Running rough when the engine warms up.

[m1000snopro]

Hey guys I have been trying to figure out the problem, when i start the truck and drive it, it runs great. once it gets up to temp it start running rough and hesitant. i don't think this has much to do with it but recently the temp gauge just started climbing all the way to the max hot side. I put it on a scanner twice now it and it is not actually that hot. is there something that would cause this? thanks

 

[Chevyguy]

Hey guys I have been trying to figure out the problem, when i start the truck and drive it, it runs great. once it gets up to temp it start running rough and hesitant. i don't think this has much to do with it but recently the temp gauge just started climbing all the way to the max hot side. I put it on a scanner twice now it and it is not actually that hot. is there something that would cause this? thanks

What temp is the Coolant Temp Sensor reading. TBI motor?.

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[m1000snopro]

yes TBI motor, when we hooked the scanner to it was reading 185° the second time it was 187°.

 

[Chevyguy]

yes TBI motor, when we hooked the scanner to it was reading 185° the second time it was 187°.

That's a little low. You should be closer to 195 degree's. Mine run's between 190 and 195. Do you have a 195 degree thermostat installed in your engine?. That's what it require's.

Clayton

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[m1000snopro]

i will go grab one and rule that out cause i am not sure. thanks man

 

[gmbellew]

It also could be a vacuum leak.

 

[Durfman77]

i will go grab one and rule that out cause i am not sure. thanks man

Been working on my truck for ten months now somewhat different than yours but along same lines,,,, Did the fuel pump---All sending units for Temps---TBI rebuilt----Idle control replaced--New distributor & plugs and ICM----BUT got to thinking about timing so put timing light on engine while was running Ruff and timing was All over the place????----So got another ICM and WOW!! Ran perfect and timing stayed perfect,, Thats what it was all along with me,,,--------------My truck ran bad when started then after few minutes was ok so might not be it BUT would check out timing???

 

[Chevyguy]

Been working on my truck for ten months now somewhat different than yours but along same lines,,,, Did the fuel pump---All sending units for Temps---TBI rebuilt----Idle control replaced--New distributor & plugs and ICM----BUT got to thinking about timing so put timing light on engine while was running Ruff and timing was All over the place????----So got another ICM and WOW!! Ran perfect and timing stayed perfect,, Thats what it was all along with me,,,--------------My truck ran bad when started then after few minutes was ok so might not be it BUT would check out timing???

Did you set your's to 0 degree's?. TBI motors need to be set to 0 degree's at base idle. Alway's carry a spare ICM in your truck.

Clayton

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[Durfman77]

Did you set your's to 0 degree's?. TBI motors need to be set to 0 degree's at base idle. Alway's carry a spare ICM in your truck.

Clayton

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Yes I set at zero---Can,t believe how the timing light bounce all over then like snap back in place,,,,

 

[m1000snopro]

i actually had an ICM go out about 3 months ago and i replaced that. but thank you for the idea and i place to check. i will look into timing, it has been quite awhile since i have checked it.