cover wrote: (1997 GMC 350 Engine Performance)
My GMC is cutting out under load. It occasionally misses in 3rd gear and OD but not in 2nd. It does this at around 2300 RPM, generally on a slight uphill grade. When it misses it feels like a sharp wind hit the vehicle with a momentary dip in the tach reading). It idles smoothly (dealer tuneup 5k miles ago). Any ideas? ________________________________________
Wires. Fuel Filter.
Don't jump to "emissions type devices" or anything else until you cover the basics. dahpater ________________________________________
I had a similar situation. It turned out that I was losing fuel pressure inside the fuel tank. At less than full load, all was well. Max load caused a stumble. Isolation hose between pump & delivery tube leaked by hose clamp. "syoung" _________________________________________
It's probably not the fuel delivery system because it only happens at part throttle.
It's probably not the high voltage system (wires, coil, distrib, plugs), as it doesn't happen at full throttle.
Some other possible causes:
-- Sticking IAC
-- Intermittent Igniton Module failure.
-- Trans downshifting late.
-- TCC engaging too soon under load.
Trans and TCC errors could result from erroneous load sensors such as manifold vacuum or throttle position.
Good luck.
Rodan.