911 sc frustrations with CIS

[Dfwflyr]

Ok so I have an issue with this loud sound from the exhaust when the car is at 3000-4500 RPM with the car at open throttle. I changed the muffler and everything else is sealed up so I started looking elsewhere. Now at idle my exhaust smells really rich. It idles a little rough and after 5 min at idle I get some surging for a minuet or two. Something I attributed to the WUR. Then I thought if the mixture is too rich then maybe my mixture is too rich then i have unburnt fuel igniting in the exhaust. So off to try some minor adjustments with the idle mixture last night. One thing i noticed is that the fuel pump runs all of the time, and i dont have continuity across terminal 85 on the relay input when the airflow valve is moved. So im guessing bad safety switch. I tried minor adjustments on the idle mixture and moving it anywhere else will cause the car to start and then immediately die. I returned the mixture screw to its previous position and now at idle the engine just surges 300-400 rpm. Now i think my only option is to take it to a shop unless i can find an exhaust analyzer in DFW to rent. One thing i havent been able to find on the forums is if my issues are caused by the CIS set up. With the fuel pump running constantly am I flooding the engine for startup? If i had a bad WUR what role could it be playing in this issue? Also i cant confirm how the safety switch functions, although i suspect its a metal tab/spring that has to make contact with the plunger. Is this something that can be reset or repaired? I want to do what I can outside of the autoshop to keep the cost low. any suggestions.

[T77911S]

if the WUR is bad it could lower the control pressure making it run rich.
you need to get some gauges and check cold and warm control pressures.

sounds like you turned the mixture screw a lot. it may only take a small adjustment, CCW to lean it out. i dont suggest you make adjustments until you check the control pressures. but, since you have, a small bump CCW wont hurt. if you leave it like that, you are most likely only covering up the real issue, the WUR.

the fuel pump running all the time does not hurt anything. mine was that way for 10yrs.
the switch in the AFM provides a GROUND tothe relay when the engine is not running. this engergizes the relay which cuts it off. removing the ground turns the fuel pump on. backwordds from what you would think but a better design. if the coild goes bad, the fuel pump can still run.
sounds like you have a grasp on things and you should be able to get it going, you just need some gauges. about $100.

there is also a connector on the back of the AFM, make sure that is plugged in. make sure the FP relay is good.

[Dfwflyr]

Thanks, I bought a set of gauges last night but they didnt have the correct threads for our cars. I do have an advantage of a friend with a spare engine with a blown case that I can possible rob a WUR off of and see what changes. Is it at all possible to adjust the mixture without the analyzer? has anyone successfully done it?

[Josh D]

First is to identify what year your SC is. a '78 CIS is not the same as an '83 CIS for example.

[Kyle at Pelican Parts]

As someone who has personally suffered many a CIS/K-Jetronic nightmare, I can say that if you are planning on doing ANY troubleshooting on a CIS system, you neeeeeeed the pressure gauges. You're going to end up pulling your hair out otherwise.

K-Jetronic/CIS Pressure Gauge Set

[vash]

$229?

ouchie.

[Peter Zimmermann]

Originally Posted by Kyle at Pelican Parts

As someone who has personally suffered many a CIS/K-Jetronic nightmare, I can say that if you are planning on doing ANY troubleshooting on a CIS system, you neeeeeeed the pressure gauges. You're going to end up pulling your hair out otherwise.

Kyle, does your tester include the fittings necessary to connect the hoses to the WUR, FD, etc.? How about a supply of proper sealing washers?

[T77911S]

$100 Tool Aid 33865 C.I.S. K-Jetronic Fuel Injection Tester with Case - Amazon.com

yes. yours is VERY close to being right. the problem is you want to know why it changed or why it went form being set correctly to running rich.

i set mine by "ear" or "feel" for years. when i did get an LM2, i found it was right on. one of my checks was like the problem you have. let it idle for a while, if it starts to surge, lean it out just a tad. if it does not , it is good. another check is to rev the motor. when it comnes back down, if the RPM's drop below what idle should be then it comes back up to idle, it is too rich.
if you are right on the edge of these 2 checks, you are good to go.

[Kyle at Pelican Parts]

Originally Posted by Peter Zimmermann

Kyle, does your tester include the fittings necessary to connect the hoses to the WUR, FD, etc.? How about a supply of proper sealing washers?

Hi Peter,

It does include the necessary fittings according to the description from our supplier, but I put a call into that supplier to be extra sure. I'll let you know when I confirm. I will also ask about the washers. I realize that this tool is significantly more expensive than some alternatives that have been suggested in this thread, but it is of an excellent quality. It's a lifetime tool, and I think anyone who purchases it would be exceedingly pleased with it.

[Dodge Man]

Each -0XX WUR works a little differently and you need the one for your motor/CIS year. I had an old -033 installed while I sent my EURO -089 out to Larry. It was making my motor run too lean. I just sold my -045 so no sales pitch. Get the book & gage set(with fittings). If your WUR is bad then Larry at CIS Flow Tech is the man.

[Dfwflyr]

Ok Im going to check the WUR to make sure it is the right one. Now the car has about 20K since rebuild and Im not 100% sure that this is the matching engine. Where can I find out what WUR goes with what CIS/engine number. Im dont want to rule out that I dont have the correct WUR on the car

[Dfwflyr]

Ok I ran the gauge on the control side in line to the CIS distributor. Being in Texas i couldn't keep it cold for long but the cold pressure was around 35 psi. However when warm I was getting 68 PSI and it would trickle down to 62 psi with the valve on the gauge setup open. If the WUR is giving too much pressure shouldnt that be leaning my mixture by reducing flow in the CIS? Now another item of interest was when I checked the AAR. When Hot the AAR was still open (opening like a crescent moon) If i used an alan wrench to open the AAR more and it leaned out my mixture (non metered air) so i at least know the engine runs. Im going to change the AAR (i think it should be closed completely when warm) however a proper functioning AAR valve is likely to make the mixture more rich when it closes off when warm. does anyone have any suggestions? What do you think about the effect of the higher pressure from the WUR?

[javadog]

Ok Im going to check the WUR to make sure it is the right one. Now the car has about 20K since rebuild and Im not 100% sure that this is the matching engine. Where can I find out what WUR goes with what CIS/engine number. Im dont want to rule out that I dont have the correct WUR on the car

Let's start with a few questions...

What year is the car?
US or ROW?
What is the engine type number?
What is the engine serial number?

JR

[Dfwflyr]

I'm not at home soI dont have the engine serial number right now. It is a 1978 3.0L US spec car.

[Dfwflyr]

Im not too familiar witht he vaccuum system on the 3.0L but could a vaccuum leak be causing the rich mixture? it bothers me that i cannot seem to adjust the mixutre at the airflow sensor ( run it rich or lean it out and it dies) and I'm determined to get to the bottom of this.