We recently changed the engine on my 86 740 turbo and ported the head and intake manifold. We changed timing belt, spark plugs and the engine comes from a 1989 760 turbo, which i drove for 7 hours on the way here. After the swap we got it to start, but ran rough and no power over 4-5 psi of boost. we found out its a gas problem.
the car seems to flood itself when its hot, like it believes its still cold and shoots way too much gas. after its hot, you cant start it unless you unplug all 4 injectors and then she fires up for 1-2 seconds, enough to burn the extra gas and you have to replug the injectors as soon as she fires up. also, the engine smokes alot, and after revving and driving it just almost stops smoking. any ideas??? need help!

 

Fuel issue might be a coolant temp sensor issue.

Where is it smoking, and did you apply any anti seize to exhaust bolts or spill something during the sway?

Wait for the experts to get on.

 

im wondering if it would be the wrong computer for the engine or the wrong air flow meter

 

You need a 541 or 591 ecu. The amm should be a 007. Both cars are LH2.2 so the computers/amm's should be the same. As mentioned above, the ecs will make the car think its like 40 below zero and flood. What you're saying is when it starts cold, in closed loop, it's fine. Then when it gets warmed up and goes into open loop, it runs pig rich. Do yourself a favor, avoid a bunch of head scratching and check the voltage on the O2 sensor. I'd wager a dollar that it's toast.

 

the ecu is 541, the amm is 007 on the donor 760, i didnt check the numbers on the running car, cause its about 100 kilometers from here, at my uncles garage. i dont believe he has a voltalge meter, but we unplugged the o2 sensor and it didnt do a difference. ill bring the o2 sensor from the donor 760 and the ecu and the amm. also, are the injectors continuous flow or are they each timed? each time wed switch them around, it didnt seem to do a difference

 

The injectors batch fire...all at once. There's a good chance both O2's maybe no good. They are often overlooked but are the only sensor that tells the ecu how it's doing. The AMM, the ecs, the tps all tell the ecu how much fuel they want...the O2 tells the computer if they are lieing!!