Hello everyone,
I have a 1999 Mk4 Polo with the 1.0L (AER) engine. It's done 65K miles and has been regularly serviced.
It always starts first time, but regularly stalls about 20 seconds after pulling away, usually when the engine's cold, and usually in cold weather. It drives away nicely, but then I can feel it losing power, even with my foot on the floor, and as soon as I take my foot of the accelerator the revs drop and it stalls. It's not easy to restart, but if I leave it 2 minutes, it's fine.
But now it's started doing it on warmer days too.
And today, it played up on the motorway at 70mph (when the engine was fully up to temperature) causing the car to slow down to about 40mph for a few seconds... then it was fine again all the way home.
We have already:
(1) Changed the engine temp. sensor,
(2) Cleaned the throttle body,
(3) Replaced the inline fuel filter (after removing the pump's mesh filter to allow any debris to be flushed into the inline filter).
(4) Changed the HT leads, distributor cap and rotor arm.
There are no fault codes stored.
Any ideas? It's changing from a nuisance to a danger now, so I'm keen to get it sorted as soon as possible.
Thanks,
Nick.
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My first thoughts were classic symptons of engine coolant temp sensor faulty.You say this has been changed but did you fit a genuine vw part.?I have recently seen relacement non genuine temp sensors giving a totally incorrect signal to engine control unit.
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Yes, genuine VW (blue ring), bought it from the local dealership myself, having quoted my VIN etc.
The other thing I've seen mentioned on the web is the relay that controls the fuel pump (191 906 383C). What do you think?
Nick.
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Hall Senders are quite a common problem but the symptoms you decribe don't immediately indicate this to me. Maybe worth trying if all else fails.
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Nick
The cold running problem sounds like the wrong oil.
The m-way fault could be many things; get the fault-codes read again.
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Could it be that the fuel pump is U/S after having passed the debris from the tank for you?
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just a thought??? I think on the older air boxes they used to have a air direction flap. one way would let outside air in and other would let air in thro the exhaust manifold heatshield. when driving in cold temps if the flap stayed in the wrong position butterfly in the carb or monojet unit would ice up causing running faults. sounds a little like what your symptons are but im unsure weather your model will have that system. maybe worth a look!?
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used to have a 1986 polo with the exact same symptoms (i know there's an age gap!). had the carb cleaned which helped for a while but had to keep having air blasted through it to keep it clean as the engine kept cutting out. everyone i spoke to said it was a classic carb fault on vw polos (as described by jonah1) and recommended changing the carb. regarding the motorway incident, had a similar incident where the cam belt became worn because the water pump was fitted too tightly and was slipping.
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is your fuel pump making noises, have you by any chance modified the air filter
{txt talk removed and replaced with proper words because unlike a mobile phone you aren't restricted to 160 characters here!! - DD}
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