Hello all! I have had a problem with my 91 940 Turbo for over a year now and everyone I talked to said I should post it on the brickboard. This is my first post I hope you guys can help!

Symptoms: no power under 3K RPM; poor power after 3K RPM; no engine response, very slow response; will not brake-boost past 2 psi; idle fluctuation between 750-1200RPM; rough idel; engine makes loud "bog" noise from intake when throttle is opened and takes several seconds to respond, even in neutral. Does not seem to get terrible gas mileage, but could be better. Does not smoke white, blue or black.

Things checked/replaced: NEW coolant temp sensor, o2 sensor, knock sensor, crank position sensor, TPS (installed by 2 different Volvo mechanics), idle air control motor, plug wires, plugs, cap and rotor, fuel filter, fuel pressure regulator, air filter, harmonic balancer, lower timing gear, timing belt, tensioner, intercooler, torque converter, and catalytic converter. Cam timing is dead on, IGN timing is 12D BTDC on idle; compression is exactly 150 psi for each cylinder (short block recently replaced with Volvo re-man unit – may have 15k miles by now); waste gate actuator is very tight and was swapped; there are no leaks in the intake plumbing, no unusual water/oil consumption; and no vacuum leaks I could detect in the year of investigating this problem.

Things to Note:
Total of 3 turbo set ups used (went from TD04 to 16g to Garret T3 with old style manifold) – problem was apparent in all of them; Spark plugs are white on the electrode and have black carbon around the face – the picture in the Haynes said to check for weak ignition, fuel system, and engine management. Alternator has giving me lots of trouble – second re-man alternator and barely charges above 12 when hot with A/C on - haven’t had the money to replace it AGAIN. Distributor seal leaks at the shaft, oil in cap most of the time. (makes no diffrence when cleaned out) I have not replaced the fuel or IGN computers, or the AMM. Wires for all fuel injectors have been cut and re-crimped, not soldered. AMM wires have been cut and re-soldered. (please don’t ask why...haha) Resistance values have not been check, no check engine light.

Any help would be greatly appreciated; I am sure this will put you guys to the test!
Thanks for any help!!!

Chris