740 only runs > 3,000 rpm Topic is solved

steveb455 · Post by **steveb455** » 25 Apr 2005, 21:06

I'm considering to purchase a nieghbor's '87 740 turbo sedan. It starts, then suddenly quits. Will do this over and over. If I pump the gas pedal and keep the rpms >3,000, it seems to run great and smooth. As it warms up after a few minutes, it will run at about 2,500 rmp, although a little rough. Any slower than that and it dies. Help???

M Jarve · Post by **M Jarve** » 26 Apr 2005, 12:50

My guess would be either low fuel pressure or bad AMM. Maybe look at the throttle position sensor too. A B230FT should idle at <1000 RPM once warmed up.

steveb455 · Post by **steveb455** » 26 Apr 2005, 21:05

Thanks M Jarve! I unplugged the MAF (same as AMM I believe) and it started and ran great, but at 2K+rpm.

If I plug the MAF back in, it starts and immediately dies. Time for a new mass air flow sensor.