M54 2.5 rough idle

[thespannerman]

Guys

About 6 weeks ago has a misfire (very much felt like it was running on 5 not 6 cyls) which seemed to be fixed by fitting 6 new coil packs. I only used the car a couple of short journeys which were ok, then parked it up and went on hols. Skip forward 6 weeks, start the car this morning and it idles really roughly, rocking the whole car. It revs clean (not missing) and seems to pull ok, just not idling well. I have used the search function but there are loads of threads on rough idling. I have had a look around for air leaks (removed air filter box and checked around hoses below) can’t see anything. No error codes on my cheap reader, and no lights on the dash.

Things to look for ?

Cheers
Al

 

[enuff_zed]

Things to look for ?

A better code reader? (Well you did say it was cheap, and the better ones do seem to find more stuff.)
Or someone with Scanner 1.4, INPA, or ISTA.

On a more practical level, check none of your new coils have come loose.

Have you ever taken the Idle Control Valve out and cleaned it?

 

[colb]

In the absence of any codes I would, like enuff_zed suspect a gummed up idle control valve is the cause of your bad idle given that new coil packs have been already fitted. Take the idle control valve out and clean it out with carb cleaner spray, once clean if you shake it in your hand you should here the internals moving about indicating its free and not sticking. Fit it back on ensure all hose connections are tight with no air leaks and start the car, see if you have a normal idle.

 

[thespannerman]

Ok thanks chaps, I’ll get some carb cleaner and give that a go

Is there anybody with Scanner 1.4, INPA, or ISTA. near me ( just off J3 M5)

Cheers

Al

 

[thespannerman]

Ok, got the idle control valve off, and it wasn’t as cruddy as I thought it might be and was “clicking” as you waggled it side to side (which I understand is what I needed to hear), still got some carb cleaner and gave it a good clean so the it was clicking very easily when waggled. Refitted and whilst the idle seems better I wouldn’t say it was smooth, and now I have the “check engine light on” which I didn’t before. My cheap code reader is saying 1 fault code but won’t show what it is.

So a few things….

Other ideas as to what to go looking for next?
Is there anyone close to me with a decent fault code reader (near J3M5)
What fault code reader would be recommended, given it’s my sunny day car so don’t want to throw tons of money at it

And given it’s actually sunny, a bit pissed of that I can’t use it

Cheers
Al

 

[enuff_zed]

What fault code reader would be recommended, given it’s my sunny day car so don’t want to throw tons of money at it

Creator 410+ or Autophix 5900 both seem pretty good.

Or simply buy the Scanner 1.4 gubbins and install on a laptop.
https://www.ebay.co.uk/itm/154021453500

Note that although mine came with the software on a thumb-drive, another member received a CD and didn't have a drive for it. Easily resolved when I sent him the folders via 'wetransfer'.

 

[raymond.harper]

Check the earths on the coil packs, list of people who can help with code reading here. https://z4-forum.com/forum/viewtopic.php?t=144268#p2065849

 

[thespannerman]

Ok thanks, just ordered the scanner gubbins, hopefully here by Wednesday, so see where I go from there

Al

 

[thespannerman]

I guess I ought to have this and my misfire threads joined up.

I got the scanner 1.4 kit, and my issue seemed to be a misfire on cyl4, even after replacing all 6 coil packs. So I moved coil pack 4 to cylinder 1 to see if my problem moved. I cleared the faults, the car was then running and idling smoothly.

Took it out this morning, all was fine, then went out lunchtime and had got intermittent misfire back, but no check engine light on, and after connecting scanner sw, no faults showing.

I am saying misfire as that’s what it feels like, a blip in it pulling cleanly.

Would a spark plug not working correctly show up in the scanner app?

Other ideas?

Cheers
Al

 

[enuff_zed]

Not sure how the DME detects misfires tbh, and if it does detect spark plugs then surely you'd get the same fault when you scanned it.

 

[thespannerman]

That’s what I thought, but no faults showing and there’s a definite hesitation at various points when you try and pull, and it was lumpy when sitting at idle, although the rev counter was dead steady, not like before when the rev counter was all all over the place at idle.

At points on the way back home it would pull cleanly, no hesitant spots, then it would start doing it again. I have had my multimeter on the coil pack earths and these seem to be ok.

I had the scanner connected and ran a scan with it sitting at idle in the garage whilst it felt really lumpy and there were no errors reported.

Bit stumped again now.

Al

 

[enuff_zed]

That’s what I thought, but no faults showing and there’s a definite hesitation at various points when you try and pull, and it was lumpy when sitting at idle, although the rev counter was dead steady, not like before when the rev counter was all all over the place at idle.

At points on the way back home it would pull cleanly, no hesitant spots, then it would start doing it again. I have had my multimeter on the coil pack earths and these seem to be ok.

I had the scanner connected and ran a scan with it sitting at idle in the garage whilst it felt really lumpy and there were no errors reported.

Bit stumped again now.

Al

Can you see any live data for the cam angles? Wonder if a sensor is playing up?

 

[thespannerman]

Not sure how I see live data. I thought doing a scan whilst the engine was running and it was lumpy would show me some faults

For live data do you click on DME whilst the engine is running

Al

 

[enuff_zed]

Not sure how I see live data. I thought doing a scan whilst the engine was running and it was lumpy would show me some faults

For live data do you click on DME whilst the engine is running

Al

I’ll admit I haven’t tried it on the scanner as my Autophix does it.
But in principle yes, click on the DME and see what you can find

 

[thespannerman]

Scanner doesn’t seem to show live data ( but i might be doing something wrong).

Anyway, thrown a new set of plugs in it for good measure, been out twice today, all was good.

I hate intermittent faults, especially those that don’t leave a trace/record.

So will have to keep fingers crossed it’s now all ok

I might be back………………

Al

 

[carl]

What fault code reader would be recommended, given it’s my sunny day car so don’t want to throw tons of money at it

Creator 410+ or Autophix 5900 both seem pretty good.

Or simply buy the Scanner 1.4 gubbins and install on a laptop.
https://www.ebay.co.uk/itm/154021453500

Note that although mine came with the software on a thumb-drive, another member received a CD and didn't have a drive for it. Easily resolved when I sent him the folders via 'wetransfer'.

That would be me. The software actually came on a mini CD which needs to go into a tray loading CD drive. Don't think I've seen one of those for about 20 years. Thankfully enuff_zed came to the rescue.

 

[colb]

Bad plugs just show as a misfire code so it's either the plug or the coil on whatever cylinder the code refers to.

 

[Roger Holdorf]

What about fuel injectors?????