The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1973 - 1987 Chevrolet & GMC Squarebody Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 10-08-2017, 02:11 PM   #1
Gradleg
Registered User
 
Gradleg's Avatar
 
Join Date: Jan 2017
Location: Warner robins, georgia
Posts: 1
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?
Gradleg is offline   Reply With Quote
Old 10-08-2017, 05:22 PM   #2
Sabaka454
Registered User
 
Sabaka454's Avatar
 
Join Date: Jul 2005
Location: CT
Posts: 183
Re: Yet another 350 tbi idle problem

Make sure the MAP sensor vacuum hose didn't pop off
Sabaka454 is offline   Reply With Quote
Old 10-10-2017, 08:28 PM   #3
chris989
Registered User
 
Join Date: Dec 2011
Location: Boise, Idaho
Posts: 348
Re: Yet another 350 tbi idle problem

Quote:
Originally Posted by Gradleg View Post
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?

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
chris989 is offline   Reply With Quote
Old 10-11-2017, 07:33 PM   #4
DieselSJ
Registered User
 
Join Date: Jun 2016
Location: Phoenix, AZ
Posts: 238
Re: Yet another 350 tbi idle problem

Quote:
Originally Posted by chris989 View Post
third. buy a OBD2 cable to USB
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.
__________________
87 R30 CC Dually, 454, TH400
87 Jeep Grand Wagoneer, 6.5 turbodiesel, 700R4
DieselSJ is offline   Reply With Quote
Old 10-11-2017, 10:53 PM   #5
chris989
Registered User
 
Join Date: Dec 2011
Location: Boise, Idaho
Posts: 348
Re: Yet another 350 tbi idle problem

You are correct, OBD1.
chris989 is offline   Reply With Quote
Old 10-13-2017, 09:24 AM   #6
FarmerDale
Registered User
 
Join Date: Jan 2013
Location: Easton,mn
Posts: 20
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.
FarmerDale is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 05:44 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Copyright 1997-2013 67-72chevytrucks.com