vw polo cutting out - frustrated1
hi all thanks in advance for your help
i have a 1993 L reg polo fox coupe 1.05 litre
this occasionally dies in mid traffic with no warning (usually lifting the foot off the throttle or going down the gears (4 speed) from 30 to 70mph. more so after a run of 10 miles or more when things are hot, and possibly more on wet days..sometimes it will run for hundreds of miles without a hiccup
performance is not special but seems to run smoothly enough when starting and running
the hall effect unit on the end of the cam has been replaced
complete with rotor cap etc , new plugs fitted
coolant and antifreeze all changed in last 20k
service and oil change carried out at 95K new air filter etc (2 months ago)
new plugs, have checked under the bonnet for loose connections and sprayed cleaned fuse box passenger side. cleaned and sprayed all the plug together connections accesible.
it has been suggested to me it might be a fuel filter problem or fuel pump
however i dont know where the fuel filter is as i cant see one directly attachted to the single point injection mechanism under the air filter housing. i dont know if the fuel filter has ever been replaced , certainly not by me in 10K miles.
can anyone help or throw some ideas?


Cheers... the Frustrated polo owner
vw polo cutting out - howard
I had a 1983 VW golf with a 1272 engine about 8 years ago, with a hot engine, it would suddenly cut out, while it was still moving, I would try to restart by dipping and then releasing the clutch- to no avail. When I came to a halt, I'd turn off the ignition and then restart the engine on the key- fired up every time, this would happen 2 or 3 times a week.
The problem turned out to be a damaged cable going to/from the coil, a new coil and electric cable was fitted and the car went on to give good service for a few more years.
Could this be your problem?
vw polo cutting out - Adam Going (Tune-Up)
Howard's car was a very different beast, but certainly always worth checking all visible electrical connections, of course.

My first thoughts on your much later car would be to clean the throttle housing carefully (off the manifold to avoid cleaner/solvents contaminating Oxygen Sensor and Cat), and also to remove and clean the MAP Sensor, which I think you will find fitted directly to the side of the inlet manifold. Problems with the "throttle shut switch" / Stepper Motor and the throttle position sensor are also common, but really require an oscilloscope to test.

Regards, Adam
Whatever is rightly done, however humble, is noble.
vw polo cutting out - Adam Going (Tune-Up)
PS. The type of MAP Sensor that is fitted directly to the manifold is very delicate. Do not spray anything (liquid or air) directly into it. Drizzle some carb cleaner into it from a spoon, swill it around and then invert to drain. A length of small rubber pipe can be used to blow accross the aperture with it held inverted to draw remaining fluid out, or gently tap it down onto a clean paer towel until you see that no more cleaner is coming out.

Adam
Whatever is rightly done, however humble, is noble.
vw polo cutting out follow on - frustrated1
I forgot too mention that the car usually starts again no problem after switching off and on the ignition key, there no no rough running before or after this problem occurs
may i say thanks to all of you who have taken the trouble too reply
Merry Xmas
Cheers... the Frustrated polo owner
vw polo cutting out follow on - Big John
The symptoms sounds the same as carb icing, but this car is single point injection. It may be worth checking the warm air pipe fed from the exaust manifold anyway as I suppose the single point injection system almost acts as a carb.

Carb Polos are very prone to carb icing.
vw polo cutting out follow on - Peter D
This could be the fuel pump or its connection under the rear Drivers side of tank the filter is there as well but that fault would tend to limit rpm not cut the engine rapidly. Remove on clean the pump connector, grease and re-assemble. you say it immediaelt starts after you have had the ignition key off. Well are two or the relays behind the passenger glove box which you will have to remove. From memory one of these powers the ECU and Ignition circuit, I would be tempted to open them, if they have the removeable cover type, fiddley but possible and ensure the contacts are not burnt. Good Luck. Regards Peter
vw polo cutting out follow on - Adam Going (Tune-Up)
Good suggestion from Big John. You may also have an inlet manifold heater (known in the trade as a hedgehog, as it's suface resembles same, with lots of little spikes to disipate heat). This is situated directly below the single-point throttle body unit. Can be checked against specs for resistance of heater element, and for supply voltage. Or, simply, does it get hot - BUT BE CAREFUL, it does get VERY hot very quickly.

Regards, Adam
Whatever is rightly done, however humble, is noble.
vw polo cutting out - seb
hello,

Does the rev counter drop to zero when it dies ? (I had this happen on mine - '91 mk3 g40 - so vaguely similar model)
im my case this was diagnosed as a faulty hall sender on the distributor.....

at least if the revs drop to zero its more likely to be electrical than fuel related...

Cheers, Seb
 

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