injector resistance

I posted in here last fall regarding a '88 Chevy Z-24 2.8 multiport
giving me problems. Right after that the snow fell and I just parked it
for the winter.
Basically, when the vehicle is up to operating temp and I shut it off
for a short time, it will start but run very rough and smell of raw
gasoline. During this time it might actually idle but any throttle
pressure seems to make it cut out worse the more gas I give it, and at
WOT it will develop only about 2500 rpms.
It will pretty much always come out of it after about a minute or two
of manipulating the throttle.
I put a new ignition module on it last fall, thinking that be the
problem, it wasn't , and then I put all three coil packs on it from a
donor car I have, still acted the same.
I just tested the resistance on the injectors and they are SLIGHTLY
high but uniform across the board.
Since the problem occurs almost exclusively after what may be a heat
soak period -- i.e. after being started a short time after being shut
off at full operating temp -- I took the injectors and put them in the
toaster oven and heated them to 225 degrees and then tested the
resistance on them again -- uniform ohms as before but measured about
one and a half ohms higher than cold. (The reason I did that was I
thought it was possible that when one of them got hot it could be
sticking open or something -- don't know how likely that is but I've
tried a lot of other things).
Within the last 25k the car has had a new ecm, ign module, heads,
plugs, wires, MAT sensor, and 3 used coils which didn't change problem.
Anyone have a similar situation with a car of that vintage? It reads
about 160 K but the engine was replaced years ago before I got the car
which I'e had for about 7 years.
Wasn't expecting to have this much trouble figuring out a problem on a
car this old.

James Goforth wrote:
> I posted in here last fall regarding a '88 Chevy Z-24 2.8 multiport
> giving me problems. Right after that the snow fell and I just parked it
> for the winter.
> Basically, when the vehicle is up to operating temp and I shut it off
> for a short time, it will start but run very rough and smell of raw
> gasoline. During this time it might actually idle but any throttle
> pressure seems to make it cut out worse the more gas I give it, and at
> WOT it will develop only about 2500 rpms.
> It will pretty much always come out of it after about a minute or two
> of manipulating the throttle.
> I put a new ignition module on it last fall, thinking that be the
> problem, it wasn't , and then I put all three coil packs on it from a
> donor car I have, still acted the same.
> I just tested the resistance on the injectors and they are SLIGHTLY
> high but uniform across the board.
> Since the problem occurs almost exclusively after what may be a heat
> soak period -- i.e. after being started a short time after being shut
> off at full operating temp -- I took the injectors and put them in the
> toaster oven and heated them to 225 degrees and then tested the
> resistance on them again -- uniform ohms as before but measured about
> one and a half ohms higher than cold. (The reason I did that was I
> thought it was possible that when one of them got hot it could be
> sticking open or something -- don't know how likely that is but I've
> tried a lot of other things).
> Within the last 25k the car has had a new ecm, ign module, heads,
> plugs, wires, MAT sensor, and 3 used coils which didn't change problem.
> Anyone have a similar situation with a car of that vintage? It reads
> about 160 K but the engine was replaced years ago before I got the car
> which I'e had for about 7 years.
> Wasn't expecting to have this much trouble figuring out a problem on a
> car this old.
>

What is the fuel pressure reading? Could be a bad regulator that is
sending higher than normal pressure when it gets hot. Also check the
vacuum line to it. If it is plugged it can cause the regulator to act funny.

--
Steve W.
Near Cooperstown, New York

Life is not like a box of chocolates
it's more like a jar of jalapenos-
what you do today could burn your ass tomorrow!