VR6 - Irratic idling from cold + couple of q's

[marty_abs 0]

Hi guys.

 

My VR6 has been idling from start ver poorly recently, going from 1k rpm down to 100 and back up again, as soon as it get hot it is fine, if i then stop the car go back to it in an hour it is also fine as it is still warm. I have read some of the other threads on here and cleaned and infact changed my isv + surrounding pipework. I havent yet plugged it into a vag-com but i hope to next sunday at a local vw meet. Anyhow as it is a problem from cold i can only assume its a thermostat or thermistor related problem, i routed around the vr6 engine book i have and some other online literature to see what stats the engine has (working on the idea i would just replace them all). Then i noticed a thermostat without a plug going into it, but no free plug anywhere on the wiring loom. Any ideas?

 

Had more of a look around and noticed this chap. No idea what it is mean to do as it has nothing inside it, and there are no male pins for the female pins to plug into. Again any ideas on the purpose of this?

 

Could it be that this plug is infact meant to go on the thermostat in the first picture and has infact been taken to the wrong place in the past?

 

thanks,

Martin

[muppetlab 0]

I think its supposed to go to the blank plug, mine did. On later models i think they have some sort of valve to vent the oil vapour but mine did not. The sensor on the other side probably should have a wire to it. Is it a camshaft sensor or knock sensor??

[Serial 0]

The socket on the engine with nothing plugged into it is the intake air temperature sensor, and it should have a wire plugged into it -- if I recall correctly the wire exits the loom at roughly the same point as the wires from the two water temp sensors in the thermostat housing, and the plug is a right-angled type. Can't remember what colours the wires are though right now.

 

The blank socket on the breather pipe is the same on my VR6 and there is also a wire plugged into that -- no idea what it's for though!

 

HTH

[marty_abs 0]

Thanks for your replys. Any chance you could have a look at your engine and tell me what teh colour of the wires are that come out of that air intake sensor?

[macas32 0]

the air intake temp sensor with the plug missing will be hanging down the front of the engine i would bet as it has a long wire but it could be plugged into the black temp sensor as its the same config plus as mine was but mine were just mixed up so both plugs were there? the wires should be blue and brown/green if its the same as my corrado.

 

by the way it sounds like the airflow meter is dodgy by the idleing prob jiggle the plug on it to see if it makes any difference and take it off and check the connections if all ok its prob knackered.

[Serial 0]

The wire colours on mine are blue/green and brown/grey. I had the same problem as macas32, the coolant temp sensor and IAT sensor plugs were mixed up, but it didn't seem to be causing me any problems... I only noticed when I plugged into VAG-COM. Much better that they're in the right way round though! :)

[marty_abs 0]

Had a thorough search, traced all wiring back to their plugs and i have no free wire not plugged in anywhere. Is this stat live on all vr's? Mines an early vr6 OBD1 engine. Could this just be an un-used stat?

 

Cheers,

Martin

[VW_OwneR_85 1]

Had a thorough search, traced all wiring back to their plugs and i have no free wire not plugged in anywhere. Is this stat live on all vr's? Mines an early vr6 OBD1 engine. Could this just be an un-used stat?

 

Cheers,

Martin

 

hello m8, in regards to the wires, i have a random yellow and black wire in that loom that looks like its been burnt off, possibly due to engine heat? did you have a yellow and black wire in your loom? if so whats it for? cheers.

[science 0]

In the first picture it looks like the inlet manifold air temperature (IAT) plug is wrongly connected to the black water temperature sender. I made this mistake during my engine rebuild, it seems like the logical connection but it's not.

 

The IAT sender should be connected to a black plug with Blue/Green stripe and Brown wires which spurs out of the loom next to the Yellow and Blue water temperature sender plugs.

 

The Black temperature sender should be connected to a black plug with Black/white strip and Black Yellow stripe wires which spurs out of the loom neat the main radiator fan plug.

If it's not there, it may be hanging around the gearbox unless the fan has eaten it.

 

The second and third pictures are for the PCV valve, not fitted, not a problem.

 

If you still have problems with fluctuating idle from cold try cleaning the MAF and TPS terminal/plugs with switch cleaner.

My revs would rise and fall for 10-30 seconds on start up. I think it was the throttle position sender, but I cleaned both and its sorted.