I have a 1987 K5 5.7l 4x4. When I bought it, it was showing engine light for a loose or defective prom. I got in there about a week and a half ago pulled the prom inspected it and reinstalled it firmly in place. The engine light went away. That night it was showing low voltage, had the battery and alternator checked, bought a new battery and replaced the voltage regulator. It still shows low voltage at idle (11.7-12.3). Now when I crank it from a cold start it will not stay running I have to keep a little throttle to it, then when I start moving it has alot of lag in the acceleration until it warms up. In the last week the engine light has shown about every emissions code there is! I have cleaned out the egr valve and tryed to make sure all vacuum lines are good. I am at a loss on how to fix it. Any input you can give would be greatly appreciated. This is an everyday driver its the only way I have to go!

Today I changed the distributor cap, rotor, plug wires, plugs, and egr valve. Still acting the same! Still no luck on the solution!

 

Have you replaced the coolant temperature sensor on the top of the intake manifold?

 

I think there's a couple clues in there.
The usual cause of stalling and low alternator output is low rpm. The PCM should maintain a level rpm at 500. What is your idle rpm before it warms?
And I'm sorry but 'every emission code there is'.. is not a starting point to help you.

 

No I havent changed the coolant temperature sensor! Should it be something I need to try?

 

when I bought the blazer it had a code 51-prom. The emissions codes I have been getting since I reinserted the prom are= 13- oxygen sensor circuit, 15- coolant sensor circuit, 32- mixture control solenoid, 32- egr system, 33- map sensor, and 45- rich exhaust. The light starts blinking about 20 minutes after I have cranked it, I can turn it off let it sit for about 10 minutes and the light stays off until I run it for 20 minutes or so again.

Today I also replaced the egr solenoid because it wasnt functioning properly.

 

Have you replaced the alternator? Also sounds like you might have a bad PCM.

 

I havent replaced the alternator but I have changed the voltage regulator. Is the ecm the same as an pcm?

 

Today the check engine light came on again, first time in several days. I checked the codes it only showed code 32, egr and code 45, check evap canister and O2 sensor. I still havent figured out what all the problem is though. Any input would be greatly appreciated. Thank you for your advise you have alre&dy given and any future advise.

 

if the prom was loose you could have a prom that has some burnt circuit in it

 

If the prom has burnt curcuits or any other problems shouldnt it have continued to through the code for loose of defective prom? Is there anyway to test and check?