Bosch ones swapped in from my M54 e85. They're a bit old but they work a far better so they'll do until I order the new packs.
 
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