CIS Pressure thread

[9dreizig]

Guys,
I'm still chasing a rich condition and am now looking at testing all the CIS pressures. So this time I'm going to start a ultimate thread with all the readings and pictures etc..
I want to check my return pressure but don't have an adapter for my CIS pressure kit,, Anyone know where to get an adapter for either one of these spots ? I borrowed the pics from Jonny wishbones leak thread

The one on the left is bigger than anything that came with the kit and the other is a banjo fitting

[RarlyL8]

The pressure is measured between the WUR and the fuel head.
In the picture below you can see where the inlet line to the WUR has been removed and bolted to the pressure gage. The other end of the pressure gage then bolts back into the WUR.
To check system pressure you turn the in-line lever to deadhead the flow which loops back to the fuel tank.

[9dreizig]

Brian, my intent is to document ALL of the pertinant pressures.. Right now I think my problem may be in the return pressure and I don't know where to get an adapter for either one of the circled areas I want to tap into..
T

[RarlyL8]

You should be able to measure return (system) pressure as I described. Do you have a problem between the WUR return line and the fuel head return line (in other words a problem inside the fuel head)? What symptom points towards a return/system pressure issue?

[9dreizig]

Brian I thought the return pressure was measured between the fuel head as it heads back towards the fuel tank.. that's the two parts I had circled.
Anyway here are the symptoms with no air filter ( in case you may have thought it was an airflow issue) it starts no problem . It idles at 14.5-14.7 AFR
When I rev it up to say 3-4k rpm it instantly goes rich (10-11 AFR or more) with NO BOOST
I've replaced my digital WUR with the stock one,, same issues
Also when I had my DWUR installed it showed control pressure of 4.5 -5 at cruise (should be in the 2.5's or so I believe)
Now I've replaced all of the gaskets on the injection blocks, checked everything for vacuum leaks (done the carb cleaner spray test)..
Oh and I also rebuilt the recirculation valve..
So my conclussion is it's got to be a fuel system issue
What do you think?

[JBL930]

Wouldn't that simply point to your control pressure being too low for normal driving (cruise). have you tried raising the control pressure for this, then leaning the idle out via the CO screw?

[RarlyL8]

Control/system pressure should be ~85psi stock all of the time. Warm pressure at cruise as measured after the WUR is half that.
Internet diagnosis is difficult at best. Have you checked for exhuast system occlusion?

[9dreizig]

Brain, I've checked the exhaust and even changed out turbos. That was one of my original thoughts. I have my euro exhaust on there that works like a champ on my 80 turbo

[mooney265]

You said: When I rev it up to say 3-4k rpm it instantly goes rich (10-11 AFR or more) with NO BOOST

So, do you do this with the CIS gauges hooked up? If so, what is happening with your control pressure during this 3-4k rev?

Your control pressure should remain constant until boost is sensed... If it's dropping suddenly durning the "rev" then my guess is that there is something wrong with the WUR/settings... If the pressure isn't changing during the "rev" but you still see AFR's dropping suddenly, then my 2-cents is that the plunger is being pulled down too far allowing too much fuel for too little air???

[9dreizig]

Thanks Mooney, I'll be looking at this probably later today or tomorrow ( tough to do it alone).

[RarlyL8]

When I rev it up to say 3-4k rpm it instantly goes rich (10-11 AFR or more) with NO BOOST

So this happens with no load on the engine? Like sitting in the garage and blipping the throttle?

Stupid question but have you verified that this reading is correct and there is no issue with your detection equipment and O2 sensor placement?

[9dreizig]

Well I am pretty sure I"ve got a good O2 location ( middle of the muffler, downstream from the turbo) and even if I didn't 5-8 mpg on the highway and a HUGE rich smell.
So yes just sitting in the garage.. I'm going to have my cute blonde friend over and help me blip the throttle so I can watch the control pressure.
I think it keeps pointing towards the fuel head..

[9dreizig]

Update,, went out and using the pictured set up.. Engine cold 6 degC I get the following
System pressure 6.5 bar
Control pressure 1.9 bar

On another note I also did a pressure check and after 20 min still had 1.6 bar so I have a good fuel accumulator too!

I am waiting for my friend to come over so I can see what the control pressure is running and what happens when she bleeps the throttle

[RarlyL8]

Do you have a rebuilt or modified fuel head by chance?

[9dreizig]

Brand spankin STOCK

[RarlyL8]

What happens when you keep the revs at 4000rpm sustained? Do the AFRs eventally go up?

[9dreizig]

Nope,,drove that puppy from LA to Tahoe a few weeks ago with my laptop in the copilot seat and watched the control pressure hang out at 4.8 and the WUR was commanding 5.0 ( the max that UTCIS allows) all the while the AFRs were in the 12 range. And theoretically it should have been so lean it wouldn't run

[9dreizig]

Brian, just tried to call the CIS Helpline,, but you didn't answer LOL

[9dreizig]

Ok cute blonde just came over,, started it up control pressure slowly climbed into the 2's had her bleep it to 3000 rpm control pressure didn't blink but the AFR's went to 10 and change..

Mooney, does this point to the plunger in the fuel head ??

[patkeefe]

Isn't the plunger travel mechanically limited by the sensor plate linkage (I'm thinking of my SC, which is opposite the 930 head, but principally the same)? If you go way rich and your control pressure doesn't change when your helper revs it from idle, then there is a differential pressure problem within the head. Maybe something is gummed up in the fuel path to the injector ports?