Some CIS guidance (long)
 

First off thanks to tirwin, boyt911sc, Jim Williams and all the others that sought their advice for their CIS issues to create quite a database of CIS knowledge here. Even with all this info I (and others) seem to still have questions.

Car is 79SC ROW stock with exception of SSIs and pre 74 muffler. I have done the following to the CIS system:

Ignition timing set per spec and seems to advance properly.

Modded the 045 WUR to be adjustable

Re-peened the pivot rivet on the 209 AAR and tested in freezer and than powered with 12 volts. Even thou the OHMs were in spec took about 15 minutes to close the shutter. The shutter was so loose on the pivot it would not close.

Replaced all vacuum lines with the exception of the large ones for the AAV & AAR.

Replaced all the intake runner to airbox rubber sleeves.

Replaced all intake gaskets.

Replaced the brake booster line to body.

I made up a air pressure regulator to pressurize the airbox via the brake booster port and with about 10 psi and the only bubbles visibly found were a few tiny ones near the decel valve and sealed them up. I know I'll need to do a more thourough submersible test sometime down the road. I did use a propane torch around where ever I can reach and no difference in engine sound.

If I remove the oil cap the engine really stumbles, if I pull the "T" off the decel valve the rpms rise but very slightly.

If I put a vacuum gauge on the T or the distributor it pulls a steady 11 in. Hg.

This leaves me to believe I don't have a large vacuum leak anywhere.

I made up a set of fuel injector test bottles and at first they all dripped a drop a second. All of them so I swapped out a couple with nearly new spares I have and same drip. I backed the A/F mix 3mm screw in until they stopped. Car would start and in seconds stall, no matter how many attempts.

So I enrichened the A/F in increments until it started and when I tested the injectors the had the drip again but less than a drip a second, so better but not right. To get the idle down to under 1000 rpms I had to screw the idle air bypass screw out a lot of turns, I thought it might even screw out.

So when the engine was warmed up it idled great, started and restarted great the only backfire was in the exhaust if I ran the rpms up and suddenly released the throttle and only one pop each time. It was like this even if I let it sit a half hour.

So I figured the next step is let it sit over night and try it stone cold (40 degrees).
It started but with a lot of stumbling and intake backfires enough I could hear the pop off valve getting a work out. Not Good. After maybe a minute or two it smoothed out and ran fine.

Pressures:
Temp 10C/50F
System - 3.8 bar
CCP - 1.8 bar
WCP - 2.6

Where would I go next to:

Eliminate the injector drip, it will drip before it sprays and the spray test showed good pattern and even amount in each container. Good resistance and very slight movement on the air flow sensor to get full spray pattern.

To have the air bypass screw not so many turns out if it is a problem.

And the intake back fires eliminated. Biggest concearn.

The only device I do not have any dealings with is the AAV and the hose circuit to and from it and the AAR hoses. How could I test the device and hoses in situ if this is a possible source of my troubled CIS.

Thanks in advance

Terry

Terry,

Troubleshooting your problem now is a lot complicated due to your tinkering the mixture setting. The AFM (air flow metering) unit was set at the factory with sophisticated calibration equipment for fuel/ air ratio and the access hole was plugged. So that people would not be able to tweak or alter the setting specially those who do not understand how delicate this setting was. Any way, first thing first. Let's get the engine to start and run at the first turn of the ignition switch. This is my main criteria of a well sorted CIS engine. To be able to start the engine regardless of weather for a car regularly driven.

There were other things that caught my attention in this post:
a). WUR-045 (adjustable). You don't need to adjust your fuel pressure seasonally and if you did, you have an existing problem you are ignoring.
b). You need a good working WUR and AAR. Test your WUR. No need to test your AAR, that is going to the dumpster.
c). Your fuel injectors should not drip when you do a FP test run. If they do, you'll have a very good chance of a back fire during a cold start.
d). 11" Hg (vacuum pressure reading) is too low for you engine. Try to measure your manifold vac. pressure when the engine is at operating temp.
e). Check the opening pressure of the decel valve.
f). Your WCP is too low.

Last but not the least, check the condition of your air box. Cracks at the bottom side of the CIS air box is almost impossible to detect when installed in the engine. Even if the engine is out the chance of having a good reliable test for leak is hard to achieve. You have to either vacuum test or pressure test the air box to confirm the absence of air leaks otherwise, you are hoping that it is good and not leaking. It could be good and leak-free but you don't know until a test is done. BTW, does your air box have the spider plumbing inside it?

There is something I like to request from you. Could you post the ID # of the following:
WUR-045
AAR- 209
FD -???
TB (throttle body)-???
AFM (air flow meter)-???

Just need the last 3 digits. Thanks.

Keep us posted.

Tony

Hi Tony,

I meant the 3mm mixture screw on top sorry about that. Last winter I had to do an engine drop and
did the typical seal service and most of the CIS rubber. It was running very rich. Not to add too many numbers
it was way out of spec. According to what I figured the pin needed to be pulled up. That was when I did the
pin mod on it. while at it I did the repair to the AAR.

B) The WUR changes pressure from CCP to WCP with in a few minutes, the AAR shutter closes but it takes about
fifteen minutes. So the seem to work??

C) The dripping fuel injectors are a concern, and when it was cold this morning the intake did have small backfires.
I know this will eventually create big issues.

D) I'll do another vacuum test next time it is up to temp. Where is the best place to test from?

E) How can I test the decel valve? I figure hook my vacuum pump to the vacuum port on top but how will I know when it opens?

F) How can I raise the WCP up?

The airbox has no obvious cracks in any smooth plastic area I pressurized the box thru the bake booster port and did find
some tiny bubbles in the back left corner at the seem and I sealed it up but have not retested. Next time it is off
I will do a pressure test in water. Right now I can only assume it is at least functional.

What is the spider plumbing? I see only the air flow sensor arm and the pop off valve. So not seeing anything obvious
does this mean no?

Here are the full part numbers, I just pasted them from another file I have.

Fuel Distributor - 0 438 100 031
Throttle Body - 0 438 120 076
AAV 0 280 160 400
AAR 0 280 140 209
WUR 0 438 140 045
Decel Valve ???

Terry

Decel Valve........
 

Terry,

The decel valve # is 0-280-160-111. Are these numbers same as with yours? Thanks.

Tony

system pressure is low and WCP.
if you do not have vacuum to the WUR the WCP will be low, around 2.6-2.8bar

Tony,
Here is the number for the air flow sensor:

0 438 120 070

And while at it I confirmed the Decel Valve as 0 280 160 111

T77911S - I did check vacuum to the thermal valve but not thru it, should have but I'll check it later today when I recheck the vacuum at operating temp.
The valve does heat up to the touch so I know it is getting power. Is this the same power source as the TTS, WUR and AAR?

Terry

I have a question. Terry said that when he removes the oil cap, the engine stumbles. I'm not sure what he means. If he means the RPM's drop, isn't that an indication that there probably isn't a vacuum leak?
thanks
Dave

Terry,
The Thermal Vacuum Switch, AAR and WUR are all on the same power circuit from the 14 pin connector.

The thermo time switch and cold start valve are on another circuit tied together from the starter solenoid on your car.

What is your CO reading when fully warm at idle now that you have adjusted the mixture?

you need to fix your pressures first. you cant do anything until they are correct.

Throttle body.........
 

Terry,

Could you double check the ID # of the throttle body? 0-438-120-XXX is for the AFM. I could be wrong (?). Thanks.

Tony

Tony, just checked the AFM it is 0 438 120 070 I can not see the throttle body number, where on it is the number? It is possible I used the AFM number by mistake when I noted the numbers, that was some time ago.

Dave, yes stumble/drop in rpms when the cap is removed and is quite noticeable. I don't think I have a large leak source but micro cracks in the airbox, air bypass from the AAR, AAV is possible right, and that is one area I can be trying to adjust out of the wrong way.

Thanks Dennis, for the info. The AAR, WUR and TVS I can test alone, I'll need an assistance for the CSV and TTS to test during cranking. The TTS I guess can be Ohmed out alone. I need to get a flex tube for my Heathkit Gas Alalizer, I'll find something that will fit.

T77911S, what to do about the system pressure? Do we all agree this should be first in line, I can adjust the CCP on my WUR but also the WCP is low. I will verify this afternoon that the TVS is passing vacuum thru it.

I will also recheck my fix on the AAR to make sure it is open cold and closed warm,thanks to the handy test connector from Dennis.

I'll report back soon.

Terry

i would check fuel volume out of the pump. has the fuel filter been changed. my sys pressure has dropped .3bar on my 930, i think it is due to the filter.

fuel dist or sys pressure regulator could cause low pressure.

i did a fuel pump test and in 30 seconds I nearly filled a 2 liter bottle and a pressure gage attached to the fuel feed line produced about 100 psi in a matter of seconds.

So onto the fuel distributor and pressure regulator. Any suggestions of best methods?

Terry

Please elaborate on your test method........
 

Terry,

How did you get a 100 psi. fuel pressure reading when your were checking the flow rate? Where did you break the delivery line at? Getting a 100 psi. with an open line is not physically possible!!!! Keep us posted.

Tony

Message received.......
 

Terry,

Got your email and your explanation makes sense. I interpreted it differently from your recent post. Anyway, the 100 psi. reading directly from the FP is good. But the system fuel pressure you at 3.8 bar is too low!!! Do not make any adjustment with the shims/washers until you have confirmed the the primary valve is not leaking. The spec. is about 5.0 bar (72 psi.) and for the primary pressure to drop or change this much could be caused by some leakage (?). We don't know at this point.

I would suggest to replace the o-rings and get another measurement. If you need some assistance with your FD, I could look at it after I return from my trip in mid-May. Keep us posted.

Tony

Just an update, still have not solved all the issues but until I know the integrity of the airbox and FD internals I am just chasing my tail. In the next week or so I'll remove the suspected parts and get them off to Tony for his expertise.

It will be July before I'll be able to reistall them and at that time I'll update this post. Hopefully it will be all good news.

Terry

Coming home......
 

Terry,

I will be back home May 15 (Thursday). There are 4 WUR's and a FD from fellow PP members awaiting testing and calibration. Send me your air box, FD, WUR, and AAR for testing and evaluation. Testing is FREE. PM sent.

Tony