buckshot

First post here ... I attempted a search on this topic to no avail ...

2006 A4 2.0T with Tiptronic.

When the engine is cold (much more pronounced when REALLY cold ... as in the winter months) it pulses under light to moderate load - as in a normal cold acceleration. When at constant speed (cruise control on) no matter what that speed is, the pulsing goes away. When gaining speed the tach jumps up and down about 150rpm's. This goes away after about 5 minutes or so (probably longer when even colder).

So if I am slowly accelerating in town up to 60km/h, manual upshifting, the engine constantly pulses as the rpm's increase ... very anoying. If I stop accelerating and simply hold my speed, be it 25km/h or 50km/h or whatever, the pulsing stops.

Any ideas???

Cheers,

Ted

a4audi4fun

Intake tumbler flaps or PCV would be areas I would check. Codes might exist even though the CEL doesn't turn on.

buckshot

Thanks ... the car has been doing this for about a year and about 3 months ago I replaced the PCV (had a whistling noise coming from the engine ... old one had a small tear in it). This didn't seem to affect the pulsing though.

theedge111

I'm noticing the same thing in my B8 S4...I've got a service appointment at the end of the month, SA told me over the phone that it sounds like the spark plugs need to be changed?

buckshot

Would bad plugs only cause this problem when cold?

Intake tumbler flaps ... what do think might be going wrong with them? (I ask not knowing at all what they are or what they do when working correctly!)

theedge111

I have no idea, it happens when the temps are below zero in the morning and then only for about 1/2km and then runs fine.

I start the car, and only let it idle until the rpms drop, then drive off, never going above 3000rpms until the oil is fully warmed up (exactly what I did for my B7 S4 and never had an issue with it)

a4audi4fun

Tumble flap description

buckshot

Thanks for the graphic - helpful. I'll be sure to mention it to my mechanic when it goes in next.

kowrek

Let us know what he says. I noticed my 2007 2.0T doing this the other day. I figured it was just helping warm up the engine. Or, was maybe because I had the seat heating on, and the alternator needed some extra juice?

multiphrenic

Where did you find this? Where can I find the whole book??