Bogging and knocking

Tiny
STANGRUN
  • CHEVROLET BLAZER

I have a 1998 Chevy S10 Blazer 4.3 Vortec V-6 4WD mileage is 124,000. It has recently had a full tune-up and transmission service. I have replaced the following: plugs, wires, cap, rotor, pcv valve, fuel filter, air filter. I have kept up on my oil cahnges as well. It has lost a lot of power and stuggles, knocks and pings. It idles ok but it has trouble getting up to speed and can barely mantain 65 mph on the highway. It bogs and is being held back. My gas mileage has gone way down. I checked to make sure my cat isn't plugged and it's ok. It obviously seems to be running lean. This problem came on very suddenly. I've had it scanned and all it says is random mis-fire. No specific codes come up. It doesn't seem to mis-fire at idle only under acceleration. I thought it may be the fuel pump as it is the original pump. But I was told that electric pumps don't slowly go. They either work or they don't. I am pulling my hair out over this problem and any help you could give my would be greatly appreciated.

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Thursday, June 7th, 2007 AT 10:14 AM

3 Replies

Tiny
E40WATER12
  • MEMBER

I think 1998 Chevy S10 Blazer 4.3 Vortec V-6 4WD, doesnt have a cap or rotor, Its got coil pack igintion system, distr-less, I think if you replace youre coil packs should correct youre mis-firing problem, Also has youre fuel fitler been replaced as well.

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Saturday, June 9th, 2007 AT 6:42 PM
Tiny
BOOTDOG
  • MEMBER

Fuel pumps can be weak, check the fuel pressure, if it's low enough it will cause the lean symptoms you described.

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Sunday, June 10th, 2007 AT 7:16 AM
Tiny
STANGRUN
  • MEMBER

I found the problem. It turned out to be a faulty mass air meter after all. The replacement that I bought at first was defective. I tried another one and the truck is fine now. And by the way 1998 Blazers do have caps and rotors. It doesn't look like a traditional distributer cap but that's what it is. Thanks to evryone for all the help.

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Sunday, June 10th, 2007 AT 3:37 PM

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