Intermittent brief engine stutter on 1.4 TDI 90

D

digiblue

Member
Hi all,

Our 2004 tdi 90 A2 recently reached 60,000 miles and we had its timing belt changed a few weeks ago by a reputable ex-Audi mechanic.

A few days later the car began to idle roughly after a 5 minute journey from being left overnight. If it makes any difference the car had just had a full tank of diesel after being run low the day before.

The rough idle resolved itself after a few minutes, but the A2 now has an occasional engine stutter or misfire. This happens in 2nd or 3rd at around 2000rpm and lasts for a few seconds. It can happen a few minutes after the car has been started or after a long motorway journey. Since the rough idle there have been no warning lights or error messages on the dash. I've run some diesel redex through the tank, but it has made no difference. The A2 was serviced around 10,000 miles ago, including a new fuel filter. It is used for regular 100 mile motorway runs and has so far had the full 25,000 or miles between variable services.

I am wondering if it is likely that something which had to be removed or disconnected to reach the timing belt may have been 'upset'. eg. a wiring harness or hose.

I haven't yet investigated beyond visually checking that there was nothing obvious wrong under the bonnet.

Any ideas where to start? I am guessing a diagnostic code read.

Thank you
Andrew
 
Thanks for the response ULP. It is under light acceleration around town that we've experienced the stutter. When the stutter next occurs i'll try putting my foot down to see if it makes any difference.

ULP said:
Sounds like it could be the fuel pump at fault - under load the pump is unable to deliver the fuel required. Try accelerating at a light throttle opening in the lower gears and then repeat giving it the berries; I suspect the former will be fine, the latter will recreate the problem.
Click to expand...
 
another update. i put through some redex for diesels, it has made no difference. the problem is still there, fortunately it doesn't seem to be getting much if at all worse. also tried putting the pedal to down hard when the problem stutter occurs, it doesn't seem to make any difference. it's apparent that the problem occurs only during smooth accelleration, but perhaps this is just when it's noticeable. i think it's time to see if there are any fault codes stored.
 
Does the stutter occur at around 2000rpm by any chance?

If so, I suspect a MAF fault - I had the same thing a while back. Strangely, I never replaced the MAF, but the stutter went after a remap!

Cheers,

Mike
 
Thanks for the reply Mike, yes it occurs at around 2000 - 2500 RPM. Might pop off the maf and give it a clean with throttle body cleaner.

Did your diagnostics equipment show up a MAF problem when it happened on yours?

A remap sounds like an interesting solution!

Skipton01 said:
Does the stutter occur at around 2000rpm by any chance?
Click to expand...
 
No, no faults stored and I never cleaned the MAF either.

The other possibility is the turbo - this is the rough point (2000rpm) at which it kicks in. Check that all the hoses (the small black rubber ones) around the back of the engine bay are connected and free from splits.

A remap will probably cure this and will certainly give you a big smile!

Cheers,

Mike
 
Also check the large hoses, especially the ends, on the driver's side as these have to be removed to change the cambelt.
 
Thanks both,

I did have a look last night and couldn't see anything untoward with the hoses. I removed the insulation from the top of the engine and checked both the matrix of thin hoses that lead from a module on the left of the engine bay and the wider air inlet hoses. I'll look more closely at these again though and report back. I guess the thin hose from what looks like a regulator on the turbo is one to pay close attention to, as well as any of the wider hoses on the engine side of the maf.

I must admit that I can hear the turbo spinning up and sounding like it is stumbling when the stumbling occurs. I assumed this was caused by the stumbling rather than the cause of the stumbling, but maybe not.
 
just an update on the stutter. Some months ago the A2 went on Spike's VAG COM and no fault codes were reported (apart from a drivers door lost communication).

The stutter is still there between 2000 and 3000 RPM, it gradually started to get worse. After a MAF clean with carb cleaner and some premium diesel it improved, but is still there.

I recently discovered that disconnecting the MAF stops the stutter. I'm still reluctant to spend £100+ on a new MAF, as disconnecting it probably puts the ECU in 'safe' mode which could itself be eliminating the stutter? I'll probably trawl ebay for a cheap MAF, maybe just the sensor which is screwed onto the MAF cylinder.
 
Keep us posted.

My old engine did this, before it imploded. And now my new engine is doing the same. I'm wondering about MAF. Is there a good place to get them checked?

Al
 
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