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Newbie Gmc Guy About To Go Back To My Old Dodge.........help!

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579 Enthusiast

579

Posted
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i just picked up a 1994 gmc sierra. its a half ton 2wd standard cab. my buddy (whom i bought it from) rebuilt the 4.3 v6 four years ago and it ran like a raped ape! problem is between the bigger cam, headers, flowmasters, accel coil blah blah blah the computer needed to be reprogrammed for the motor to run right and after the computer work it did. it has the 4l60e by the way. now all of the sudden it starts running like it's always in a high gear (sluggish out of the hole) like it has a stall converter in it or something and it's sputtereing, backfiring, stalling and over all just plain sucks! did the reprogramming vanish? i can't find anyone to work on the computer again and at the 700 bucks he paid four years ago to have it reprogrammed i'm not even sure if the computer is the problem. any suggestions on any of this? a new motor is 1300.00! i'd try to rebuild this one stock but i don't know whats been done to the heads or any thing else. how about a motor and tranny with no computer controls? does that exist? is there a certain motor/tranny combo that will drop right in and bolt up? man my 83 dodge sounds alot more appealing right now. thanks, brandon

Nytemare Senior Enthusiast

Nytemare

Posted
Posted

Are you throwing any lights? Its pretty much impossible to diagnose this problem as it could be literally a hundred things.

 

I would start with the fuel pressure regulator and get the fuel pressure read. This would tell you if the pump is cooked, or there is an obstruction in the line, it may just be a clogged fuel filter.

 

Also, pull your plugs and check to see what color they are, and measure the gap.

Black = too much fuel

White = too little fuel/water in fuel

Brown = Good.

 

measure the plug wires for resistance, anything below 10K ohms is good, OL (or infinite resistance) is really bad.

 

It could also be all due to your trans.

 

Like I said, there are hundreds of things that "Could" be wrong.

579 Enthusiast

579

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no check engine light but who knows maybe it's disconnected. i will look into that. is it possible that whatever programming was done could be undone so to speak? thanks again.

Nytemare Senior Enthusiast

Nytemare

Posted
Posted

the programming is very unlikely the suspect. Its stored in an EPROM and is pretty stable.

 

I would look into actual mechanical stuff before I checked the program. Your coil is a good place to start after fuel.

 

Remember, the basic 3 things...Fuel Air spark. I have heard stories of guys on here fishing plastic bags out of their intakes, that may be something to look at.

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