'95 Polo GL 1.6 - high idle speed & rev's fluctuating

[tobs_pj]

Hi all

Wondering for any tips on the trouble shooting the following problem

when in idle the rev's keep fluctuating- 1500rpm then down to below 800 rpm then repeats its self, it can cut out when taking off, unless the revs are kept very high

when the driving it at low rpm the car can be very jerky


I'd been told that its the Single point Injector unit that needs to be replaced

any have this problem before

[david burton]

welcome aboard

there are a host of problems with idling on the mk4, and most are due to the temp sender unit (do a search). you can do a lot worse than to clean the throttle body (very easy to do) and giove it a darn good flush out with redex.

Also, an ECU reset might help a little.

[tobs_pj]

thanks for the feedback

my mechaic recommend replacing the whole fuel injector unit (throttle housing, injector & steper motor)
other people have told me that more than likely its the steper motor thats faulty, this iw what controls the revs in idling
but its safer to replace the whole injector unit (and quicker)
i've source a second hand part for £50, so hopefully it will do the trick

[Speedlaw]

Try the temp sender first. It takes 30 seconds to fit and only costs 20 quid.

[BenMMellor]

one of the first things I would do before spunking a load of cash is to do an ECU reset.

Leave the battery disconnected for about 15 mins - half an hr.

Essentially the ECU wil re-learn the fueling and idling. I was about to spend £400 sorting out the throttle body and temp sender etc.. My mechanic had the battery disconnected whilst he did the cambelt.. When he connected the battery back on the idling issue was fixed.. and stil is 8 months later !!