Lumpy Idle?

[electricfurnace]

172 Cup - runs very well. Cambelt done under 2 years ago so not due.

Idle becomes lumpy maybe a minute after cold start.

I know they are fairly lumpy but what diagnostic procedure should I follow rather than firing a parts cannon at it? 😁 Its no biggie as it drives superb but wouldnt mind getting it sorted

Cheers

 

[imprezaworks]

Unless it’s really lumpy it should be as it is.

 

[electricfurnace]

Its not cutting out or anything just “surges” a bit on idle. I can’t recall from my old one whether its normal or not!

 

[SharpyClio]

Mine was worse when the timing was one tooth out, but then it would struggle on pick up so if driveability is generally fine then its likely to just be the way it is, i sometimes think mine is about to stall or throw a code when I am at lights but it never does, its a little disconcerting though.

 

[hopgop1]

Have the injectors been done in the last few years? My 182 was the same, a bit lumpier than I'd expected, found 1 bosch injector and 3 originals, replaced all 4 with brand new magneti marelli and was far smoother.

 

[npt]

My cup is exactly the same and always has been, nothing wrong with mine. Think it's just very poor mapping

 

[Robbie Corbett]

Mine did this for a long time and it was the pre cat lambda sensor, eventually it got bad enough to throw an EML.

It only happened after a minute or two of running, I believe the ecu ignores the lambda sensor during warmup hence the delay. Later I had a duff injector which also gradually failed, went from lumpy and rich to full on missfire after a while which again made diagnosis easy.

 

[electricfurnace]

Considered changing injectors but conscious of not throwing the parts cannon at it to be honest! Are OBD diagnostics easily available to pinpont any issues?