Chevrolado
Full Access Member
So with my new motor, I have been chasing idle issues since it first ran (almost 1,000 miles on the new motor).
For a while, I had a bouncing idle between 500-700rpm while cold. Then it would hesitate on acceleration. That was fixed with a AC Delco Coolant Temp Sensor.
Then it has been idling in the right place (650rpm) however, it feels like a rough idle. Like the cam is real thumpy. So much so that when people ride in the Tahoe and we're sitting at a light they are like, "is this running the way it should? Feels rough.."
Last night, I had the second occurrence of a super high idle at cold startup. On a normal basis, I will start the truck and it will rise up to about 1,000rpm and then sit at about 800-900 while it warms up. Slowly lowering until it has heat in the motor, sitting at 650. Last night, I started it and it shot up to 2,000rpm and sat there at high idle. I let it sit like that for about 1 minute to see if it will come down and it didn't. So I'd throttle it a little to try and get it to kick down (as if there was a choke on it). It wouldn't go lower than 2k. So then once operating temp started rising and it was no longer "cold" I killed the engine, let it sit for about 30 seconds, then started it back up. It went to its normal place of 1,000 and then slowly lowered back to 800 while warming up.
Then driving home I was sitting at a light and it starts bouncing again. Sits at 650, then drops down to 500ish, stumbles, then jumps back to about 750, then drops to 500, up to 700.. Keeps bouncing.
I drove through it.. parked it for the night. Came out this morning to drive to work; starts at 1k.. slowly lowers until warmed up and idling (rough) at 650 like normal. No bounce.
What is up with this thing? It's like it goes through "moods" or something. It feels rough. It idles at normal place on RPM but doesn't necessarily FEEL right. Occasional high idle at cold start. Bouncing idle while warm (sometimes).
It's all over the place and its driving me bonkers.
Any help would be fantastic. Thanks y'all!
Motor specs:
95 Tahoe - 5.7L 350 TBI with Edelbrock Performer heads, Performer TBI manifold, Performer-Plus Cam, Edelbrock piggyback ECM chip, Flowtech headers, MSD wires, coil, and cap & rotor, Autolite spark plugs.
For a while, I had a bouncing idle between 500-700rpm while cold. Then it would hesitate on acceleration. That was fixed with a AC Delco Coolant Temp Sensor.
Then it has been idling in the right place (650rpm) however, it feels like a rough idle. Like the cam is real thumpy. So much so that when people ride in the Tahoe and we're sitting at a light they are like, "is this running the way it should? Feels rough.."
Last night, I had the second occurrence of a super high idle at cold startup. On a normal basis, I will start the truck and it will rise up to about 1,000rpm and then sit at about 800-900 while it warms up. Slowly lowering until it has heat in the motor, sitting at 650. Last night, I started it and it shot up to 2,000rpm and sat there at high idle. I let it sit like that for about 1 minute to see if it will come down and it didn't. So I'd throttle it a little to try and get it to kick down (as if there was a choke on it). It wouldn't go lower than 2k. So then once operating temp started rising and it was no longer "cold" I killed the engine, let it sit for about 30 seconds, then started it back up. It went to its normal place of 1,000 and then slowly lowered back to 800 while warming up.
Then driving home I was sitting at a light and it starts bouncing again. Sits at 650, then drops down to 500ish, stumbles, then jumps back to about 750, then drops to 500, up to 700.. Keeps bouncing.
I drove through it.. parked it for the night. Came out this morning to drive to work; starts at 1k.. slowly lowers until warmed up and idling (rough) at 650 like normal. No bounce.
What is up with this thing? It's like it goes through "moods" or something. It feels rough. It idles at normal place on RPM but doesn't necessarily FEEL right. Occasional high idle at cold start. Bouncing idle while warm (sometimes).
It's all over the place and its driving me bonkers.
Any help would be fantastic. Thanks y'all!
Motor specs:
95 Tahoe - 5.7L 350 TBI with Edelbrock Performer heads, Performer TBI manifold, Performer-Plus Cam, Edelbrock piggyback ECM chip, Flowtech headers, MSD wires, coil, and cap & rotor, Autolite spark plugs.
