intermittent eratic idleing

[jimmy2006]

have a mk3 cupra T with a revo remap and a dumpvalve, sometimes when the car warms up the idleing sometimes will jump up and down from about 800 - 1150 rpm on tickover, I have replaced the coil packs recently, pluggs on last service, new lamdba sensor, all pipes and hoses appear to be connected with no visual leaks. Vag.com doesnt bring anything up. Just wondering if this is normal or there may be a small problem somewhere??

 

[acidstrato]

not really a problem bud, its just secondary air injection running...assuming it settles eventually around 800rpm

 

[jimmy2006]

yes it does, thanks. was just making sure. as soon as you press the accelerator it settles.

 

[Essex_Cupra]

yes it does, thanks. was just making sure. as soon as you press the accelerator it settles.

I had the same problem for a week or so just had the minor service done and replaced 4 coils and Maf and now its sorted!

Bit annoying though ain't it!

 

[Jonzy]

Check your aircon isnt randomly turning on, my ac just does what it wants.

 

[David_smith_909]

Check your aircon isnt randomly turning on, my ac just does what it wants.

same as my windows sometimes ........... i go to put it down and half way down it stops and goes back up ??

a mind of its f@kin own

 

[cuprabaz]

have a mk3 cupra T with a revo remap and a dumpvalve, sometimes when the car warms up the idleing sometimes will jump up and down from about 800 - 1150 rpm on tickover, I have replaced the coil packs recently, pluggs on last service, new lamdba sensor, all pipes and hoses appear to be connected with no visual leaks. Vag.com doesnt bring anything up. Just wondering if this is normal or there may be a small problem somewhere??

Try re-aligning the throttle body mate.

 

[jimmy2006]

just replaced the MAF sensor and its made the erratic idleing worse! anyone have any further suggestions? its got new lambda, plugs, coil packs, maf, its revo'd and runs on v power.

 

[Martyn]

Does the car run smoother (at idle) with the MAF unplugged?

 

[jimmy2006]

seems to be the same to be honest, only seems to do it when the car has warmed up and you are sat in traffic etc or pull up to a junction then the rev's become slightly erratic jumping up and down.

 

[Martyn]

Then the MAF is more than likely to be ok.

Have you changed your coolant temp sensor?

 

[jimmy2006]

no, just lambda (another new one last week) and maf (today). I havent done an ecu reset after replacing the maf (if that might help?). all hoses appear ok also.

 

[Martyn]

I very much doubt a reset would make much difference but seeing as it costs nothing it's worth a try. Disconnect the battery for 10-15 mins.

I still think it's the coolant temp sensor though.

 

[jimmy2006]

coolent temp sensor, vag com isnt showing any codes regarding a poss fault with that (not sure if it would though). what makes you think it may be that?

 

[Martyn]

Because it's a common fault with 1.8Ts which also happens to causes erratic idling

 

[jimmy2006]

yeah, just read another thread with similar problems to mine. that was the temp sensor also. will have to find out what they cost. bloody sensors!

 

[Martyn]

20 sheets max from your local dealer

 

[jimmy2006]

is it known as a coolent temp sensor or a thermostat?

 

[Martyn]

Coolant temp sensor bud. If you do a search you should find the part number no probs. The replacement should be green.

 

[jimmy2006]

thanks for your help, hope i can get this cured.