Idling Issue Revs Drop Help Please

[Grande GTi 11]

Hi all 

I am after some advice as my 94 VR6 ABV is having issues on revs a idle.

Basically it started a few months back initially when driving for a short while, when coming to stationary from any speed 50/60mph or 5/10mph the car would switch off completely, if you turn the key it would start up straight away, However its slowly getting worse, it also started to rev up on its own, which a new IDLE control valve solved that issue but the cutting out it hasn't, It also seems like its over fuelling. Also Now if you rev it to 2000 or more on its way down it will cut out again.

So far I have changed the Idle control Valve and also the Vacuum pipe on top of the Throttle body to Vacuum Valve.

Has anyone had this issue before and any ideas on how to put it right 

Thanks 
Ricky

[fendervg 33]

It's pretty common, and unfortunately can be hard to diagnose - a search on here for VR6 idle and cut out will give you plenty of food for thought.

Have you had the car scanned? This would be my first step.

Next would be the PCV valve and hose between the rocker cover and the air inlet elbow - check, clean or replace. Also a back square baffle box on the right of the rocker cover near the auxiliary water pump. There is also a mess of vac tubing behind the airbox for the activated carbon canister etc.

Then you have things like the hall sender near the coil pack or on the distributor, MAF, etc., but a scan for fault codes would help with these.

[blue95 0]

get the car scanned first, if you cant wait check wiring, my idle control valve wiring was shot so casued me similar issues

Edited November 15, 2020 by blue95

[mnmv12 2]

When I  bought my  car in the summer it had this fault and it was a nightmare to drive. Nothing like rolling onto a busy roundabout and losing your engine and steering plus it started to kangaroo up the road under acceleration. After doing numerous scans checking all the intake pipework and throttle body dash pot and replacing various ignition components the fault persisted. I was convinced it was the maf despite the voltage readings being in tolerance. After fitting a new JP maf i still had the problem and after reading on here about problems with after market maf sensors i then purchased a genuine bosch sensor. Problem solved!😀

I would also check first that you have a good voltage at the battery (over 13v) when the engine is running. A dodgy charging circuit  causing low voltage can cause all sorts of weird faults.

[Keyo 47]

3 hours ago, mnmv12 said:

When I  bought my  car in the summer it had this fault and it was a nightmare to drive. Nothing like rolling onto a busy roundabout and losing your engine and steering plus it started to kangaroo up the road under acceleration. After doing numerous scans checking all the intake pipework and throttle body dash pot and replacing various ignition components the fault persisted. I was convinced it was the maf despite the voltage readings being in tolerance. After fitting a new JP maf i still had the problem and after reading on here about problems with after market maf sensors i then purchased a genuine bosch sensor. Problem solved!😀

I would also check first that you have a good voltage at the battery (over 13v) when the engine is running. A dodgy charging circuit  causing low voltage can cause all sorts of weird faults.

Ah yes them JP mafs need torching- had my fuel injectors refurbished + new Bosch FPR+ new VDO fuel pump and sender fitted only to find out it was that crap JP MAF sensor- lesson learnt.   

[Grande GTi 11]

thank you all for the support so far

 

seem to be making some steps in putting this right, As said i replaced the ISV the other month, so i thought that was that and with the car still doing the same thing, its why i drove me to think theres more to it, so replaced the throttle position sensor, new vacuum pipe off the breather and cleaned out throttle body, and that made it worse today.

We scratched our heads in disgust as the idling had got worse instead of better, turns out after everything the replacement ISV was shot too.

Fitted the old one back and the revs held at 900 as supposed to 1500 so with that said now thankfully we may have this problem under control

[fla 9]

test the isv by pulsing it with 12v.  You should see the flap open fully and then close without getting stuck.  Give it a light mist of oil to keep it moving freely.  

[Grande GTi 11]

thanks mate I will check this, this weekend, but thankfully I have managed to locate one off Chris Ferry which should be with me in a few days, so will give it a good through clean and then lightly oil.