Yet another 350 tbi idle problem
 

My grandpa restored his 1987 4x4 350 tbi silverado for my 16th birthday and as his dying wish to see it in its orignial condition. It now has perfect black paint and really nice interior but since he passed away this truck has been problem after problem. When i fire it up it was idle smooth for about 5 seconds then idles really lumped and backfires through the exhaust and spits black smoke i have to keep my foot on the gas or else it sputters and dies after about 1 minute or 30 seconds of this it mellows out and idles perfect. This only happens when i start it. . Ive replaced the iac, both coolant sensors, and the egr. Is there some thing im missing? I recently had my ecu replaced bc some water got on it while i was driving. This started after my ecu went bad and the idle has progressivly got worse. Also my transmission keeps down shifting into 3 and only locks down some times? Do yall have any tips or know of anyone in the midlle georgia area that is good with tbi and can help me out?

Re: Yet another 350 tbi idle problem
 

Make sure the MAP sensor vacuum hose didn't pop off

Re: Yet another 350 tbi idle problem
 

What ECM did you replace your original with? I believe you should have a 1227747. after that, there is a mask code for all the different configurations. (v6 v8 auto manual etc)

second, you need a heated 02 sensor. the oems never work well because they are too far from the manifold.

third. buy a OBD2 cable to USB

fourth download WINALDL for free.

with the software and cable you can ssee exactly what is going on. I fought mine for a month. Little things like the truck thinking is was in gear when it was not.

PM me to walk you through the process. should be easy peazy.

Chris

Re: Yet another 350 tbi idle problem
 

Should be OBD1.

Sounds very rich. As someone else stated, check the MAP sensor.

Quick check - when engine is running, do you see fuel dripping or running out the bottom of the injectors? It should be spraying in a cone pattern with no streams or drips.

Where is base timing set?

What is your fuel pressure?

For the transmission, check the adjustment on the TV cable.

Re: Yet another 350 tbi idle problem
 

You are correct, OBD1.

Re: Yet another 350 tbi idle problem
 

How fresh is the gas you’re using? Recent experience with an ‘87 showed that fresh fuel solved a couple vexing idle issues.