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Discussion Starter #1
Hi,

Having read the site and the FAQ I've eliminated many of the usual suspect (MAF sensor, etc.) for this.

Symptom is that the car (TDI 130PD with 150k on the clock) is fine on A and B roads from cold start. Pulls strongly and is completely normal. Takes me 15 minutes to get to the motorway so the car is good and warm by that point.

Accelerating to usual motorway speeds I get an intermittent juddering/stalling sensation. Initially its a little similar to the sensation you get in cruise control when going downhill. If I keep my foot down this usually goes away but on one occasion recently it got very bad and after 30 seconds switched on the traction control warning light. After that point the car sounded very rough (almost like it was on 3 cylinders), shook at idle, and wouldn't go above 50mph. No obvious smoke or smell of fuel, and the back of the car isn't sooty. Tract control light cleared by a stop/start and car was fine immediately after that for the rest of the run to work.

From past experience of petrol cars, Golfs included I would normally first check for vac leaks and intake manifold sensors (I remember my Mk2 GTI doing similar and that was due to a loose intake sensor connection).

I've checked with VAG-COM and I get a 17664 code - engine temp sensor short or open. Its reported as intermittent and doesn't always come back each time I clear the codes. No other codes reported. Is the engine temp sensor going to cause this? The juddering is really heavy - like you get if you kangaroo a car, everything shakes.

I've also logged my journeys home (around 30 minutes) using VAG-scope, looking at the MAF sensor and intake pressures. MAF sensor traces keep reasonably good step with each other although the first data figure will not go above 850 (think that's the expected figure) whilst the second figure will go into the low 1100s on hard acceleration. I think that points to the MAF sensor being OK?

I've seen references to the injector wiring loom going bad and causing something similar, would I expect to see an error code logged for that though?

Seeing as the temp sensor is a cheap job I'm going to get that done along with a basic service - fuel filter hasn't been changed recently for example) but I'd welcome your thoughts before I talk to my mechanic on Monday morning.

When it doesn't do this shuddering the car seems to have the performance I would expect - I can stick it in a high gear at 1000rpm and put it under heavy load, it revs to the redline, and for testing purposes its easily gone into 3 figures on a quiet road. Starts first time every time.

Many thanks in advance.
 

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I don't think the engine temp sensor would cause that. You're right, juddering is normally a boost leak. It looks like the MAF is OK. The fuel filter is a good start but I would have thought the problem would be more consistent. Please post a follow up if those 2 things make any difference.
welcometomyturbodies
 

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Discussion Starter #3
Fixed now.

Got the basic service done, no vac leaks and got the temp sender replaced. No improvement in the problem but got a new fault code indicating an electrical fault on cylinder #1. replaced injector wiring loom (£50 for the part plus an hours labour) and now it's all absolutely fine.
 
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