Revs sticking and dropping off far too quick

[Monkriss]

Basically, my car went in for an MOT the other day and it failed on Emissions. This is only because they couldnt do an accurate reading.

If you press the pedal down and keep it in one position, the revs build up and once they get to 2500 revs, they let go of the pedal slightly and the revs drop off completely, so they push pedal down until revs get to 2500 again, and they let off slightly and it drops all the way down. You cant get it to stay at 2500, no matter how hard you try..

I have tried to; cleaned the throttle body
blocked off EGR
disconnected battery, did a vag test on computer and it didnt come up with any problems on the engine other than throttle position sensor, but that was straight after refitting and it went back to normal with no problems soon after.
Fixed any points that might be letting in air.


Because it has failed MOT i cannot drive the car to have it make new learns, which i might need now it has been cleaned?
The garage says it needs a new Throttle body. But the same garage said they had cleaned the throttle body, but when i had a look at it, it was filthy, but after a clean it looked to be in good working order.

also, the TPS is giving a reading, so i dont think it is that, that is failing.

any other ideas? i dont want to get a new throttle body (£300) if i dont need one. Might it be the actual accelerator pedal? can it be cleaned or serviced?

Cheers

 

[tom w]

When they removed the tb to clean it did they re align it via vag com ? As most times they need to be

 

[Monkriss]

nahh we didnt, forgot :S. and i highly doubt the garage did, no evidence they even took it off. but as it has now been cleaned, it is still letting in the same amount of air or more. so once we tell it that it has re align'ed could that allow the revs to stay where i want them?

 

[denzil691]

Should do once it re aligned mate if not search for a boost leak

 

[Monkriss]

tried the re align.. didnt work. my revs were fine first thing this morning, but after it got warm, it went back to normal.

had a look in the throttle body, took off the MAF. when i put foot down, the throttle valve opens slighlty, and when i take my foot off the pedal, the revs drop, before the trottle closes. surely the throttle should close before the revs drop?

also, boost leak? is that just for diesels? i cant find any air leaks :/

 

[Monkriss]

yeah, got in car this first thing this morning. and got revs to 2500 fine. went back to 1000, then back up to 2500 fine again. then i drove around the block and it went back to going up by itself when i only push the pedal so hard, and drops quickly if i let off slightly.

My question is. I failed emmissions because they couldnt keep revs steady. Does the car have to be warm to do emmissions? or i could ask the garage if they could retest emmisions first thing in the morning if i leave the car there?

What are the chances it actually needs a new throttle body? i dont want to folk out loads of money for something that wont make a difference? such a stupid problem. doing my head in!!!

 

[ibizacupra]

learn to control the throttle... they are sensitive
if its faulty it will pop a fault code

 

[Monkriss]

it really isnt how i control it. it is a fault, but it isnt reading. it is as if it thinks it is working correctly.
ordered a new throttle body so will see if that fixes it...