1.6 BGU Engine slight misfire at idle

[piehole1983]

Hey everyone,

I'll try to keep it short and to the point.

I bought a 2005 A3 1.6 with the BGU engine recently. Changed the water pump and timing belt immediately. A little later did the oil, filters, plugs etc. Before I did those I noticed it would misfire slightly at idle. Stuck VCDS on and watched the misfire counters, cylinder 4 seems to be the culprit. The plugs I removed weren't very old by the look of them but they were very white, indicating a lean mixture I guess. The new plugs don't seem to have made much difference, if any.

MAF problem perhaps? There's no faults stored relating to the MAF at all.

 

[piehole1983]

Slight update to this one. There's no MAF on this engine, it's using a MAP sensor instead. I cleaned the sensor and throttle body with carb cleaner as they were both pretty stinky. Slight improvement in idle stability but sometimes a very noticible misfire. It seems to be worse when the weather is warmer, around 13 degrees is the best I've seen so far. On the cold days it idles much better, near perfect I'd say.

 

[marci4]

Hi, mine's a 1.6 BGU as well and I also have the odd misfire when idling. If you read around the net, it looks like these engines just behave that way. 640rpm on idle is just a little too low but VAG wanted to lower the emissions. Apparently Seat has performed an ECU software update on their vehicles which apparently raised idle rpms slightly and that solved the problem.
I emailed local Audi dealer to ask them if they would be able to do something like that but haven't had a reply...
Did timing belt along with water pump as well. Throttle is yet to be cleaned...

What I have read is just turn your AC on which should raise the revs on idle slightly and then it should not misfire

BTW. What is your ECU software version?

 

[piehole1983]

I'd need to look at my scans to see what the sw version is. I'll do that tomorrow.

I did try running with the AC on, it does make a difference but the misfire is still there. It's weird that most of the time it's perfect and then other times is pretty noticible and annoying. Always cylinder 4 as well