1993 GMC 5.7 TBI Strange Idle/Driveability Problems

[93SierraZ71]

My 91 k2500 with 190,000 miles has been pretty good to me. Ignition modules, coil and cap and rotor seems to be its favorite things to wear/go bad over the years. I have thrown a new IAC, ect and O2 sensors, and other things on it over the years (just cause). I figure it couldnt hurt either.

You'll get your problem fixed, these TBI motors are great and pretty simple to fix. Sounds like you just got a bit of a odd ball problem.

Yea I've replaced almost every sensor lol. I love the TBI 350s and I'm hesitant to buy a Vortec. My dad had a beautiful '98 K1500 and it had lots of power but the fuel mileage was terrible. He said the worst thing he ever did was trade it in for a 2005 Sierra 1500 which turned out to be a lemon. I really hope I get this problem fixed. My '93 was my first vehicle and truck and I'd like to fix it up and have it as long as possible. Only time it really broke down was when the alternator seized up and sparks and smoke started coming thru the vents and from under the hood. It snapped the belt and I drove it home (only 5 mins away from home, didn't overheat with no water pump)

 

[90W7]

Yea I've replaced almost every sensor lol. I love the TBI 350s and I'm hesitant to buy a Vortec. My dad had a beautiful '98 K1500 and it had lots of power but the fuel mileage was terrible. He said the worst thing he ever did was trade it in for a 2005 Sierra 1500 which turned out to be a lemon. I really hope I get this problem fixed. My '93 was my first vehicle and truck and I'd like to fix it up and have it as long as possible. Only time it really broke down was when the alternator seized up and sparks and smoke started coming thru the vents and from under the hood. It snapped the belt and I drove it home (only 5 mins away from home, didn't overheat with no water pump)

If you like your truck just keep it I say, nothing beats a paid off running truck. I'm pretty sentimental about my 91'. I bought mine in 2001 when I was 16 for $5, 000 and drove it all thru high school then drove it from Alaska to Phoenix for 2 years of tech school and back. I've had a 04',05' and last year I bought a 2013 Silverado but Ill always keep the 91.. Too many memories hehe.

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Find anything out on your truck yet?

 

[chevyman98]

If you like your truck just keep it I say, nothing beats a paid off running truck. I'm pretty sentimental about my 91'. I bought mine in 2001 when I was 16 for $5, 000 and drove it all thru high school then drove it from Alaska to Phoenix for 2 years of tech school and back. I've had a 04',05' and last year I bought a 2013 Silverado but Ill always keep the 91.. Too many memories hehe.

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Nice looking gmt 400. I had an 05 and a 12 sold them and bought me a 92. They just don't make them like they use to.

Interested in seeing if you found out anything as well

 

[93SierraZ71]

Nice looking gmt 400. I had an 05 and a 12 sold them and bought me a 92. They just don't make them like they use to.

Interested in seeing if you found out anything as well

I just don't have the heart to sell my '93 or the '95 even though they need tons of work. And I will NEVER take a GMT400 to scrap. I haven't made any progress yet, but payday is today so I'll see what I can do, kinda focusing on my '95 right now and a new computer is $100+

 

[93SierraZ71]

Well I went out to where the truck is sitting at my parents farm, fired it up and it idled perfect so I took it for a rip up and down the lane way and it's spinning tires and almost no hesitation. I wonder if it's because it's cold this morning... Weird. What do you guys think now? Haha

 

[TylerZ281500]

i think the same thing, runs cold but not hot

 

[93SierraZ71]

Yes but why would it run fine when the air is cold, but also when it's warm + when the engine is hot?

 

[TylerZ281500]

i dont have an answer for you on that, i can just tell you my truck did everything your trucks doing to a T. id check what weve all recmonedned ohming out the knock and so on so forth, hopefully its just a computer and not wiring breaks. mine would also function at high rpms started when i was driving home i couldnt be in low rpms got pissed off it was acting up and floored the ***** all the way home and she drove perfectly. why? not a clue

 

[unclegrandpa5144]

You should check timing. Should be4degrees adv. Try that get back to me

 

[unclegrandpa5144]

When its cold computer will advance timing aotomaticly , then when it warms up retards timing. . I would look there ,chain could b stretched maybe even a tooth missing. Sounds like u checked all other possibilitys . had a TBI myself once . check timing set up in your Chilton's or whatever book your using for info. It all show u proper way to do it. Good luck!