1990 audi 100

I have a 1990 audi 100 that starts and idles fine while sitting. Once I take it out and drive it and it warms up and get it to 3500 rpm's it then backloads and runs poor. It will only go about 15 - 20 mph. It continually
fouls out the spark plugs. Have replaced the timing belt and reset cam timing, put on new coil, new Bosch plugs - wires - cap - rotor, new Bosch O2 sensor, cleaned throttle body, checked temperature sensing injector, checked fuel pressure hydraulic actuator, adjusted and set the CO on the car, new fuel pump, and checked many of the various switches around and on the engine. Today they are going to put an exact match ECU brain on the car to see how it responds. If it still runs poor at that point they are wondering where to turn next. Any ideas?
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ray wrote:

Have you checked to see if your ISV is stuck or if the throttle body switch that activates it is opening above closed throttle?
Check the line of fuses in the relay / fuse box that are along the side. They are sometimes mistaken for spares but are actually part of the engine management system.
I would bet that you have already checked for vacuum leaks.
Check all engine ground connections.
Auto or 5 speed?
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Yes, ISV is towards the front correct? Switch above T-body checked. Fuses checked first thing. Those one's you mentioned are there. And yes, vacuum lines checked. Thanks for the help.
TonyJ wrote:

--
ray


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Oh yeah, auto.
TonyJ wrote:

--
ray


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Not too familar with the Audi 100s, but here goes.....................
ignition coil giving a weak spark?
Coolant Temperature Sensor for the fuel injection?
How was the CO adjusted? By checking the current to the fuel pressure regulator? I think that you have the electronic fuel pressure regulator on the side of your Fuel Distributor. I have changed a few FPRs for different VWs and Audis, so yours might be causing problems.
catalytic converter or muffler clogged? What is the vacuum during different engine rpm levels?
Either too much fuel, not enough spark at the right time, or not enough air. ;-)
--
later,
dave
(One out of many daves)
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