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In Reply to: Intermitent poor performance--any ideas? posted by Jim Derrig on January 14, 2001 at 16:08:33:
1. vibration, though not extreme
2. low power, can barely move the car
3. (a) idle won't hold and the engine stalls OR (b) the idle holds at about 4 hundred rpm and the engine clearly struggles to keep running
4. if I turn off the ignition and restart the car, it fires up just like nothing ever happened and it runs fine.
The most perplexing thing is that despite the dual DME and other dual systems it DOESN'T seem like the problem is confined to one side of the motor. If one side was cutting out, that would explain the slight vibration and low power, but not the inability to hold idle or the stalling of the entire engine, right?
The fuel lines have been cleaned with compressed air, so nothing is plugged. Also, I recently replaced both fuel pressure regulators to solve a different problem. The current problem existed before and after the replacement.
The car passed an emissions test just a couple days ago, with flying colors.
The ECU does not show any fault codes.
I'm stumped, anyone out there know what the problem is?
I can't add much to what is suggested on other responses to your post. However, my 750, although runs perfectly on all 12 cylinders, will not run/hold idle on cylinder bank 7-12 alone. On bank 1-6 it will idle smoothly by itself. My point is that one of your banks is shutting down for some reason. I suggest you check fuel pressure/pump, coil, coil high tension lead (to distributor), crank position sensor. ALL items can be checked by switching positions to see if the problem changes side...that is if you know what side is causing your problem. You can also switch positions of all relays and DME's. If you are not getting an EML light, then the problem is probably something other than the EML system.