Googling implies this is a fairly harmless, common problem, but I know there are some long time VAG PD owners on here, so just wanted some reassurance.
2002 Golf GT TDI 130. Starts instantly (literally half a second after turning the key), idles at the right speed, but has a slightly "lumpy" idle quality for the first minute or so if the car has been standing for more than half an hour or so. The revs stay steady according to the rev counter, and the engine sounds steady, but there's an intermittent gentle "rocking" from the engine, as if it has a slight misfire.
Drives perfectly though, and as soon as the engine is even slightly warm, the problem disappears. Seems to be in good condition otherwise (goes well, economical, not smoky etc).
Any thoughts?
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The obvious one is the the compression is down on one cylinder. Could be down to valve clearances, or are they hydraulic tappets? does it smoke while running lumpy, white or light blue?
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Hi Peter,
Nope, runs perfectly, pulls perfectly, no smoke. If you pick it up off idle, it smooths out, and there's no trace of a misfire when driving. It's only on idle, and only for that first minute or so.
Starts literally instantly on the key from hot or cold too, and straight onto four cylinders. Even when this thing is happening, it doesn't sound like it's running on three. It's very irregular.
Not sure if they're hydraulic tappets, but the engine sounds fine. No ticking or other strange noises.
Cheers
DP
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My Passat PD130 used to do this when lukewarm or stone cold, virtually from new (the engine was mounted longitudinally rather than transverse but you could still feel it).
It would idle smoothly when fully warmed up, but as you've probably found out the PD motor does cool down very quickly, especially in the current ambient temps.
I remember that when I cleaned the MAF sensor plug with contact cleaner it helped smooth this out, I used to clean the plug by unplugging & replugging 4-5 times every six months or so.
It might also be a very slightly worn injector nozzle which is giving a touch too much fuel at idle.
I don't think it's anything to worry about, to be frank.
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My 1.9 105 PD's have always done it from new. Its feels like a petrol engine would if it missed one cylinder every 10 seconds or so. I suspect its engine management effect of some kind.
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Thanks guys. As I hoped. :-)
AE - that's exactly how I'd describe it, except maybe more like 3-4 seconds on average, but with variable (and unpredictable) gaps.
Yes, I had noticed how rapidly this engine cools, and how long it takes to warm up. On the test drive, I actually thought the gauge had packed up until it eventually hauled itself up to 90°C
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I have the same engine in my A4 and does exactly the same thing. If you sit on idle from cold for a minute or so I get a noticeable change in engine note with an associated click from somewhere and all is well. Mine has done it since I bought it at 110K and has nearly 155K now and not given any trouble.
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