I have the following:
rebuilt 350 with roughly 45K on it.
The engine has started something weird that's slowly getting worse.
The engine runs just find until you press the gas peddle more then 1/2 to
3/4 of a inch down, at which point the engine makes a bogging sound, it
almost sounds like there is a exhuast leak under the hood and I have no
power. On a recent long trip, the problem got so bad that I had to
downshift going up hills and I couldn't pass anyone as the engine just
couldn't do anything (lucky for me the v-8 could keep up highway speeds
mostly just above idle). If I did press the gas peddle down, the engine
would lose power and then the service engine soon light would come back on.
It would eventually go out again. I have thoroughly inspected under the
hood and the exhaust is fine, and all the exhaust manifold bolts are tight.
I just replaced the airfilter too. The engine doesn't backfire from leaning
out, and I don't get any black smoke from running too rich. The engine
seems to do this just after it's first started and then once it gets really
warm, on a long trip. Could it be something electronic?
Any ideas here on what's the problem?
I'll stray from the pack and say Catalytic converter(s).
Also, what code was set? Pull codes from the ECM, it would give us a lot
more to go on.
To pull codes from an OBDI(pre-96) car, follow these instructions:
Locate your ALDL connector. In an 80's Chevy half-ton truck, it's probably
under the dash somewhere near your left knee. Take a jumper(paperclip works
just fine), and insert it into the ALDL connector's A&B pinouts. A&B are the
right-most upper 2 pins on the connector.
Insert jumper. Turn key to RUN, not START, and pay attention to your "check
engine" light. It will begin to flash.
It will initiate code-reading by displaying code 12 3 times in a row. Stored
error codes follow the 12s, with the code reading terminating with another
set of 3 12s.
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