What is the problem?

SLIMTHUGG

MEMBER
CHEVROLET S-10

I have a 1992 gmc sonoma with aobut 153000 miles and its a 4.3 liter and my idleings a little rough I replace the map sensor, ignition module, spark plugs, spark plug wires, distributor cap and rotor, and the o2 sensor and I still cant figure out what the problem is I also checked for any vaccum leaks but that isnt it either. I was just wondering if you could give me a couple ideas what it could be? :)

6 Replies

SERVICE WRITER

MECHANIC
9,123 POSTS

Sometimes carbon build up can be a problem as it collects on intake valves, iac motors and throttle plates. Worth cleaning them regardless if it solves it.

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Saturday, March 24th, 2007 AT 7:23 AM

TRUEFIRE04

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35 POSTS

Yeah use this stuff caled Seafoam / Motor Treatment,
run it threw your brake booster vacum line....you will see alote of smoke thats ok...its the injectors being cleaned, also put have of the bottle in your gas tank.

when putting it in your brake booster line, just poor slowly the line will suck it out, make sure you do it slow though....so it get all clened, and your idel will , should drop back to normel....mine did

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Tuesday, May 1st, 2007 AT 7:36 AM

SERVICE WRITER

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I'll second that on the seafoam, but disagree on what you're cleaning. By putting into the vacuum line (as you should), your bypassing the injectors and putting it directly into the intake, cleaning some of the intake but more importantly the intake valves.

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Tuesday, May 1st, 2007 AT 3:42 PM

TRUEFIRE04

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Well you also have to put half a bottel in the tank, or get 2 bottels and 1 in the vacumline and 1 in the gas tank.I did both. And the truck rund great

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Wednesday, May 2nd, 2007 AT 1:25 PM

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I was always afraid of putting it in the tank. Some of the fuel pump manufacturers said that it could damage the pumps, so I just stayed away from it. Might be their way of explaining away a warranty? I see on the can about adding it to the tank and the it's a fuel stabilizer too. Didn't know that!

I get a little leary stepping on what may be thin ice, but I heard enough other folks adding it like that and it seems like there haven't been problems.

I friend had added acetone to his tank, and had great performance results, within a year he had to replace the pump. Coincidence maybe?