1990 C1500, Strange Stalling Issue

[zaxobs]

Hey Everybody! First post but I have been lurking for a bit ever since I bought my truck a while back. I have a 1990 Silverado RCLB C1500, with the 350/5.7L & auto trans.

For the most part it idles, drives, and starts up alright (or so it seems.) I get about 30psi of oil pressure at idle and climbs as I add throttle, and my temp gauge sits around 200 when warm. About 30% of the time when I shift out of park to reverse or drive, the engine cuts out and dies. Sometimes I can catch it and keep it alive with the gas pedal, but the stall happens quick. It seems to get worse when warm, but I am not 100% on that since it's a little inconsistent. It also happens on occasion when slowly coming to a stop, and has happened once when idling to warm up in the morning before I use it to go to work. Sometimes it throws a service engine light, but I just reset my ECM installing a new IACV so I'm not sure it's there at the moment.

I have been reading about what I should do to fix it, but I am kind of stuck on what to do next. I have replaced the IACV and done the ECM reset for it (which may have made my idle worse, I have a tach in the mail that I will install when it arrives to get some reference on the RPM). It has a new-ish EGR valve and solenoid, plugs, cap, and rotor but I will be re-checking those this weekend. It has a new O2 sensor, and I will be checking and replacing my CTS if it looks crusty. The throttle position sensor also looks fairly new, but I don't have a way of testing it. I also did a new fuel pump/filter when I bought it because it was sitting for a while b4 I did.

Come tomorrow morning I will try and read if it has any codes to get some more info & update this, maybe check for tension on the trans cable. I have read that the TCC solenoid in the trans can go bad but I think it would stall every time if that were the case, right? I don't really have a place to drop the trans pan to do that (except maybe kroger/payless, they would let me do it in their parking lot)

 

[docstoy]

Did you ck for dtc's before replacing stuff ? After replacing components a relearn needs to be done especially if battery cables cycled or memory reset before a proper diagnose can be done . And before relearn why don't you go ahead and clean grounds at engine and battery cables then do your relearn on ecm, in service manual sticky above it is titled 88-98 service manuals, download fuel and emissions manual, look in symptoms for your complaint and start reading there, that won't cost anything but a little time and it may also help you. Best of luck

 

[zaxobs]

Did you ck for dtc's before replacing stuff ? After replacing components a relearn needs to be done especially if battery cables cycled or memory reset before a proper diagnose can be done . And before relearn why don't you go ahead and clean grounds at engine and battery cables then do your relearn on ecm, in service manual sticky above it is titled 88-98 service manuals, download fuel and emissions manual, look in symptoms for your complaint and start reading there, that won't cost anything but a little time and it may also help you. Best of luck

I should've made it more clear, but I already did a relearn right after putting in the new IACV. There aren't any codes saved. (disconnected battery, waited, reconnected, pulled ECM fuse, key on, wait, key off, fuse back in) It stalled in traffic on the way home today and did not throw any new codes. I'll clean the grounds if I can find one that looks bad. My service engine light only comes on right after a stall, and only for a moment. Don't know if thats normal, it does not stay on after I start the truck back up.

 

[docstoy]

What if you were to pinch the hose to brake booster to see if it changes,but be careful, try parking brake first to make sure it holds truck . Without data from a scanner or a dvm to ck resistance or voltages it will be very difficult to know which way to go but you may be able to look at symptoms in service manual for clues on which way to take for repair.