'Hot Rod' CIS & a few other upgrades=Happy SC

[KyMitch]

I know this isn't anything new, and I'm no pioneer to this. It seems there's alot of folks having trouble with their CIS so I thought I'd post this option that's working great for me. I googled Simplified CIS a few times which brought me right back to pelican and this is pretty much what I gathered from several different threads.. My opinion of CIS is a mechanical injection system, with the lambda emission system piggy backed on to it.
I've had the 3.0 out of my 83 SC this year for a reseal and such. It didn't run to bad before, but there definitely was room for improvement. So I sent my distributor off to Barry Hershon for a rebuild & recurve, installed MSD ignition, an sent my WUR off to Brian Leask for a rebuild and made adjustable. I ordered everything I could think of from our host to reseal the CIS, from the intake runner gaskets to the throttle body O-ring and everything in between... And an LM2 AFR meter.
Here's the cool part Then I stripped every thing that has to do with the Lambda off the CIS and plugged it all off. I'm not sure if my lambda system was even complete to begin with..? I consider myself a semi-purist, so it did kinda hurt, kinda lol. So what I've ended up with is ONE vacuum line from the throttle body to the WUR (original) and ONE electrical plug, to the WUR (original). I kept the two one inch hoses running from the crank case vent to the oil tank and back to the CIS boot original as well.
I've aggressively ran about 3 tanks thru it so far and I couldn't be happier. At first start (cold control pressure) is a little choppy at idle, but it's definitely drivable. I think I can adjust some of that out yet. After the WUR warms up (warm control pressure) it's ALL GOOD! AFR's are great, Idles at 900 rpm like a sewing machine at 14.7, I can idle across the RR tracks in 2nd gear below 900 rpm and get back on the gas without the first cough, pop, burp, or hiccup. And mid-range thru top end are a blast, great pull all the way.
Hats off to the Pro's Barry and Brian for fixing up my equipment for me. All I did was a little homework, and throw parts at it. Set the timing and control pressures.
Hope this helps you semi-purist, hot roddin heathens that don't mind ditchin all that stuff for an easily tuned CIS. Thanks for reading, good luck and happy wrenching!
P.S. My state does not require smog/emissions tests
Mitch

[KyMitch]

I got excited and didn't take pics before I put the motor back in..

[tirwin]

Good job!

After 30+ years these cars have suspect components. Best thing you can do is really just pull the motor and go through the system completely.

Read up on the posts by psalt. These CIS engines tend to the lean side and if emissions is not something you have to worry about they are much happier being a little on the rich side. My car is night and day difference from when I first bought it.

Now go drive it like you stole it!

[KyMitch]

Thanks Tim!
Thats exactly right, suspect components, and suspect grubby little fingers from too many different peoples over the years

[jjeffries]

I have an 82 whose motor I rebuilt last year...car came to me with the engine apart and is my first 911. I too made sure the CIS system was nice and tight, and was running it with the Lamda but at my first post-rebuild valve adjustment (@1200 miles) found the plug tips were bright white; the idle was a little uneven and it ran just a hair fluffy at higher RPMs. I fattened up the mixture a hair, then installed an AEM AFR gauge, using the 0.5V output of the gauge to send a signal to the Lamda. box. The car was not happy with this, so until I could add a second bung on my cat delete pipe, I unplugged the Lamda. The car ran even better...made me realize it wasn't quite right before, but now it was sweet. The gauge shows mid 13's for AFR under moderate throttle, which I wondered might be a bit too rich (it would be, I believe, for a Motronic 3.2). But then I did another valve clearance check a further1200 miles after the first, which obviously entailed another removal of the plugs; they were just the loveliest light grey/brown color. For me, this says the engine is happy with this mixture. When I did this second valve clearance check, I also added the second bung so I could reconnect the Lamda with its own O2 sensor and standard wiring, not through the AEM gauge. It still didn't like it, so I've disconnected it (again) and will leave it thus.
Did you replace your fuel hoses? I did with beautiful new assemblies from Len Cummings aka BoxsterGT....peace of mind. Best regards, John in CT.

[KyMitch]

jjeffries, good to hear. Mine is hanging out in the 13's while throttled as well, I don't think it hurts anything at all.
No I haven't done any fuel lines yet, that sounds like a good winter project, something light and simple for a change. I've heard of someone that makes lines that screw onto the old, so you use the old to pull the new in. Is that Len Cummings lines?

[boyt911sc]

KyMitch,

Good to hear to that your CIS engine is running well. But I have a couple of questions if you care to share with us. First, do you still have the WUR-090? This is the stock OEM WUR for your engine. Do you know the value of the heater resistance (Ohms) for the WUR when the engine is cold? Thanks.

Tony

[KyMitch]

Hello Tony,
Yes I still have the 090. My meter has a few different ohm settings, 200k, 20k, & 2k. Not sure which to use, been a while since I ohm'd out something like this. Anyhow, at the 2k, I got .041. Is that what we're looking for? Thanks, Mitch

[boyt911sc]

Originally Posted by KyMitch

Hello Tony,
Yes I still have the 090. My meter has a few different ohm settings, 200k, 20k, & 2k. Not sure which to use, been a while since I ohm'd out something like this. Anyhow, at the 2k, I got .041. Is that what we're looking for? Thanks, Mitch

Mitch,

Set your tester for resistance (Omega symbol). The resistance you are measuring is less than 30 Ohms and set it at the lowest range. You need to remove the electrical plug to the WUR to do the measurement. Thanks.

Tony

[KyMitch]

Ok, I guess that would be the 200 mark on mine. Yes the wur is unplugged and cold, hasn't been energized in 24 hrs. My reading was 42.2.

[boyt911sc]

Mitch,

Never seen a WUR-090 with that high resistance (Ohms). The average resistance is between 25~27 Ohms for this type of WUR.





I am not familiar with your multi-tester. This is the first time I've encountered a WUR-090 with such a high resistance value.

Tony

[KyMitch]

Allrighty then. I know digital meters can read high if the batterys are low. I also have a craftsman just like yours, I'll get some new batts for it too, and retest and report back tomorrow.

[tirwin]

Originally Posted by KyMitch

Ok, I guess that would be the 200 mark on mine. Yes the wur is unplugged and cold, hasn't been energized in 24 hrs. My reading was 42.2.

Why is your black wire plugged into the 10A port? Just for giggles, move it to the COM port and repeat the measurement.

You're not measuring amperage for this test so I don't think it should be in that port.

[KyMitch]

Actually I tried that, got the same reading. I guess it doesn't make a difference on resistance. Thanks tho!

[KyMitch]

Tomorrow I'm gonna put a fresh battery in my craftsman, and I'll move the black plug to com and retest. I'm a little rusty on electrical testing, I'll get it figured out tho!

[boyt911sc]

Originally Posted by KyMitch

Allrighty then. I know digital meters can read high if the batterys are low. I also have a craftsman just like yours, I'll get some new batts for it too, and retest and report back tomorrow.

Mitch,

Take a look at the probe connections for my multi-tester and compare yours. Use the center connection instead of using the one on the left side of the tester. You will probably get the right reading next time. Keep us posted.

Tony

[KyMitch]

I'm on it, will be tomorrow anyway. I'm pullin the graveyard shift this weekend...
So what happens if my resistance is off? I guess I didn't read up on it enough. Is that what my adjustment hardware installed by Brian alters? I've just been going by my cold & warm control pressures and my afr's. And probably haven't paid enough attention to the cold adjustments..

[RarlyL8]

Your WUR is adjustable now, you can manually dial in the pressures your engine responds best to. Factory specs are only a starting point; your engine and components are 30 years old so don't expect factory (WUR) specs to be optimal unless everything else (FD, accumulator, pump, CSI, etc) is brand new. An AFR meter and pressure gages are all you need to dial it in perfect. If the engine starts up a bit sluggish tweak the pressure 2 pounds lower then try another cold start. Track the pressures and corresponding AFRs to dial it in more quickly. Once you get the cold pressure dialed in measure the time it takes to reach full warm pressure while noting corresponding AFRs and how the engine is running. Starting point and ramp time are temperature dependent so best to do all the tweaking at a similar temperature.

[jjeffries]

Mitch, yes, Len Cummings' fuel lines are the ones you've read about on PP threads. You use the supplied female/female coupler and pull them through the tunnel, from the rear to the front. Easier with engine/trans out but not mandatory. His lines as are per stock BUT with unions added where the hard polyamid plastic tunnel hoses meet the rubber extensions at the front (up near the steering rack). This means if/when the rubber hoses need replacement (20 years from now?), you'll be able to replace them only....and leave the (last forever) polyamid tunnel lines alone. Hardware is all very nice, German, white zinc plated (I think). John

[KyMitch]

John- Ok cool, thanks for the info, and another winter project lol. Sounds like some quality material!
Brian- Yeah that was the direction I was headed. Tony has me curious about the resistance so I might as well learn about that while I'm at it. I need to brush up on my electrical expertise, obviously lol. My idle at cold start may have been compromised some when I had Barry ditch the vacuum advance as well. I appreciate you jumping in, thanks for the advise!