Seems like I've been posting in here a lot lately but I have a problem
I'm not sure what the symptoms point to.
'88 Cavalier Z-24, 2.8 mpi, 170K miles, has intermittent problem both
with hard starting and power loss.
Sometimes I go to start it and it will fire a time or two right away
but then I have to crank it another 10 seconds or better without it
firing at all, but I can always coax it into starting by manipulating
Also, when I am driving it it will lose power and surge, then come out
of it, etc.
It had a starting problem about a month ago and it turned out to be a
leaking injector flooding the engine, which I replaced.
Within the last 25k miles, the car has had:
new MAP sensor
New heads, plugs & wires
New intake gasket and injector o-rings
Also, since I thought the symptoms pointed to a faulty ignition
module, I replaced that, but the problem remained.
Fuel pressure is about 36 psi with engine running, althugh I did note
that the pressure remains there at any throttle position, and also with
the vacuum disconnected from the fuel pressure regulator. I know this
indicates a faulty regulator, but I don't think that would cause the
symptoms (starting, etc.) seen here. Especially since the pressure
holds steady with engine shut down.
I inadvertently left the MAT sensor unplugged after changing the ign
module, and hence got a check engine light alerting me to that fact. I
plugged it in and light went off.
I just checked the codes and got one for MAT sensor, naturally, and
also one for "lean exhaust."
This has never had an O2 sensor replaced in the 6 years I've had the
car. But I wouldn't think that would come into play with cold starting
when the vehicle is in open loop.
The problem seems ignition related. Could a knock sensor go bad and
cause the ECM to make the ign timing go crazy?
The EGR moves freely by hand and there are no codes for it.
Just wondering if anyone has any suggestions, TIA