rs2 cold start trouble

[bout1977]

hi ,
first, i apologize for my poor english ;-)
here is my problem :
since a few weeks , at cold start , my engine tumble ant stops , and when i WOT it stays at low revs , and some exhaust and intake explosions occur .....
at iddle it seems to run on 4 cylinders ..
and after a few time (5 minutes) it sudenly run fine.
the are 5 new plugs on it .

thanks for your help

[Greg_S]

Has it been sat for a long time? Any signs of damp in connectors and sensors? Have you pulled fault codes?

[bout1977]

i' haven't a diag system .
The car is runing every week or starting at least every month on cold season

[newsh]

Check the wiring plug to the white sensor on the back of the cylinder head. The ECU uses this sensor for coolant temp. Maybe it gives a false reading during warm up.

[4WDrifter]

I had similar symptoms with my S2 ABY and it turned out to be this.

[bout1977]

the wiring seems to be ok , so i disconnect the sensor , and it runs fine....
So , is this critical to run without this, sensor , while i will found a new one ?

[bout1977]

thanks for the help guys !!!

[UrS4boy]

I offer you the following:

Missing and Hesitation diagnostics:

http://forums.quattroworld.com/s4s6/msgs/22611.phtml

Power Output Stage Diagnostics:

http://forums.quattroworld.com/s4s6/msgs/153152.phtml

G62 Coolant Temp Sender used by the ECU to control fuelling:

http://forums.quattroworld.com/s4s6/msgs/20985.phtml

[ristokru]

I dont want to make new topic. My car makes also same but has 3B engine. What sensor it can be. If engine is gold then rpm goes between 400-1000rpm. About a minute it will be steady.
What would be normal rpm with cold engine? Mines always been 800rpm. Cold or warm.
Also RPM-s will go crasy if i will stop before stop sine and then it will also do like it was gold engine. But after 20 minutes of ride, everything goes ok.

[Greg_S]

Check out your idle stabilizer valve to make sure it’s moving freely. You can run output tests with a simple blink code lead yourself. If not check the temp sensors as listed above

[ristokru]

Check out your idle stabilizer valve to make sure it’s moving freely. You can run output tests with a simple blink code lead yourself. If not check the temp sensors as listed above

Does those things you mentioned also make engine stutter? I today started car and it looks like only 3-4 cylinders work. revs jumped 300-1000rpm. After 10 minutes of ride and car was perfect again.

[bout1977]

finaly that wasn't the temp sensor ... i disconnect the blue connector on the bipass on the oil gaz recirculating circuit ... this is located near the ECU temp sensor ...

[ristokru]

Does those things you mentioned also make engine stutter? I today started car and it looks like only 3-4 cylinders work. revs jumped 300-1000rpm. After 10 minutes of ride and car was perfect again.

Anyone?

[bout1977]

this symptoms are nearly the same as mine, disconnect the blue connector on the oil vapor recyrculating circuit, under the throtle bodie .
just for test , if its this your engine may run fine just when you disconnect this

[ristokru]

this symptoms are nearly the same as mine, disconnect the blue connector on the oil vapor recyrculating circuit, under the throtle bodie .
just for test , if its this your engine may run fine just when you disconnect this

I have 3B engine. Its little different.