My husband told me to join a forum to try to figure out whats wrong with my truck. We're at a loss right now. Its a 90 s10 blazer 4.3 4x4 with almost 170k on it. It starts spitting and sputtering until its hot. Once its up to temp, then it runs fine. If its too cold out it does that. Anything around 50 degrees outside and its fine. Almost everything has been replaced. I have another 90 i was pulling parts off of. Swapped ecms, fpr, new plugs, wires, cap, rotor, distributor, injectors, map, coil, fuel filter, egr...i cant think of what else, but really the only thing we didnt mess with yet is the tb and actual motor. We have no idea not. It acts like it isnt getting enough fuel, but then its fine once it gets up to temp.

 

maybe the temperature sensor for the computer is bad causing the computer to not compensate for the cold weather. my 90 fullsize kinda runs funny when i first start it but nothing to bad, it start popping out the exhaust with a slight misfire, only does it like 10 times or so within the first minute and it fixes itself. someone told me it may be the oxygen sensor giving a false reading also. i been dreading replacing it cause its rotted really bad and dont want to brake it.

if you bring it in to a shop and they hook a scan tool it they may be able to look at the fuel trims and temperature that the computer is receiving and pinpoint the problem.

 

If you want to use the "paperclip method" to see if there is any DTCs in the computer, we can help ya.

Changing you coolant temp sensors is also a great idea. The one on the drivers sde head is for the dash gauge - do.t touch. The one on the intake near the thermostat housing is for your computer - swap this one from your other truck

 

Tried the temp sensor. Didnt do anything. Swapped/replaced every sensor except the O2. Took apart the tb and it was fine. Adjusted the timing again, still acting up. It has a miss now too, the plugs, wires, and injectors checked out fine. The cap, rotor, and distributor are new. The miss started when this problem started. We're almost through the entire truck and completely out of ideas. It only does this when its cold. When it warms up its fine.

 

EGR valve ?

sorry see you did it