Engine Idle Speed Hunting Up And Down.. Advice?

vw-po-low · Post by **vw-po-low** » Fri Apr 25, 2008 6:52 am

I've not long since brought my first car. 1997 Mrk4 1.0 L Polo 3 Door In Gray. I thought the buy was a bargin, bodywork is great with the acceptions of a few scratches. The interior is immaculate. 23800 On the clock, original miles. It cost me Â£775 at the auctions. She needs a few things tidying up. Main problem is the idle speed, she seems to be hunting up and down and dropping to very low revs 500 then it cuts out. I cleaned the throttle bodyout out yesterday at work, it was jamed full of crap and dirt, Since then she idle speed picked up to much, 1500 and even 2500 at times. At the moment its at 1500 i just tweaked thr throttle to get me by. The exhaust at the rear seems to be making like a poping noise. I've had some advice on it may be the Idle Speed Control Sensor or even the Fuel Pump Relay. Any suggestions? Hope to get her running better so i can go fetch a set of ATS Cup's at the weekend, make her better looking. Any help would be most greatful, Thanks.

NOZ · Post by **NOZ** » Fri Apr 25, 2008 11:56 am

Search 'erratic revs/idle' and you'll find a list of things to check. Lists pretty big, sorry!

The_phat_controlleruk · Fri Apr 25, 2008 1:21 pm

With mine I just needed the throttle body re-aligned after I cleaned it, this is a VAG-COM jobby which luckily I have.

Polo96CL · Post by **Polo96CL** » Fri Apr 25, 2008 1:30 pm

Yeah it needs a ECU reset I think, should be a pretty easy job for a garage.

The_phat_controlleruk · Fri Apr 25, 2008 1:35 pm

What happens is over a period of time, "s h i t" builds up on the TB, altering the position of the valve. The TB compensates for this, however, when you clean the TB, it doesn't compensate back (if you know what I mean) i.e. return to it's original position. This is when VAG-COM comes in, it re-alinges the TB. Mine did this when I cleaned mine, she would rev between 1500 and 2000, re-aligning the TB sorted it out. Although I could have got it completely wrong as I am not a mechamic and can only tell you of my experience, there are plenty of posts on here as it's a very common problem.

LeMeph · Post by **LeMeph** » Fri Apr 25, 2008 1:48 pm

Clean the throttle body out with some carb cleaner. then take the battery off the car for about an hour (just to be sure) That should reset the ECU. If that doesnt work then you may have bigger problems! Or need a VAGCOM as previously stated. You can do my suggestion yourself so sod it man just go for it int it!

NOZ · Post by **NOZ** » Fri Apr 25, 2008 3:15 pm

If the problems none of the above it could also be the temp sendor, distributor and leads, idle control valve or the part you mentioned yourself.

vw-po-low · Post by **vw-po-low** » Sat Apr 26, 2008 8:09 am

Cheers to eveyone for the help, dropping the Dub on the computer today at my dads work, also checking the overall condition of the car, seeing how its been brought from an auction who knows whats wrong with it.