VR6 won't idle when cold, tried VAG-COM nothing obvious

[Rpmayne 0]

Hi, I've been having trouble with the VR6 idling since running after being stored for a year.

 

Originally would start but idle very rough hot or cold.

 

Checking the ISV and it was stuck. Cleaned it and got it moving but this then meant it wouldn't idle at all when cold.

 

Bought a second hand ISV, same problem.

 

Plugged into VAG-COM, no errors.

 

TPS goes from about 12-93 degrees, coolant temp appears to be correct.

 

Only change I can see is when I unplug the TPS, it hunts then instead of stalling. Plugging it back in when running makes it stall instantly.

 

Any ideas?

 

I did have an odd experience recently where I went round a roundabout quickly, and on the way out the revs dropped to idle yet I was pushing the accelerator. Pulled over, turned throttle manually and the revs picked up, got in and it was fine again...? Maybe / maybe not related.

[fendervg 33]

Inlet vacuum pressure leak? Check the inlet rubber boot for cracks and all the hoses for tight connections and leaks. You can also do a vacuum pressure test with a cheap gauge and some hose and a t-piece connector.

[John Blount 11]

As above more than likely an air leak, could also be the blue temp sender if it only does it when cold.

 

I had a simalar thing happen to me and as you say it's been sitting for a while it might be worth changing the oil if you haven't already? Mine did the same where it wouldn't idle properly and it was because the oil pump was faulty and it was jamming the lifters open, once the oil was warm they would work fine and the problem went away. Changing the oil and possibly cleaning the throttle body might sort it.

[ozone 10]

I don't know whether this would be a hindrance or help, but I stored my vr6 for about a year and found similar symptoms when starting from cold, erratic idling etc. I checked the usual suspects and as I was checking my breather hoses I found a cracked PCV value. Once I replaced the PCV it was cured.

[Rpmayne 0]

I've managed to source a PCV (mine does look oily and not in good shape) which should be turning up next week, checking the pipes though and the T-pipe which connects to the PCV is spongy and cracked so was looking into replacing that. Not having much joy, tried VW and they're struggling to find the part on their system. Anyone else found a replacement, Samco etc? I bought a silicon hose kit and fitted a few years ago but pretty sure it didn't include this.

 

Also heard the fuel pressure regulator can cause problems (pretty sure its running rich, plugs are black soot, not oily) and looking for one of them as well.

[fendervg 33]

The FPR is a standard part from Bosch/VDO and is easily available from VW or aftermarket and not expensive.