3vze rough idle when cold.

[ballinjefe22]

91 pickup 3vze. I tried to do some searching all over, but I cant seem to find someone with the same issue. I read about a lot of cold starting/hard starting issues, but i have never had a problem with that at all...it always starts up within about 1 second of the key turning over. Issue started after i put in some new valve cover gaskets and a new plenum gasket. I reinstalled everything per the haynes i have, and then got all the vac. lines back on according to a FSM that i found online. When I start the truck cold, the idle runs at about 800-1000, which it did before, but the idle is very rough and if i try to drive it it has very little power and misses like a B If i just let it sit there and idle for a few minutes (5-15) it goes back to normal and runs like a champ. it doesnt gradually get better-it just magically idles and runs fine. I removed the connector to the CSI and it didnt change anything..how can i check if its actually sending power to the injector? how long does the injector run when started up cold? I start it in the morning, and after it gets better, it will be fine sitting in the lot at work for 8+ hours, it seems to only be an issue after sitting over night for about 10ish hours. Any ideas, guy? thanks in advance. Please feel free to link me to any previous posts that i may have missed.

 

[trapper 1983]

91 pickup 3vze. I tried to do some searching all over, but I cant seem to find someone with the same issue. I read about a lot of cold starting/hard starting issues, but i have never had a problem with that at all...it always starts up within about 1 second of the key turning over. Issue started after i put in some new valve cover gaskets and a new plenum gasket. I reinstalled everything per the haynes i have, and then got all the vac. lines back on according to a FSM that i found online. When I start the truck cold, the idle runs at about 800-1000, which it did before, but the idle is very rough and if i try to drive it it has very little power and misses like a B If i just let it sit there and idle for a few minutes (5-15) it goes back to normal and runs like a champ. it doesnt gradually get better-it just magically idles and runs fine. I removed the connector to the CSI and it didnt change anything..how can i check if its actually sending power to the injector? how long does the injector run when started up cold? I start it in the morning, and after it gets better, it will be fine sitting in the lot at work for 8+ hours, it seems to only be an issue after sitting over night for about 10ish hours. Any ideas, guy? thanks in advance. Please feel free to link me to any previous posts that i may have missed.

 

[trapper 1983]

Hey bud did you ever find out what your problem was? I have a 94 t100 3vze that's doing the exact same thing. I've put alot of new parts on and nothing. Hoping you could help, would highly appreciated

 

[trashguy]

91 pickup 3vze. I tried to do some searching all over, but I cant seem to find someone with the same issue. I read about a lot of cold starting/hard starting issues, but i have never had a problem with that at all...it always starts up within about 1 second of the key turning over. Issue started after i put in some new valve cover gaskets and a new plenum gasket. I reinstalled everything per the haynes i have, and then got all the vac. lines back on according to a FSM that i found online. When I start the truck cold, the idle runs at about 800-1000, which it did before, but the idle is very rough and if i try to drive it it has very little power and misses like a B If i just let it sit there and idle for a few minutes (5-15) it goes back to normal and runs like a champ. it doesnt gradually get better-it just magically idles and runs fine. I removed the connector to the CSI and it didnt change anything..how can i check if its actually sending power to the injector? how long does the injector run when started up cold? I start it in the morning, and after it gets better, it will be fine sitting in the lot at work for 8+ hours, it seems to only be an issue after sitting over night for about 10ish hours. Any ideas, guy? thanks in advance. Please feel free to link me to any previous posts that i may have missed.

The cold start injector runs for i think 3 seconds max, mine isnt working so i wired it straight to a push button, even at -10 it takes just a second of pushing it to fire right up, but i have a check engine light in the real cold, runs iffy till it warms up, then seems to be fine, i havent got the code yet but i think theres a magic coolant temp that changes the fuel mapping and maybe timing, i suspect the sensor is not reading at all until it warms up and the ecm just goes into a default limp mode until it sees the temp, i know the 02 sensor isnt the problem, or the maf, or the coil or distributor, or fuel pump, i do have the egr stuff removed, very possibly could play a part.