sly_alex

Hello all and happy new year, i'm from france so my english is not very good...

My car has a little problem, only when i'm on full boost (between 1.3 and 2 bar of boost), there are cloud of black smoke at the exhaust.

The car runs good, i have a rebuild cylinder head (500 km), i check the temperature sensor (blue plug), the throttle position sensor, the AFM...

The only thing that as not the good value is the knoking sensor, which is like an open circuit. What is the good value for it. If it is broken, i would have the boost at 1.3 bar max and i've 2 bar...

If you have an idea...

Thanks

PorscheDoc

You can try the FPR, sometimes that will cause it to burn rich

hosrom_951

Yeah, sounds like your running rich underboost (too much fuel)..........

dhallilama

Just do what i do: Pretend you're James Bond, and it's your smoke screen

really... it does go a long way to make me feel better about my over rich condition. ok, the car's... wish I was over rich...

sly_alex

What is FPR ?

jimbo1111

You may have a vac or intake leak. Losing metered air will cause the engine to run rich.

sly_alex

I will check this !

sly_alex

What does it mean FPR ?

I don't understand, please help me to translate

special tool

fuel pressure regulator

hosrom_951

From Clarks Garage, the one circled on read the the fuel pressure regulator, the one infront of it is the fuel pressure damper:

sly_alex

Thanks, so i've check the fpr in first but it's ok.

I check for vac or intake leak and there is no leak

chilibluepepper

Make sure you check all intake hoses, clamps, and hard pipes carefully. I had a similar black smoke problem which I couldn't figure out until I took my engine apart for an unrelated rebuild. Turns out one of the 3 hard pipes under the intake manifold had a leak. It would have been very difficult to visually diagnose this one. Good luck

special tool

What method did you use to determine proper function?

sly_alex

Y put all the system under presure and I listen to for leak, but ther no sound and no leak...

sly_alex

Little news, I've not enought time for my car :-(

My O2 sensor is broken the signal is beetween 45 and 50 mV instead of arround 500 mV...

But the motronic give 450 mV on the wire which go to the O2 sensor (that explain why i was thinking my O2 sensor was good), is this normal or is it the reson of the O2 sensor breakdown ?

Thanks all for your help