Trying to help out one of my guys who bought a 91 Lumina APV 3.1L from the
state auction. 137K miles, wasn't running long when he bought it. Changed
out a variety of things, first on the list was a new battery, then ordered a
new eprom chip, since it was missing from the computer. The computer looked
like it had been changed out, and whoever worked on it last gave up, since
there was no eprom chip in it, and was left hanging on the floor when
Next he installed new plugs, wires, cap and rotor. Oil pressure sending unit
was missing, had a plug in the block, new one was purchased and installed,
seems to be working fine now. Fuel filter was changed, the old one drained
into a jar where where we could see there was a considerable amount of trash
So now the computer gives no codes when it's started when cold, and dies
completely after getting warmed up, generally right at 15 minutes of
running. Everything seems to shut down, ignition and TBFI when it dies.
Computer has given out a variety of codes when the motor dies, for mapp
sensor and O2 sensor. Those were replaced on the assumption that he's rather
know he had good parts than to wonder about them. Knock sensor shows 12V
when running, book says it should be 6-10V, and does not retard when he
clanks on the side of the block.
Thought it was a good chance the crank sensor goes out when it warms up, but
the Haynes manual doesn't show one for that engine/motor combo, and he
doesn't see one. Although most models seem to have one, this one apparently
doesn't, or we're too ignorant to spot it.. ;-).
The ECM module hasn't been tested, although I thought that should have been
one of the first things checked. Also the fuel pressure and signs of water
in the gas hasn't been checked, but I believe we're going to check it in the
Any thoughts on what could be causing this? Appreciate any replies, if more
info is needed, I can pass it on....