I have already read the FAQ for this problem, but I still need help. I sold a 1986 745Ta to a friend last year and lately it has been doing something strange. At highway speed the car bucks and then the tach drops to 0 and then back to running fine. This car had a new Bosch power stage last year, but I swapped it again with a known good one. I also put in a new distributor and set all the basics. (Base timing, base idle, CO and TPS) It runs a little better, but still cuts out.

Does anybody have any ideas? Most 740 T’s have a relay that can go bad and do this, (one of the two black ones on the strut pillar) but I can’t find one on this car!?! What about a bad turbo boost limiter? Does the TPS also work in conjunction with the ignition computer and could a bad one cause this symptom?

The car does always come back from these episodes and in most cases does not even die out completely. The harder you run it the more it will do this little thing and the hotter the ambient temp more likely it will fail. Any ideas will help I want to keep my friend happy and solve this anomaly.

Thanks in advance, Jon