dogging in low gears

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Old 06-18-09, 02:41 AM
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dogging in low gears

My beloved '93 Chevy Silverado (4.3L v-6, manual tranny, 274K miles) has begun to dog it in the low gears. It's slow off the line and seems to have little power in the first 3 gears until you get up to speed, then it runs great. It has consistently gotten 17-19 mpg since I bought it new. Someone said it's possible the catalytic convertor is clogged up. Would this do it? What are some other options? Fuel filter? The plugs and wires were changed last summer. Thanks!
 
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Old 06-18-09, 08:10 AM
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Any of your regular maintenance items, like fuel filter, air filter, plugs, wires rotor, cap can cause what you're seeing.

It's never wasted money to do a complete update on those items if they're over due. Aside from those a MAF or MAP sensor can cause problems like that.

The problem you have isn't gear or speed specific, but rather a diminished performance from the engine. It takes less to keep it going after you reach the higher speeds.

If your cat is plugged the wider throttle openings and higher rpms would dog out. Both represent a higher volume of exhaust with an obstruction. That back pressure can be checked with a gauge through the 02 sensor port. It should be around 1.5lb normal with a 4 lb spike.

You can rent a fuel pressure gauge from an auto parts store to check the pump/regulator. If you are going to check that I would do it before the filter replacement and after to nail down whether the filter was causing a problem.
 
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Old 06-18-09, 05:48 PM
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I agree with Marbobj, regular maintenance items should be checked out, especially with that many miles. When I was looking at work trucks my first experience with Dodge Ram with Cummins engines was one with a bad turbo. It wouldn't pull your hat off in a strong wind until you reached 4th gear. On Cummins, the turbo does all the power work. The one I have now, with 370K screams in all gears, and will pull anything.
 
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