Hi all,
After a few happy days with my newly acquired 1990 780 (B230FT, 160,000miles) I encountered some roughness/missing at idle, then hard starting, poor running, eventually stalling and then only running for a few moments after starting - within a span of 2 days & less than 50 miles. Tried fuel pump relay, no change. Fuel diagnostic codes 121 & 232, so I tried unplugging AMM & it would start & idle, somewhat driveable (as much as limp-home mode ever is). So, I replaced AMM with a rebuilt unit by ProgRama, seemed like a good idea as it comes with a 3-yr warranty & 1/3 the dealer price. Car ran great for about 45 minutes - this was progress! Then I stopped the car, got a coffee, and 5 minutes later it wouldn't start. Cranked about 10-15 seconds but no sign of life. Tried again a minute later, started but rough idle, missing, etc, but got underway & it ran fine intermittently. Crappy idle persisted though, stalling out etc, until I tried unplugging the AMM again - and then it idled okay. Has anyone had experience with ProgRama's products? Does this sound like a faulty rebuild? Could the ECU have somehow fried the AMM? It's about -18degrees(C) this evening so I doubt that even if the air box thermostat were sticking the AMM would have overheated in 45 minutes of gentle driving.
Or am I on the wrong track here? Tomorrow evening's project will be tracing & cleaning all grounds & connectors but I don't believe that's the cause as it seems okay w/AMM unplugged. BTW, tach doesn't jump around so based on that I figure it's fuel system, not ignition or crank sensor... Any advice appreciated! Thanks!

Chris M,Dartmouth NS Canada,
90 780 (B230FT), 84 244 (B21FT), 83 245DL (B21A), 71 Mercedes 280SE (2.8 I-6,FI)

I'm no help here, but my 1990 240 is doing the same thing. I already tried a working AMM, a working fuel pump relay, and replacing the Crank sensor. No improvement. Time to bring it in to an expert.

Good luck.

The ground wire for the AMM is located under the intake and plugs into the block. I had a corrosion problem at the plug. Also the IAC is connected to the AMM and uses the same ground.
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1965 Mustang A block 4 speed, 1969 Cougar Eliminator, 1990 Super-Charged Thunderbird and a car (740) that my wife can drive!!!

It sounds like your crank position sensor.
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90 744ti, Airbox, K/N, Cold air, G-Valve, Dual boost control, VDO, Modified exhaust. 88 745 gle.

I don't know - if it was the crank sensor wouldn't it cause problems regardless of the AMM being plugged in or not? As it stands now it'll idle fine with the AMM unplugged. When I tried driving it today it worked fine for 5 minutes, then bogged down & began missing, then fine for a few minutes, and then stopped dead. Restarted fine but idle surging & then it was fine when AMM unplugged. No codes set this time. Started checking grounds & wiring but haven't found anything amiss so far...

Chris M, Dartmouth NS Canada