blue_tractor_man
Member
To keep this tractor related, this is the vehicle I use to pull my 1964 Ford 4000 4 cylinder tractor.
This vehicle is my daily driver, a 1991 Chevy Suburban with a 5.7 (350) throttle body injection with 4L60E transmission. It has the stock distributor, coil seperate, not on top of distributor cap. The TBI unit (NOS) was replaced with the rebuild several years ago. It got a new Chinese distributor with the rebuild, but with a GM module.
It has a bone stock engine, a Jasper rebuild, and with about 100,000 miles on the rebuild has developed a cold start stumble, and a very strange ongoing stumble/shudder/miss when cruising at low load. Under acceleration the motor runs perfectly. Every once in a while the motor will stumble like you cut the key off for half a second. No pattern to that.
I replaced the ignition module inside the distributor a while back with a genuine GM module. No change. I replaced the O2 sensor. No change. I removed, checked, and replaced the EGR valve. No change.
I am leaning toward thinking it is some sort of weird vacuum leak that is jacking with the computer.
Ant ideas? What do I check next?
This vehicle is my daily driver, a 1991 Chevy Suburban with a 5.7 (350) throttle body injection with 4L60E transmission. It has the stock distributor, coil seperate, not on top of distributor cap. The TBI unit (NOS) was replaced with the rebuild several years ago. It got a new Chinese distributor with the rebuild, but with a GM module.
It has a bone stock engine, a Jasper rebuild, and with about 100,000 miles on the rebuild has developed a cold start stumble, and a very strange ongoing stumble/shudder/miss when cruising at low load. Under acceleration the motor runs perfectly. Every once in a while the motor will stumble like you cut the key off for half a second. No pattern to that.
I replaced the ignition module inside the distributor a while back with a genuine GM module. No change. I replaced the O2 sensor. No change. I removed, checked, and replaced the EGR valve. No change.
I am leaning toward thinking it is some sort of weird vacuum leak that is jacking with the computer.
Ant ideas? What do I check next?