Just tested CIS pressures and need help with results
 

I just tested my pressures on my 78SC with the Pelican CIS pressure test kit. Its a good piece of equipment it seems so I followed the instructions as best as I could. I also have an LM-1 for the A/F mixture readings. I have a warmup issue where the car fires up from cold and runs high idle like up to 2K then after about a minute drops to below 900k and chugs. I have noticed that the LM-1 shows a lean mixure during this time. then after about 5 minutes, the idle smooths out and everything is great. I have checked for leaks and adjusted the timing to 5deg BTDC. Right now, I have to run the A/F rich at about 12.8 when fully warmed up to minimize the warmup issue.

I hooked everything up and made sure I had the valve on the correct side according to the instructions, with the hookups between the WUR and the Fuel Distributor. I started the car and then recorded pressures every minute and here is what I got as far as data.

754pm -- started motor, 2.2bar air fuel at about 13.0. This pressure rose to 2.5 in about 20 seconds and climbed to 2.7 after about 30 seconds. still had high idle which is the norm

755pm -- 3.3 bar, engine still running ok..high idle air fuel 13.3 or so

756pm -- 3.3bar, idle comes down to 800 and engine starts sounding like its going to die, airfuel ratio lean at 14.2, I have to manually adjust idle screw to get rpms back up to 1K. This is what I would like to fix.

759pm 3.3 bar, idle starts to clean up and rise just a bit and A/F starts to come back to 13.7

802pm -- 3.3 bar and idle is pretty good but high at 1250k air fuel is now comming down to 13.3, I manually adjust the idle back down to 1k

805pm -- 3.3 bar and idle is great A/F is at about 12.8 and this is how it stays, I adjust the idle down to 950 and all is well.

So then I turn the engine off and monitor the pressures over a 20 min time frame

816pm 2.2 bar
817pm 2.0 bar
818pm 1.8 bar
819pm 1.7 bar
820pm 1.65bar
821pm 1.6bar
825pm 1.5bar
837pm 1.2bar

At this point I turn the engine back on and let the idle stablize and turn the valve on the CIS tester kit and the pressure climbed to 4.8 bar. This made the engine run kinda rough but it didnt stall.

Im not sure what to make of all this. I recently replaced the filter and the accumulator as these were easy to address. I am a bit concerned about the lean mixture on warmup and I would like to run my A/F at 13.5 or so when fully warmed up. I think this would translate to 5% CO which is what I think is recommended.

Thanks for any help on this...

here is what i see going on. after 20 sec, the 2.2 rise to 2.5 should be the thermo time valve (TTV) opening up and alllowing vacuum to raise the CP. would like to have seen about a .5 bar change, but maybe the .3 is due to warmer outside air. you can always check the difference when it is warm by removing the vac line and checking the CP change.

the WCP looks a little low, but in spec. 3.5-3.6 would be a little better.

here is where the problem comes up. it looks like your aux air regulator (AAR) and perhaps the WUR, think the car is warm. IE, the AAR closes too soon and the idle drops too low because the engine is still cold, you compesate for it be changing the idle, then the engine warms up and the idle comes up, then you lower the idle again to where it should be.

you can always just set the idle where it should be when warm, and live with it. i i dont think i ever let it just sit there and idle for that long when it is cold. i usually hold the RPM's up to 1500- 2k anyway. or i am usually slowly driving. i take it easy out of my driveway and past the judges house, not that he cares. he told me he is in bed and says to himself, there he goes in the little car, time to get up.

12.8 is quite rich, i think i have mine set around 13.8, cant remember now. the 12.8 could be due to the low CP. you can either lean it out , try changing the WCP or buy a new WUR.

i am not big on adjusting the CP's because i believe there is a reason why they are not right, usually it means the WUR is going bad, but you could try raising the WCP to increase the warm up time and lean it out, but you risk getting them all out of wack.
if you raise the WCP, the metal strip(which goes bad) may not be able to bend enough when it gets hot to give you the 2.2 CCP to 3.6 WCP change that you are looking for.

if it was me, i would adjust the mixture and keep an eye on the CP's and just use my foot when it is cold.

I had similar problems this spring. The 4 WURs I had all seemed to not want to move up from cold to warm the way they should. Some didn't even want to move at all. If you want to spend a lot of time going through my travails, I have a couple of threads on it.

If you have (understandably) better things to do I can give you a brief rundown:

My AAR and AAV at first seemed to be operating OK, but when I took the FI components from the engine I found a small hole just starting to wear through in the metal pipe to the AAR and AAV. This was from rubbing on the oil pressure sender and/or the oil cooler cover.

I had an atmospheric line instead of a vacuum line connected to the thermo valve.

I had an open vacuum port on the firewall side of the throttle body area.

My bimetal arm in the WURs I had heated up, but they didn't seem to bend or bend enough.

I sent the WUR to someone to have it repaired with some new components, and recalibrated. When I got it back I fine tuned the settings for control pressures. You may be able to use yours as is since the CPs change, just reset the CPs, as your warm is a little low.

I agree w/ what Tony said above. Your WUR seems to be working OK. You can maybe get the WCP up a little if you want. I'm thinking that it's the AAR. I would check the AAR and piping for leaks. You can also check Pelican Mystery Train. He has a great thread on how he recalibrated his AAR to hold the revs higher longer. That may do it for you.

Somewhere you mentioned a 5% CO setting. That's way too rich. 3 to 3.5% seems to be right for these cars, and John Walker has stated 3.5 is best. I'm not sure, but I think 3.5 is about 13.1 or .2 or so. You can find charts via the internet.

Paul,

thanks for the info and the PMs. Ill check out the Pelican Mystery Train AAR thread and keep reading up on this CIS thing :)

i always suspected that was one of your problems, or at least it was not connected properly. have you had that thread printed to a book yet? :D

my AAR closes pretty quick as i said above. i just use my foot, its only for a minute or 2 a day anyway. plus, i dont think it is good to just let it idle. 1500- 2 k.

the change in AF has me a little confused. stupid question. you are turning the big screw on the throttle body to change the idle speed?

get mixture and idle adjusted right when warm and see how it does.