CIS problems with 82SC

Kirk911SC · 04-30-2005, 07:13 AM

I've been having problems getting my mixture set correctly.

I recently replaced a defective WUR (tested with pressure gauge) and I can't seem to get the car to perform properly.

Here is a list of what has been done.

About 2000 km ago:

-new plugs - Bosch W5DC
-new fuel filter
-new air filter
-new distributor cap
-new rotor

-new coil about 6 months ago
-new Magnecore wires about 6 months ago

-Timing has not been changed from prior settings - would easily pull to 6000 rpm with no problems.

-Lambda disconnected I believe.

Problem with car right now is this:

-Car starts and idles fine (~1000 rpm)

-After cold start anything but light throttle will cause backfiring - sounds like through intake.

-After warming up for a bit the backfiring problem will only occur with heavy throttle, but there is really poor pickup.

-Car will only accelerate with gradual increase of throttle or it will "fall flat".

-Engine will accelerate to redline if done slowly, with no backfiring.

- Seems like exhaust backfiring on ocassion through exhaust.

I thought an intake backfire indicated lean, and an exhaust backfire indicated rich? I seem to have both sometimes!!

I've tried adjusting mixture in small increments up and down and I can't seem to get it set properly. I don't have an exhaust gas analyzer.

Any ideas??

Kirk

stlrj · 04-30-2005, 07:29 AM

It sounds more like an ignition problem and not mixture. I've had problems with Magnecore wires in the past. Even brand new Clewett ignition wires can be a problem if not installed properly.

Do a search and you'll see what I mean.

Joe

Kirk911SC · 04-30-2005, 11:25 AM

Any other ideas?

Paulporsche · 04-30-2005, 12:08 PM

I am wondering if you have vac leaks which have been masked by a mixture that has been enrichened. Did you test the new WUR w/ the gauge? What CPs did you get and @ what temps?

If you check, you will find lots of test procedures for these types of symptoms. Vacuum leaks, a bad AAR, AAV, WUR decel valve, air flow sensor plate or fuel distributor plunger are all possibilities. You really have to systematically go through all this stuff.

You may want to replace your O2 sensor w/ a new one.

Your car also has temp and throttle position switches and a frequency valve that affect enrichment. These can go bad, or have a faulty elec connections.

Typically you should have a higher idle speed during warmup. This could mean your AAR is bad or the WUR is off. What is the idle speed when warm?

Do you have a Bentley manual? Between that and the search function, you should find lots of help.

Kirk911SC · 04-30-2005, 01:14 PM

New WUR was tested, and fell within proper specs

System pressure - 75 psi
Cold Control pressure - 25 psi @ approx 50 F
Rest pressure - 22 psi
Warm control pressure - 50 psi

O2 is disconnected. Idle speed 1000 rpm

I just adjusted the mixture again.

Went rich about 1/2 turn and idle was fluctuating wildly with car almost stalling. Went lean until surging stopped. Took car for a drive. No backfiring, and great power (more than I ever remember having!) temporarily. Power would seem to come and go. Keeping moderate throttle in a steady position the car would acclerate hard, then hesitate, then pull hard, then hesitate...........what's going on here now?

Sometimes the car will pull very hard, and then sometimes it won't??

Seems to me that I'm close to solving it........

And I have the Haynes manual, and two CIS manuals. No vacuum leaks apparent. Car is better than it was this morning, but not quite right.

I hate to take it my mechanic.............

Kirk

Kirk911SC · 04-30-2005, 05:24 PM

Ignition advance problem??

How much vacuum should there be on the vacuum advance hose?

What would happen if the advance hose was plugged with crud (i.e. no vacuum advance)?

Retard hose has lots of vacuum at idle and falls off with throttle - like it is supposed to do.

How much should the rotor turn to check advance springs? Mine barely moves at all.

Kirk