1994 Chevrolet Truck lost power

CSA1

MEMBER
1994 CHEVROLET TRUCK
5.7L
V8
4WD
AUTOMATIC
255,000 MILES

Was driving home, truck was running fine, suddenly it started to act like it lost power. Ran that way for 3 or 4 miles then suddenly took off like a rocket & had all kinds of power. Ran fine again for a few miles, then back to no power. Stomped the gas, it kicked down but lacks power badly. I replaced the MAP & EGR in it a few months back & it also got a new fuel pump, so ruling those out for moment. Im stumped at the moment. Shows coeds 33 & 44, I know 33 is MAP & 44 is O2, but as mentioned, has new EGR & MAP already put on it

5 Replies

JACOBANDNICKOLAS

MECHANIC
108,179 POSTS

Have you checked the catalytic converter to see if it is plugging? When it is running poorly, see if it gets red hot.

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Sunday, August 9th, 2015 AT 8:36 PM

CSA1

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78 POSTS

Converter was removed years ago. Has headers now

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Monday, August 10th, 2015 AT 10:13 AM

JACOBANDNICKOLAS

MECHANIC
108,179 POSTS

When the exhaust was modified, what did you do with the O2 sensors?

Also, even though the fuel pump was replaced, there could be an issue there. You should check pressure while it is happening.

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Saturday, August 15th, 2015 AT 7:25 PM

CSA1

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78 POSTS

Ended up being the MAP sensor again. 3rd one in less than a year, no idea whats causing them to go bad so fast

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Monday, August 17th, 2015 AT 12:33 AM

JACOBANDNICKOLAS

MECHANIC
108,179 POSTS

Glad you found the problem. If you are getting an aftermarket (inexpensive) sensor, that could be part of the problem. Most emission parts (even aftermarket) have an extended warranty, so check that out.