HomerSimpson

3.0L Vulcan, runs normal otherwise.
When pulling slight grade engine cuts out when it would normally upshift to 3rd gear at 35-40 mph (approx 3200 rpm) the power cuts out momentarily. Sometimes it cuts out 2-3 times. Then it runs normally up to freeway speed.

Doesn't happen if I accelerate very slowly, or on level terrain. There is no indication of transmission slipping, rpm does not increase.

Took it to very reliable mechanic. He monitored inputs with his diagnostic system. He tells me that everything seems normal and then various sensors report "no data" momentarily, then returns to normal. Sensors he observed were throttle position sensor, crank position sensor, fuel pressure sensor, etc. He tells me his guess would be a bad ECM, but he is not certain.

We've checked the ECM ground and it seems intact and ohms out properly.


Anyone have any ideas?

chipset

Without seeing the car and what you have said i'm GUESSING that when the engine moves on it's mounts upon acceleration A circuit opens in the harness shutting down power to the " no data " sensors. Look for an opening or a cut wire in that area that feeds those sensors. A bad ECM ????. Your mechanic will have to put his scanner on it and do a live data stream on a test drive. If he has a $3000.00 scanner there will be no problem. Those are the scanners that can lock and unlock your doors and roll up and down your windows. Good luck