1.8 tfsi rough for 30 seconds.......

[ETHel]

I have done a search on the forum and can't find anything as specific as this fault, unless I missed it. If that's the case please direct me.

Fault - cold start engine runs rough for 10 to 30 seconds then settles down and all is well.

If I unplug the maf sensor it's fine, I know what you're thinking but it's not the sensor. I bought a genuine used one, a genuine new one and even tried another from a working car, same result.....After the "alloted" time I can plug the sensor back in and all is fine, drives as expected. I've had pcv problems with other cars so I did replace this one, the old valve is okay - the blow and suck test.

There are no codes or engine lights. Tried both my cheapo reader and a decent launch one.

Car has had spark plugs recently during the service (fault was there before). No oil in the spark plug wells. Bought a used bosch coil pack and changed it on no. 1 cylinder. I thought about getting a new set of coil packs but don't want to end up spending a load of money on parts that are not needed. I don't expect a 'parts cannon' job to sort this out somehow. 

Checked a few times for leaks and done the normal checking including cable checking for continuity and connector drag test. Engine not using any coolant, oil seems fine also. I putting in E5 BP Ultimate or Esso Synergy Supreme+ 99

As far as I know there's been no remapping - how would I tell anyway? The car has standard parts, no boy racer upgrades.

It just bugs me! I'd be most great full for any ideas on this one.......

 

Edited yesterday at 12:33 PM by ETHel

[Rybrook]

Is that not normal for a cold start?

My 3.2 has a lumpy raised idle of first cold start. I don't move off until the revs drop down. 

[ETHel]

Never had a car that idles rough when cold like this engine. Never had an Audi 1.8 before so don't know what is normal.

I guess to me it sounds like multiple random cylinder misfires by the 'noises' and 'feel' of the engine. Why should it behave with the maf sensor unplugged?

I'd love to know the engines theory of operation during the startup procedure. What's happens during the first couple of minutes.......

 

 

[Rybrook]

I can't really comment on the tfsi as I have a 3.2 vr6. 

With mine it's secondary air injection to warm the cats, I get raised idle and slightly more vibration.

If it behaves with the maf disconnected then there is a problem with it.