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Gm Tech (Cam)
Gm Tech (Cam), GMC Mechanic
Category: GMC
Satisfied Customers: 1667
Experience:  GM Grand Master Technician 2007. 14 year experience.
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GM sierra: Bought a 96 sierra 5.7 4x4 recently, was running

Customer Question

Bought a 96 sierra 5.7 4x4 recently, was running rough, hesitation on take off irratic idle after engine warmed up, almost to the point of dying at stops but never did. So proceeded with a tune up. Plugs wires cap rotor, made it worse. Plugged in scanner gave me cranksensor, cam, and maf sensor codes, have replaced all three. Now these were circuit failure codes I did trace wiring , looked for vaccum leaks, re done ground... So recently I replaced tps, egr, pcv, is getting expensive, now it has gotten worst its backfiring thru carb. Not a mechanic but not stupid either. Any advice would be appreciated.
Submitted: 1 year ago.
Category: GMC
Expert:  Toolhut replied 1 year ago.
First I cannot imagine why replacing parts would make it worse unless you crossed some wires. I would suspect gear on bottom of distributor. They are very common and cause all kinds of running issues. I also suspect the codes you had were for cam/crank correlation. does not mean sensors were bad. You need a good scanner to read cam offset when the gear is replaced. should be 0 +/- 1 degree
Customer: replied 1 year ago.
No need for phone call, and yes checking the distributor was the 1st thing I did after initial tune up, went and bought a IACV this morning and all is well. Also I know that just because I got can and crank sensor codes that would not be the reason for issues, but with the mileage on the truck and not knowing Maintence history of vehicle I replaced them. I'm sure you are a very knowledgeable mechanic but you weren't really much help to me at all, no disrespect I just figured we would have talked about the symptoms and you would have asked questions to come to a conclusion not just spit out an answer. I cannot believe I paid for this service also the ads are very misleading before I agreed to terms of this service a window was pipping up claiming to be a mechanic and he was waiting to answer my questions, what a farse.. I truly expect a full refund.!!