Cold Idle Issues

[g8jka]

I have been having some idle issues but only when cold, it goes completely once the car is warmed up.

The longer it idles the worse it gets, almost to the point of stalling. The only code I'm getting is a Lambda one which can't be causing it. It started not long after rebuilding the DISA which I though may be causing it, but swapped with a known working unit and it still does it. I've cleaned the idle control valve, intake hoses are not split, swapped the MAF for a known working one, spark plugs look OK. I did a rough idle test through INPA but this was once it was warm and cylinder 1 was giving a funny reading, but I don't understand any of this?

But, I've cleared the adaptations in INPA a few times now and every time it's cured the problem completely. Eventually it does come back. Any ideas what I should be looking for next?

 

[Mor61e]

That is exactly what a dodgy lambda sensor would cause isn't it? Iffy 02 readings causing the car to adjust fuelling to suit, hence the funny idle

Why do you count it out?

 

[colb]

If the lambda set a code then something is obviously wrong with it, best replace it but clear the code first and see if it returns before lashing out on a new one, get an OEM make Bosch or Seimens brands.

 

[gookah]

not necessarily
The lambda will set a code if its at fault, but can also set a code if it falls outside of its limits from a fault elsewhere upstream like a vacuum leaks. I would spray engine start around the manifold where the vacuum plugs are at the bulkhead end and also the ccv hoses to see if there are any leaks from any of them
The revs will rise if there is a leak

Also change coil pack and plug from 1 to 6 to see if the rough running swaps cylinders.
then change them if it does

 

[colb]

Good call from gookah re code set because something is wrong upstream of the lambda, could be an air leak but seeing the rough running on cylinder 1 it could well be a duff coil pack on No1, unburnt fuel being picked up by the lambda and setting the code. Try moving coil no 1 to no 6 as he suggests and see if the rough running moves to no6. If it registers the same on No6 change the coil.

 

[g8jka]

That is exactly what a dodgy lambda sensor would cause isn't it? Iffy 02 readings causing the car to adjust fuelling to suit, hence the funny idle

Why do you count it out?

Not ruled out the lambda, but it's intermittent as it comes on a goes off quite often. I can cleared the lambda code and not have it back on for days, but the rough idle is still there even with the lambda code cleared.

When the adaptations are cleared the problem goes completely which has to be another reason it probably isn't an air leak as surely clearing the adaptations would not cure an air leak?

Engine light came on again this afternoon, presumably the lambda, not scanned it yet. If my cold idle issue pops up again in the morning now the engine light has come on then it's pretty certain this is causing part or all of the problem.

I need to change the coil pack around and see what happens, something isn't right there. Luckily the car still drives fine, just drives me mad.

 

[g8jka]

Idle has been OK again today even with the EML light on which is presumably the lambda again so I don't think that is causing the issue.

 

[BillyB]

@g8jka Did you get this problem sorted

 

[g8jka]

Not yet, still waiting for the issue to come back. If it does it will rule out a dodgy MAF as I am running around with @gookah's at present. If it doesn't reappear it will point to a dodgy MAF, but that one is currently on his and it's been fine.

I need to swap around the coil pack and do some scans but haven't had time. As the car drives fine it's not an issue that leaves me without a car so I'm in no rush. Will post an update when I finally get to the bottom of it.

 

[Mario]

It could be an air leak adaptations will move slowly with a small leak and only throw a code after sometime once the limits are reached monitor adaptations after resetting then and see how far and how fast they move, you can also see lambda values on inpa and see how they evolve ,

 

[g8jka]

Swapped the coil pack and spark plugs around about 4 weeks ago now and the rough values in INPA didn't change much. Did this with cylinders 1-4, then we gave the spark plugs a good clean and popped them back in. It's been fine for probably 95% of the time so we may have found the cure. Going to get some new plugs in a couple of weeks and hopefully all will be sorted. The rough values are a lot better now, still have a lambda light coming on intermittently but that can wait.

 

[fady]

I have been having some idle issues but only when cold, it goes completely once the car is warmed up.

The longer it idles the worse it gets, almost to the point of stalling. The only code I'm getting is a Lambda one which can't be causing it. It started not long after rebuilding the DISA which I though may be causing it, but swapped with a known working unit and it still does it. I've cleaned the idle control valve, intake hoses are not split, swapped the MAF for a known working one, spark plugs look OK. I did a rough idle test through INPA but this was once it was warm and cylinder 1 was giving a funny reading, but I don't understand any of this?

View attachment 93233

But, I've cleared the adaptations in INPA a few times now and every time it's cured the problem completely. Eventually it does come back. Any ideas what I should be looking for next?

 

[fady]

I have the same problem as you. Did you fix the problem yet?

 

[Sajk]

That cold idle issue looks exactly like one I had before changing vanos seals. In INPA I could watch the actual and target cam positions deviating exactly as the idle dipped. It usually started a minute or so after startup and went away when warm. But you also have an o2 issue and it's easier to fix that than rip the vanos apart

 

[g8jka]

I have the same problem as you. Did you fix the problem yet?

Nope Need to do a smoke test, it's had new spark plugs and recently a camshaft sensor which went dodgy. No change, but I haven't been chasing the problem really.

That cold idle issue looks exactly like one I had before changing vanos seals. In INPA I could watch the actual and target cam positions deviating exactly as the idle dipped. It usually started a minute or so after startup and went away when warm. But you also have an o2 issue and it's easier to fix that than rip the vanos apart

Funny you should say that as the problem started to happen not long after rebuilding the vanos. Maybe something was not put back quite right. No o2 issues anymore, that was solved a while back. Looks like the culprit maybe the vanos. Next thing will be a smoke test as that's easy. Did you change the vanos seals and cure the problem?

 

[Sajk]

Yup changing the vanos seals made that problem disappear and restored low down torque I did not know it was missing. Unfortunately I cheaped out and did not have the anti rattle kit installed as well. 8 months later...... it's coming apart again for vanos rattle. So i would urge you to do both if you do the seals and use quality parts and people for the job.

 

[Sajk]

I have looked in the thread but I don't see what code it's throwing. Check the codes in inpa which will give you the trim value and the deviation direction. If it's coding out at max negative trim it's highly unlikely to be a vacuum leak as that would show max positive trim as the dme adds fuel for unmetered air. Max negative trim where dme is removing fuel usually means over reading maf telling dme there is more air than there is or leaking/sticking injector. I just had this exact problem with a brand new Pierburg maf.

I am assuming you have double vanos otherwise the below might be incorrect for you.

On the idle to give a better indication if it's vanos find the section in inpa that shows you the actual cam position vs the target position then watch it on a cold start. Mine did exactly what yours does in the video and each time the idle dipped the exhaust cam moved on it's own. It has a big spring on the exhaust side which weak seals struggle to control.

On the adaption thing the only thing I can think of is that inpa will clear all adaption which includes vanos adaption.

Hope this helps.

Andrew

 

[g8jka]

Yup changing the vanos seals made that problem disappear and restored low down torque I did not know it was missing. Unfortunately I cheaped out and did not have the anti rattle kit installed as well. 8 months later...... it's coming apart again for vanos rattle. So i would urge you to do both if you do the seals and use quality parts and people for the job.

We used the X8R kit which is apparently good quality, rattle rings were also done. Low down torque increased slightly but I didn't see much other difference. Dual vanos. Will need to have a better look on INPA to see if anything will show on there. I get awful MPG in it even driving like a learner, barely 20 but I put that down to short journeys. It only does 3 miles to work and 3 miles back 5 days a week and doesn't get out much at the weekends. A longer run it's not as bad.

 

[Sajk]

Ok. What Codes is it throwing?

 

[g8jka]

Ok. What Codes is it throwing?

No codes at present. Haven't looked at the trim values yet.