Surging Revs at Idle

[Dave_R]

Had this problem since winter and now its doing my head in. The car surges between 900-1500rpm when idling, sounds like it’s going to drive off by itself, I have tried cleaning the idle control valve and still had the problem even swapped it with my mates and my car still surged where his didn’t with my control valve.

I have tried VAGCOM thanks to PhilW and it found no fault errors at all and when I went to show him what I was on about the car idled fine, as what usually happens when you go to show someone.

I know it can’t be the control valve and VAGCOM would say all the sensors are fine but I’ve been told that the temperature sensor will still give a positive read out when it is still faulty, could this be the problem?

Or have someone got any ideas what could be wrong?

 

[andyj]

check all of the vacum pipes to/from the airbox and also the inlet manifold/throttle body.

Check the ends of the vac pipes to, they can some times split etc.

Also, try cleaning out the throttle body with carb cleaner, they sometimes get really gunked up etc.

Just a few things to try for starters

Trying to remember what I did when I had simialir probs with my 2.0 16v Cordy !!! Will check for my posts about it

Andy

 

[andyj]

http://www.seatcupra.net/forums/showthread.php?t=64893

 

[alimac81]

Have you taken it out for a good drive? i had this exact same problem on mine after i finished rebuilding the engine, tried checking all the pipes, but i decided to take it for a drive home and now its fine

 

[Dave_R]

Cheers AndyJ, gonna try some carb cleaner in the throttle body now and alimac its been happin since the start of winter so been driving it a lot since

 

[alimac81]

Could try driving to france?

 

[Dave_R]

lol knowin my luck I would break down driving there or get lost

 

[Dave_R]

Right.... all the pipes and sensors look fine, I have sprayed Carb Cleaner into the throttle body and the engine is still surging

I wanna get this sorted asap so I can do some mods to the engine

 

[andyj]

idle control valve..... sits underneath the black plastic cover that the ignition leads clip into....

give it a good spray with carb cleaner again...

 

[Dave_R]

Gave that a good clean about 3 weeks ago and also tryed my mates on my engine and it still surged and when he tryed mine in his it was fine

 

[andyj]

Oh yeah, forgot you said that earlier !

Ummm...... other things to try......

 

[andyj]

Coolant Temp Sensor maybe.... if the ECU thinks that the engine is hotter/colder than it actually is, then it will either under/over fuel...... possibility

 

[Dave_R]

That’s what I was thinking a sensor maybe faulty but I plugged in the VAGCOM and it found no faults

Could the temp sensor still be giving a positive signal so the VAGCOM thought it was fine

 

[Red Ibiza VR6]

I reckon the temp sender. The one with the 4 wires on it. Its related to the choke, so that could be the surging. Also check the wires to that sensor, as it could be a dodgy wire.

Good Luck.

 

[d4ve]

also there wont be an error thrown up by the CTS as its still working just not at 100%

a dodgy CTS tends to affect mpg as well though - noticed any difference in how quickly u gotta fill tank?

if its not that id say an air leak

 

[Dave_R]

Brought a Temp Sender today but can't see where it goes... any advice

My mpg is a bit lower but I put that down to the mods and the way I've been driving it lately.

 

[alimac81]

fuel pump, or filter?

 

[edc]

Dizzy end of cyl head. It can show up a fault code though.

 

[traumapat]

im sure youve tried this but does still misbehave with maf unplugged?

had a similar thing happen, surging before engine warms but all ok once warm and that was a faulty temp sensor. but it idled ok.

 

[Dave_R]

That Temp Sender I got from VW because SEAT were shut all day saturdays, its the 4 pin type but I have looked and looked and looked again and can't find where it goes?