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99 GMC K1500 - running really rough
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Jimbo214
New User
Jan 26, 2011, 10:40 AM
Post #1 of 2
(2263 views)
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99 GMC K1500 - running really rough
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Hey folks need a little help in figuring out what to do here. I have a 99 GMC Sierra, K1500 4x4 truck, its the old 99 body style, 5.7 liter motor. This thing has been running rough for about a month. When I pull out into traffic and really get on the accelerator the engine spits / sputters / misses, loses power and will not get above 35-40 miles as it continues to spits / sputter / miss. Now I can pull out and ease up to speed, taking about twice as long, and it will run ok. Once up to speed and going up incline I can feel it wanting sputter / miss or a slight slip feel almost like the transmission slipped. I can be in neutral and rev up the rpm's and it will never miss a beat. It only does the spit / sputter /miss thing when it under a load so to speak. I have also noticed in this time that on occasion, 1 out of 12-15 times, it appears that the engine is not getting any fire. I turn the ignition and it just turns over but no real fire. I have to try 3-5 times before it will crank and it will run rough for just a few seconds and then its ok. The check engine light is on and I am getting a 0174 code or a lean / rich bank 2. Here's what I have done so far. Fuel pump / pressure checked, new fuel filter, new air filter, mass air-flow sensor cleaned, new plugs / wires. Still having the problems. What do I try next? I did not change out the distributor or rotor button with the plugs, should I try that next? What about fuel pressure switch or crank sensor?
Any suggestions would be much appreciated.
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Loren Champlain Sr
Veteran
/ Moderator
Jan 26, 2011, 4:51 PM
Post #2 of 2
(2253 views)
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Re: 99 GMC K1500 - running really rough
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Jim; I'm more concerned with the misfire than the P0174, although, they could be one in the same. But, the very first thing I'd look at would be the distributor cap. These type caps are very prone to cross-firing. Many times, you won't even be able to see it with the naked eye. If it's old, or you see moisture, replace it and the rotor. Now, back to the P0174.... This could be a result of the misfire, or the cause. If this is an actual misfire, you should be getting P 300series codes. i.e..
Cyl. 1= P0301, Cyl. 2= P0302, ect... What fuel pressure are you seeing? Should be 60-66psi. Have an exhaust analyzer test. High HC? Low, to none HC?
Have you had the injection system cleaned? (this is done with a machine....not the stuff you pour in the tank) Could be a dirty, plugged, or bad injector.
Loren
SW Washington
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