My 87 GMC Jimmy runs bad after it warms up..

[John87]

I have an 87 GMC Jimmy.It has a rebuilt 355 with 1100 miles on motor.After it warms up it starts to run bad.The engine light comes on and when you check the codes if flashes 41 and 42.When i looked the codes up on internet it said 1 was the Electronic Spark Control Module and the other the Knock Sensor.When the engine light comes on it starts acting up. You can't get it above 35 MPH and if you try to press gas pedal down it's like there's no power.It wont speed up...You don't hear engine RPMs come up...nothing. If you continue to keep pressing gas pedal further down the only thing that happens is you start to feel it sputter and eventually you will here a pop come out the exhaust . Taking off from a dead stop is almost impossible.I have also been told it could be something in the distributor.When the engine was rebuilt the distributor wasn't replaced. Any help will be greatly appreciated.

 

[clandr1]

Sounds like it could be a timing problem (and possibly distributor-induced)? I'm sure someone will be along with better advice soon.

eta: maybe temp sensor is bad? Could be telling the computer that the engine is still cold, causing it to throw knock & timing codes? Could be a quick (and cheap) try before getting into anything more complicated.

 

[John87]

Thanks Chris.I'll have to check into that.It's driving me nuts not being able to drive it.Have done alot of work to it fixing it up.

 

[496truck]

I have an 87 GMC Jimmy.It has a rebuilt 355 with 1100 miles on motor.After it warms up it starts to run bad.The engine light comes on and when you check the codes if flashes 41 and 42.When i looked the codes up on internet it said 1 was the Electronic Spark Control Module and the other the Knock Sensor.When the engine light comes on it starts acting up. You can't get it above 35 MPH and if you try to press gas pedal down it's like there's no power.It wont speed up...You don't hear engine RPMs come up...nothing. If you continue to keep pressing gas pedal further down the only thing that happens is you start to feel it sputter and eventually you will here a pop come out the exhaust . Taking off from a dead stop is almost impossible.I have also been told it could be something in the distributor.When the engine was rebuilt the distributor wasn't replaced. Any help will be greatly appreciated.

I would start there. It is in the distributor. Known to fail when hot.

 

[John87]

Thanks for the help Brian.. That was one of the parts that was reused when i had the engine rebuilt.I sure hope that's it.
John