850 Who's willing??

[michael98632]

This is what I'm up against. I have a 95 850 turbo auto. I'm trying to diagnose performance issues. When the engine is cool or cold it will obtain full boost and feel very lively. How ever once the temp gauge climbs to the "normal" operating temp it feels a lot less spirited and won't pull but 2 or 3 psi of boost. The waste gate actuator works. I've seen the rod moving. Ide taken to the dealer and they said to me that my pcv system is plugged and that could be causing the low boost issue. No its not after changing the system with new parts I saw no change. Any serious help or advice would be appreciated

 

[bricksquad]

free bump just because i want to know what this could be

 

[bricksquad]

just did some research for you,try disconnecting the line that goes to your turbo control valve after it starts acting up. if boost goes back to normal it might be that. just dont push it while its disconnected or youre gonna hit fuel cut off.

 

[michael98632]

What one? There are three vac lines on it.. am I right?

 

[doucheNozzle]

Why are you doing full boost while your engine is cold?

 

[Jack]

Tcv possibly

 

[bricksquad]

the one going to your turbo from the tcv? i think. someone chime in...

 

[michael98632]

What I said was it can....not that I'm doing it.

 

[doucheNozzle]

What I said was it can....not that I'm doing it.

Well if you know it can do it...

But seriously, I feel like this thread is just a duplicate of another thread of yours which is a duplicate of another thread.

 

[Janspeed]

Cold engine = coldstart mixture = normal performance.
seems to me the engine is not getting enough fuel when warm.
did you check error codes? any emissions related?
how is the fuel delivery? enough pressure? enough flow? fuel pressure regulator OK? vacume hose to FPR OK? properly connected?
fuel filter clogged up?

 

[michael98632]

Jenspeed. No I haven't seen any check codes coming up at all. It does seem to have this odd sort of surge almost a 50rpm change up and down at times under load. Is this a fuel related thing?

 

[Janspeed]

i don't know to be honnest.
why not start by checking the basics in post #10?

another thing you might want to check is the CBV (it is behind the chrome cover on the compressor side of the mitsubishi 15G turbo) take the cover off and inspect the membrane, it should not have any tears in them)
A torn CBV will prevent the turbo from making boost but the air will stay in the system so no error codes will pop up.

The TCV (turbo control valve) was already mentioned, check if it works by hooking it up to 12V while blowing air through it. Make sure all hoses to the TCV are connected correctly and not leaking.