CIS gurus? Mind helping me out?

[ccarpen at earthlink.net (Cris Carpenter)]

At 06:40 AM 5/23/2005, you wrote:
>On 11:23:42 pm 05/22/05 Cris Carpenter <ccarpen@earthlink.net> wrote:
> > If you have access to an earlier-style ignition setup (distributor
> > and ignition module from a car without knock sensor), you could
> > easily test if that pesky system is a possible source of your
> > trouble. Dropping in a distributor with vacuum and mechanical advance
> > systems and plugging in the corresponding ignition module would be
> > quick and tell you if that is where your problem is.
> >
> > We've talked about the rest: CIS system and control pressures,
> > injector spray pattern and output, intake air leaks, fuel
> > distributor... If it were me, I'd try the earlier ignition setup
> > first to narrow the search. Then you can say for sure whether you are
> > talking about an ignition problem or something else.
> >
> > Cris
> >
> >
>
>Well, this problem has outlasted the swap FROM that system of ignition. So
>I don't see swapping it all back as making much difference. I'll keep that
>on the list though. I may swap out the CPR today if i can get it off.
>
>Thanks
>
>Cathy


You won't have to if you know the results of the CIS pressure tests. 
Assuming total system pressure is right (okay don't assume), if the cold 
and warm control pressures are within specs, the warmup regulator (CPR) is 
fine. System pressure should be up around 70 psi. Cold control pressure 
depends on ambient temperature, but should range from about 15-20 psi at 
the low end. Control pressure with the engine warmed up should be around 50.

If you indeed had the whole ignition system (distributor and ignition 
module) from an earlier-style setup hooked up and you had the same 
symptoms, I think that allows you the luxury of ruling out the ignition 
system as a possible culprit. Again, you don't want to assume anything at 
this point in the game. If there is a chance the wires feeding all the 
ignition bits are suspect, try bypassing them with known good harnesses.

Speaking of assuming, are you sure there is nothing going on at the timing 
belt end of things (loose belt, loose toothed pulleys, etc.)? In the old 
days (Listen to me. I sound like an old man. Yikes! I am! When did that 
happen?), we used to see the early water cooled cars tearing their toothed 
crank pulley key-ways.

Like I said, about the only thing you can't test without installing a known 
good one is the fuel distributor. Did you say this car used to have an O2 
sensor? That would imply that it once had a frequency valve. If it is still 
there, and just not buzzing so you don't know its there, that could cause 
the symptoms you describe.

If you have a miss under load and it is regular, you should be able to 
isolate which cylinder it is by disconnecting plug wires one at a time and 
seeing which one makes no difference in the symptoms. I remember a Volvo 
once that had a lack of power and miss under load that we traced to one 
cylinder. Compression was fine, but the intake cam lobe for that cylinder 
was worn down to the point that the valve wasn't opening enough. Vacuum 
gauge tests showed a lot of fluctuation when revving and that gave it away. 
You could have something fundamental like that, or a broken valve spring 
that has enough tension left to give you good compression figures but then 
"floats" when revved. That would also show up as a dramatic fluctuation in 
manifold vacuum when revving (in addition to being noisy).

Good luck,
Cris