1990 10vt avant - falls on its face at 4k rpm

[Bares, Vittorio]

Hi - I've been chasing this for some time...

 

Have a chip and 1.8bar wastegate spring, with recirc valve.

 

Boost gets to 1.8 (according to dash computer), sometimes over-boosts to
2.0 (and usually cuts out completely there).

 

Changed in the past 6months or so:

*       Plugs/wires

*       Rotor/Cap

*       Injectors

*       TPS 

*       Fuel Filter

*       Fuel Pump

 

Symptoms:

*       slightly lumpy power getting to 4k rpms - but once there, motor
just falls on its face and won't get any higher.

*       Lumpy power can be smoothed out if you keep the gas pedal at mid
range - but again, falls flat around 4k (although sometimes it will be
ok to a little more than that.

*       When the car is cold, it will run to about 5k-5.5k without
bogging - power is also much smoother.

*       Temp gauge is pretty consistent and looks accurate.

*       Warm weather, its all much worse - winter weather is better, but
still not good.

 

Possibly multi-function temp sensor?

 

I'm figuring this is not a boost leak since I'm getting plenty of boost
- however, I think the over boost is an indication of something else
going wrong?

 

Could it be the coil going bad at high RPM?

 

Pretty miffed at this point on how to get to the bottom of the issue.

 

Vittorio -