1994 Chevy Truck stalling

SHAME_101

MEMBER
1994 CHEVROLET TRUCK
V8
4WD
AUTOMATIC
187,000 MILES

My 1994 chevy pickup originally had a 4.3L v6 in it but it had alot of miles and was useing oil so I decided to swap it out for a 5.7L. The 5.7 came out of a 1993 2 wheel drive pickup that had been wrecked. I got the computer for that engine along with the engine. It had 130000 miles on it when I pulled it. Since I have put it in there I have been having problems with it dying when I put it in gear or when I come to a stop so I constantly have to drive with one foot on the gas and one on the break. The guy I bought the engine from said it never did that to him. I have replaced the idle air control valve and that made no differance. About a week after I got it in I took it to a shop and had the timing set and the computer reset and also had a diagnostic ran on it but nothing showed up besides low vacume. The person at the shop said the low vacume shouldnt affect it like that but I dont know. Any help would be appreciated

5 Replies

MASTERTECHTIM

MECHANIC
4,749 POSTS

Does the truck start and idle when cold? Do you always have to keep foot on gas? Can you tell if the iac is stuck open or does it move. If you drive it with your foot on the gas while stopping does it run fine or are you compensating for it running rough? What I mean is are you controlling idle speed totally?

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Friday, May 30th, 2008 AT 11:35 AM

SHAME_101

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3 POSTS

Yes it does start and idle when it is cold. I seems like the warmer the truck gets the easier it dies. I dont know if the iac is opening I dont know how to check that. If I let the rpms too low it runs rough and trys to die but if I keep it sped up fast enough it runs fine. When the truck is warm it will idle for a little while when it is in park but it wont stay running when I put it in gear.

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Monday, June 2nd, 2008 AT 11:20 AM

MASTERTECHTIM

MECHANIC
4,749 POSTS

Did you set the ignition timing? Might have moved a little when you swapped engines. Very critical. Also unplug the egr valve and tap on it with a hammer to seat it and drive truck. Get back to me

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Monday, June 2nd, 2008 AT 12:17 PM

SHAME_101

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3 POSTS

Yes I took the truck to a local shop and had the ignition timing set. I tried tapping on the egr valve and it made no differance. Any other ideas?

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Thursday, June 12th, 2008 AT 2:17 AM

MASTERTECHTIM

MECHANIC
4,749 POSTS

Ok when you said vacuum problem you were having when the truck looked at, do you have a map sensor code? That would drastically affect how it runs. Unfortunately we are going to have a tough time figuring this out on the internet unfortunately. A scan tool needs to be installed and the sensor voltages need to be monitored to further diagnose.