Awful running

[dan_b]

Argh.
Last night, drove my car round the South Circular- first time I've driven it for about a week; last time it was absoloutely fine. Last night, absolutely awful.

Problems: what can only be described as not running remotely right.

Slightly lumpy tick-over.
Hesitant acceleration, low on boost at all throttle positions.
When the revs drop say, when changing gear, it very reluctant engine pick-up after bringing the clutch back in again - almost as if it's trying to stall. Makes for very jerky progress!
Holding the car at a constant RPM (say 3000), you can actually feel the car fluttering, it won't maintain constant speed and engine revs.

I've noticed a few threads round here in the last few days about running problems. I'm assuming I should be looking at:

Dirty MAF
Idle Stabilisation Valve
Split wastegate diaphragm
Boost leak

Any other usual suspects? I don't have access to VAGCOM, but would something like this be likely to produce fault codes?
How do I check all the above?
Sparkies were changed about 5000miles ago. Have a full tank of Ultimate. Car ran beautifully last week.

[Mikes2]

Could also be ignition related. Spark plugs, leads, coil, rotor arm etc

[dan_b]

Good point. Grh.
Is my best bet to try and pull some fault codes? How do I do it without VAGCOM?

[Mikes2]

S2central.net has a guide on pulling codes

[martinjs]

Definately check your plug leads Dan, They can crack at the ends which fit over the plugs causing misfires, also check that your plugs are tight, they can have a habit of working loose especially no 5 cyl.
Could be the old favourite boost leak of course.

martin

[Keeper of The Kitten]

Weather's been hotter than of late, def hotter than last week - did you get immediate problems or something that might be heat soak related?

Just a thought!

__MDC__

[4WheelDrifter]

I had a problem which sounds similar to this. The engine was only running on four. It turned out to be one of the connectors on an injector had broke.
To find which cylinder was the culprit I unplugged each one in turn. So unplugging the wrong one made it run on three, and the right one made no difference.

[BeckyA4]

Hey Dan, it sounds like a massive boost leak to me. Like a pipe split right open. Can you hear any whooshing noises when boosting?? Do you have aboost gauge in the car? Whats the reading when at idle?

[Jamo]

Hey Dan, it sounds like a massive boost leak to me. Like a pipe split right open. Can you hear any whooshing noises when boosting?? Do you have aboost gauge in the car? Whats the reading when at idle?

Becky should get on here more often she's talks more technical sense than her boyfriend

[S2 Ant]

Becky should get on here more often she's talks more technical sense than her boyfriend

I was just thinking that from another thread

[Mikes2]

if it's lumpy at tickover it won't be a boost leak

[4WheelDrifter]

If it's a massive boost leak as Becky says, it could also be a vacuum leak at idle.

[dan_b]

It doesn't sound like a boost leak - there is no noticable whooshing or hissing noises (well no more than usual with a cone on instead of the 3B airbox).

It happened literally from turrning the key on Thursday - which was a significantly hotter and more humid day than any we've had this year. Engine and oil temps were fine on the gauges.

I'll start with the obvious and check the HT leads and plugs - I might be having a visit from one of our fantastic S2forum members this weekend to give it a VAGCOMing, so maybe that might illuminate it if it's not as obvious?

[audiman]

if it's lumpy at tickover it won't be a boost leak

Why not?? Try pulling a hose off.

[dan_b]

Ok - took the ISV out - rather black in there, so gave it a good squirting with WD40.
Took the MAF off, the wires are all still nice and clean.
Took all my sparkies out - 1, 3 and 5 were all what I would describe as "loose". I took a picture -all 5 are in this same condition, they look ok don't they? I changed them about 8,000 miles ago. Plug leads look ok, no visable signs of damage or any arcing or anything.

So, after doing all that lot - tick over seems smoother, but on the road, still getting this hesitation feeling after gear changes. It doesn't feel like the hesitation issue that Honahon had (which turned out to be a dodgy coilpack, and from that I'm extrapolating that to mean that I'm firing ok on all 5-cylinders), so what else could it be? Couldn't see any visable signs of any split hoses, and it definitely is not sounding like there's a boost leak - no noticable hissing our air escaping sounds.

Any other ideas? How do I check the wastegate diaphragm? Will be checking out VAGCOM for fault codes this week...