Erratic Engine Idle

**kevian** · 11-12-2011,12:40 AM

Hi guys, i've bought my son a 1.0 P Reg Polo which seems to run fine, except for :-

The car does not idle very well at all. When coming to a standstill, the revs rise to around 2000 and unless at a complete standstill, will not drop or settle. Even when the clutch pedal is pushed in fully, but the wheels are still turning, the revs will not drop below 2000 unless the wheels have completely stopped turning.
I've noticed that the temp gauge does not move above 70 and i have seen in another thread on this forum that changing the temp sensor sorted the problem.
I just wondered why the revs don't drop unless the car is at a standstill.

Cheers

Kev

**Crasher** · 11-12-2011,01:18 AM

First of all have the car scanned for fault codes, the the throttle body needs removing for cleaning front and back and then it has to be set up with a diagnostic computer.

**kevian** · 11-12-2011,01:29 PM

Thank you for your reply, could you give me an idea of the cost of doing what you suggest at a garage please? Does the wheels rotating have an influence on engine revs?

**Crasher** · 11-12-2011,09:18 PM

Going by what I would charge you are looking at £30 for a code read and £65 for throttle body removal, chemical and nonabrasive cleaning, reinstallation, adaptation clearing and throttle body realignment. The ECU can see that the car is moving by the road speed signal and certain software versions raise the idle whilst the car is moving for a variety of reasons including emissions and power take up smoothness. Often I clean the throttle body of a 6N Polo and this feature starts up when it was not there before due to dirt accumulation. I find that if I put the car on an incline but foot off the clutch and in neutral, then allow the car to roll forwards, within 1 or 2 Kph being shown on the ECU live data screen, the revs increase by around 300rpm.

**kevian** · 13-12-2011,07:12 PM

Once again, thank you for the reply. Would you say that, having the throttle body removed, cleaned etc as you describe above, would resolve the high revs?

**Crasher** · 13-12-2011,11:51 PM

From what you describe, yes, but I cannot guarantee it.

**kevian** · 14-12-2011,06:26 PM

Nice one, as it's not really suitable or safe for my son to learn to drive in it's current state. I presume I just call your garage during business hours to make an appointment. Will it take long, or is it a sit a wait job?

**Crasher** · 14-12-2011,11:59 PM

Yes, just give Roy, John or myself (Steve) a call on 01159785740 and book it is. From Heanor we are about 20 minutes down the A610 towards Nottingham city centre and we are about 300 yards off the A610.