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The 91' 740 ("the dog")runs good but the acceleration is terrible compared to another 89' 740 my daughter has and compared to another 91' 740 I have. The two with good acceleration are comparable. The two 91s are Regina systems and the 89' is a Bosch system. I just replaced the engine in "the dog" with an L-engine (the old engine #4 intake valve broke at 167K miles??) and the new L-engine runs very quiet and smooth (love those longer skirt pistons and oil squirters) but has terrible acceleration just like the old engine. Besides the engine, the AMM, Regina coil, fuel pump and filter, plugs, plug wires, rotor, cap, dist. seals replaced, and other things I haven't probably mentioned have been replaced over the years (I have owned the car for 7.5 years) but there has been no change in the poor acceleration. The L-engine has 88K miles on it and is in great shape (I could see the crosshatch in the cylinder walls when I removed the head and had it milled and the oil seals/hushers replaced). The three sensors in the head are different since the head is different and of course the sensors in the block are different.
The engine timing almost seems to not have enough advance. I checked it with a timing light and it idled at about 12 degrees BTDC and did advance when the throttle pulley was turned. Were there some e-proms that gave really bad acceleration? If so, where can I get replacements and what is the number on the e-proms that give better acceleration. I have a 90' 740 my daughter wrecked and which I still have for parts with the Regina system. I may try replacing the ECU from this car(are the e-proms in the ECU by the passenger right foot and how many stickes are there?)if someone thinks that is a good idea. I can't remember what the acceleration was like in the wrecked car for sure but I think it was better.
Any ideas would be appreciated.
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