My A4 2.8 is struggling to hot start...

[carlosvalderrama]

It's perfect from cold, fires up straight away. When it's warm and I leave it for just a few minutes it catches but doesn't make more than a couple of revs before cutting out. I can then either turn it on the motor for about 20 seconds and it slowly starts to fire, after which the throttle is very jerky and a blip sees a delay of about 1.5 secs before revving the engine. Or leaving it for a couple of minutes longer seems to help and it will fire up with more ease.

When running either hot or cold, it has started to hesitate if I prod the gas to get a burst of power at low to mid revs. It's okay at higher revs, but high revs tend to mask fuelling issues.

At a recent service I was told of weak signals from the lambdas, which could explain the hesitation when rolling, but I'd think that the lambdas had little to do when starting up.

I have new lambdas to fit, which I'll do, but does anyone have any ideas before I take it to have it's electronic mind read?


ta.

[istoo]

i kind of agree with you, fueling issue, would got an pull some fault codes from it and save any guess work.

[carlosvalderrama]

The new sensors have made it much crisper and stopped the jerkiness. It took a couple of days for the ECU adaptions to kick in though.

Tried the hot start last night and it was fine, but I'll see how it does with a few attempts.

[skid-mark]

if you still have problems try a coolant temp sender controls fueling from hot/cold easy to fit order one with a new seal they just push fit into a top housing or a coolant pipe with a plastic C clip to hold them in place and a multi-plug on the end

[istoo]

not sure on the B5 cars but the B4's unplug the battery for 30 minutes and the ECU would read fresh again, saves a bit of learning time. Glad that was a fairly cheap one!