Help - rough / hesitant when warm!

[haaran]

I've started using my S2 Avant as my daily drive for the last couple of weeks now and it's been driving fine, although not as punchy as a month or so back (i'm thinking/hoping the weather may have something to do with that!).

Anyway, a couple of miles into my commute this morning, I could feel myself shaking in the drivers seat whilst standstill in traffic (belly was wobbling all over the place). The engine was sounding a little rough too. On moving, the car was very rough and noisy at low revs, and was hesitant like when you're jump starting an old battery or trying to start the car when it's ran out of fuel. Once it picked up some revs, it would get going, however, there was very little power there and i'd have to drop gears even for the slightest inclines. I could also smell burning rubber and occasionally fuel. It's doesn't cough/splutter excessively but definitely isn't sounding right when warm.

Had a look under the hood when I got to work but couldn't notice anything obvious apart from the engine shaking a lot more than usual.

After work, I started the car and all seemed 'normal' again, for the first couple of miles that is, and then it happened again.

What can it be?

Cheers

[archiboy24]

This sounds a bit like the problem I've had in the past. How does it idle when the engine is hot? Does it hunt up and down? In any case, this sounds to me like the O2 (Lambda) sensor is fading out. When was it last replaced?

[haaran]

The idle is quite stable in this situation. Occasionally it does fluctuate but has done so previously and normally sorts itself out quite quickly.

I couldn't say when the lambda sensor was changed. I've not changed it as i've only had the car a few months.

Is there anyway I can check it?

[archiboy24]

Try driving around with it unplugged for a while. If it behaves, it's time for a new O2 sensor.

[s2_bo]

You can just remove the fuse for the lambda to see if that makes a difference. It could also be the multi function temp sensor playing up although it sounds a bit extrema for that.

[BrianSmith_S2]

I would try the following

1. clean the maf
2. check the spark plugs for fouling or being loose
3. check the earth connection at back of the can cover on the left just under pipe into throttle assy

hope you get it sorted

[haaran]

Right...today the car still has a problem but it's changed slightly. At low speed/revs it's still horrible but if I floor it, it seems to go okay'ish. Disconnecting the lambda sensor from at the two plugs made no difference and disconnecting the MAF made it worse. The earth wire at the back near the throttle has a slight nick in the sleeve but otherwise seems fine. I can smell fuel still and the already poor economy has taken a nosedive. Is it possibly a leak somewhere causing all this? I guess a diagnostic is called for.

The cover behind the drivers side headlight directing air to the airbox is missing (anyone have a spare?). Will that contribute to the poor behaviour? There's also a little oil leak at the back of the engine dripping onto the plug at the back there. Is that something to worry about?

To add to the problems, whilst I was tinkering with things under the bonnet, the power steering fluid decided to start spraying out from the vent in the cap (the car was warm and the engine was running)...what's happened there?

Also, can someone explain the fusebox to me. There are fuses labelled up to number 30 or so but the row of fuses in the fusebox only goes to 21 and few more beneath. Where are the remaining fuses?

[SteveRobb1973]

Try driving around with it unplugged for a while. If it behaves, it's time for a new O2 sensor.

I have a similar (sort of) problem with hunting a little when hot. Where is the Lambda sensor?
Steve

[archiboy24]

I have a similar (sort of) problem with hunting a little when hot. Where is the Lambda sensor?
Steve

The Lambda sensor is screwed into a bung on the down pipe and should have three wires coming from it. It connects at the firewall.

[archiboy24]

Right...today the car still has a problem but it's changed slightly. At low speed/revs it's still horrible but if I floor it, it seems to go okay'ish. Disconnecting the lambda sensor from at the two plugs made no difference and disconnecting the MAF made it worse. The earth wire at the back near the throttle has a slight nick in the sleeve but otherwise seems fine. I can smell fuel still and the already poor economy has taken a nosedive. Is it possibly a leak somewhere causing all this? I guess a diagnostic is called for.

Hmm. Could possibly be a vacuum leak. Check all the vacuum hoses that connect to the intake manifold.

[haaran]

Been having a read of 'similar' issues...is it possibly POS, coils, boots related?

Also, my MAF has one less pin than the plug...is that right?

[T2Andy]

I think the number of maf wires to pins is ok ,i would take your s\plugs out
and see if any are black or differant to the rest sounds like a cylinder is not
firing as is should ,something is breaking down when hot .

[T2Andy]

Like Brian said

[haaran]

Getting worse!!

It's not a hot or cold issue anymore, the car's just horrid to drive all the time now. Had a look at the plugs today and what a sight. All of them where drenched in oil and a couple of the rubber boots were cooked. It seemed to be that number 5 had the most damage gradually becoming less towards the front of the engine. Is this the same reason for the oil leak at the back of the engine and is it the rocker cover gasket or something more than that?

I cleaned the plugs and removed as much oil as I could from the boots and the holes in which they go. I was hoping this would show some improvement in the running of the engine but it didn't really. The inside of the cover also had browning again worse towards the back. Are the coils potentially knackered?

Suggestions for what to do next appreciated.

Ta

[stevieyid]

Have you checked Vag come for any codes? I had my coils go and similar symptons but mainly at WOT not all the time.