1993 GMC 5.7 TBI Strange Idle/Driveability Problems

[TylerZ281500]

remember you will lose collant replaicng it, id check that, should be cheap keep the old one iuf it doesnt fix it, if its still not fixing it then esc is located inside the computer on a 93, i would check the ohms or what not from the knock sensor and most sensors to see if they are reading correctly at the plug, if they check out then your harness is in tact as well as sensors, if not then you may have a break in your harness or multiple. if all checks out well and it persists with those things checked off and eliminated your computer may be toast

 

[93SierraZ71]

Well I talked to someone about a knock sensor, he thinks It's a waste of money cause they almost never go bad. I will have to check the wiring and everything, I heard the wires in a bad spot and can get melted by the manifold. It is a very good possibility the computers pooched, will an ECM from any '93 with the same motor and drivetrain work?

 

[93SierraZ71]

esc is located inside the computer on a 93, i would check the ohms or what not from the knock sensor and most sensors to see if they are reading correctly at the plug, if they check out then your harness is in tact as well as sensors, if not then you may have a break in your harness or multiple.

Silly question, what is the ESC?

 

[TylerZ281500]

ive had two knocks go bad, just saying, youd have to get the codes from the computer and see which ones match but generally any 93 5.7 4l60e one could work or whatever you have yanno, also oriellys and places like that sell computers as well thats what is in my truck right now since my stock one took a ,

esc is electronic spark control, sometime prior to 93 the module was loacted on a bracket on the intake manifold they relocated it sometime around our year (93)

manifold and harness touching is very possible, if the motor has been replaced and someone ever snagged the harness while pulling the motor and stretched something causing a break it couldve been an issue,

 

[kkirwan71]

Have you replaced the fuel pressure regulator it sounds like you're having the same problem I was


Sent my 3/4 ton iPhone

 

[90W7]

Throw a knock sensor at it and ohm out that circuit while wiggling and pulling on the harness/wires like Tyler said.

If it smells rich then it might be getting enough fuel but the timing sounds haywire. And possibly the ecm is erratically controlling it.

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[93SierraZ71]

Throw a knock sensor at it and ohm out that circuit while wiggling and pulling on the harness/wires like Tyler said.

If it smells rich then it might be getting enough fuel but the timing sounds haywire. And possibly the ecm is erratically controlling it.

I will replace the knock sensor and look at ordering a new ECM this weekend. I think the computers toast. But hey, never hurts to replace parts, they will wear out eventually so might as well

 

[90W7]

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.

 

[danny.jacobus]

Ck Temp sensor or the pig tail for temporary sensor. Have seen a bad ecm do this also. Test ect wiring all the way to ecm. If I remember correctly you should have 5v to the sensor.

 

[danny.jacobus]

Temp sensor.