VW Polo engine revs - "hunting"

The message from "Scott Mills" contains these words:

Really a carb and not a throttle body with single point injection in it?

I've just received my 1.6 GL (carb) 99 V polo back from the garage for a 50k service. The work been done is:

new plugs air, oil & pollen filters tighten clutch cable tighten h/brake cable

before I went in, engine would idle at 950rpm. Now it "hunts" between 1000 -

1300, and settles at 1200rpm before dropping to 1000rpm after sometime. There has been no degrading to the performance during general driving.

What have they done wrong? or is the ECU learning the new plugs and general set up of the car again and will this sort itself out? I guess I need to know before I shout at them!

Cheers

Scott

In news:6bCGc.466$ snipped-for-privacy@newsfe1-gui.ntli.net, Scott Mills slebbered:

Carb + ECU = Nada.

It won't be a carb and if it is - it won't have an EMS.

Graham

yes

The message from "Scott Mills" contains these words:

The rest of us are almost certain it hasn't! Seriously, only a few cars spluttered on with carbs after about J-reg - things like the Metro which had a carb and a cat - not an easy combination. Yours must have a cat at that age - and carbs are as rare as hens' teeth.

It's possible that something has been disturbed during the service - perhaps under the air filter housing. Some cars have a clutch sensor which tells the ECU to up the idle slightly when the clutch is down. Don't know if your car has this but if it has it may be related to fiddling with the clutch cable.

Of course - it may also be a coincidence - they happen all the time.

Ok you got me here then... I'm almost certain it has a carb.

What could the problem be if it is carb'd - vacuum leak? would this have been caused by the service?

The biggest problem would be finding the git who's sold you a 99 car with an 89 engine in it. However even if it is fuel injected it's probably a vacuum leak & they've probably just not reconnected a hose.

Firstly it wont have a carb being a 99. It will be single point injection.

See if it calms down after 2-3days- they have disconnected the battery during the service, but dont know why..? If not, take it back to the garage.

Tim..

No.

D'oh, is that what I sent, "No." Oops, my bad - I went into detail about Polos using fuel injection!

/blushes/

Perhaps - does the handbook give a nominal idle speed?

950 rpm may well be a bit high, ours idles at 850 - 900 rpm... but it's a completely different engine! :)

Apparently not

Well it has settled now. Idles at 1000rpm. I still think that is a bit too high though for a modern engine?

Is too high yes. Hot engine should be at 800-850rpm according to my data.

Definately sounds like the ECU has lost it calibration and/or thrown a wobbler. Having the throttle body re-aligned will sort it. (unless the TB has gone "faulty"- and several have been just lately :( )

Tim..

Thanks for all your help. I shall keep an eye on this and will probably take it back to the garage next week.

Scott

Just a follow up to close this off.

The car went back to the garage today. Apparently they had over tightened one of the filter assemblies and it was touching the throttle cable causing the high revs. Once sorted it settled down to its usual 850rpm at hot idle