My first bout with CIS

[Poor-sche Lover]

So, I've been voraciously reading as much as I can about the CIS system. I still don't quite get it, as I'm quite the newbie when it comes to any fuel injection. Anyway, I've got a bug I'm trying to figure out. Hopefully, someone can point me in the right direction. I will admit that I have not had the pressure tested, and the CIS tester will have to wait for now. I have also heeded the advice of everyone and have not starting replacing things randomly. I'm just trying to figure things out first. Here are my symptoms that I've noticed.

1. Sometimes, on a cold engine, when I try to start it, the car will start, but then immediately die. It will normally work the second time.

2. I've only had the car for about a month. It has always idled around 850 rpms. For a couple of days now, it has been idling around 1,100 rpms.

3. Just this evening, on a warm engine, I started it, and it struggled to idle at all. It was hanging around 550 rpms. I goosed the gas a couple of times, and got it to around 700, but it's still not right.

4. During the 1,100 idle time, it would slightly surge betwwen 1,000 and 1,100 at idle. This seemed to only happen when it was cold, but I did not get a chance to drive it more than a couple of miles during this time.

According to what I've read, this could be a simple vacuum leak (I'll check as soon as I can). It could be the auxiliary air valve. It could be the warm-up regulator. It could be a bad mixture. It could be any one of the "magical" 14 issues, it seems like. I'm looking for what to do first. My guess is the AAV, but I want to do this as economically as possible. Thanks for any input.

Alan
'82 Guards Red SC

[Oh Haha]

Start out with the simple stuff.
Vacuum leaks(already stated in your thread)
Fuel flow(filter changed recently?) If not, do you know when it was done last?
Spark(timing off or messed with at all?)

[boyt911sc]

Allan,

Have you air mixture set accordingly. Vacuum leak is not easy to locate but has to be fixed otherwise no CIS trouble shooting could make your car run better. For your cold starting problem, check your cold control fuel pressure. You need a CIS fuel pressure gauge kit to do this. Borrow one if you can find someone who has it. You can not do an effective trouble shooting without one. Try not to replace CIS component unless confirmed defective.

Tony

[oregonmon]

Ahhhh good luck. My mechanic told me (now that it's in the 30's here and surging idle) these systems will need to be adjusted to compensate for the ambient temps

[Sunroof]

A bunch of components make up the CIS, but usually the big culprit is the mixture setting. Its that little hole next to the fuel distributor. Do you have the adjustment tool? Ordinarily you use a sensor and the proper setting is in percentage, of which I do not know. When I first got my 73.5T with the first CIS, I would set and reset the mixture screw after short hauls, long hauls, idling, etc, to what I thought was perfect without the reading. One click at a time! I have always associated "surging" or a "searching idle" with a mixture adjustment issue. By the way...DO YOU HAVE A POP-OFF VALVE IN YOUR AIRBOX?! If you do not , INSTALL immediately. A backfire could blow up your airbox.

Right (clockwise) = rich
Left (counterclockwise) = lean

Fiddle with that for awhile before changing out warm-up regulator, cold start valve, thermotime switch, fuel pump, injectors, fuel accumulator, fuel hoses, vacuum hoses, etc...............................

Bob
1973.5T Sepia of course

[Scott R]

Cold control pressure is probably out of spec, don't do any "adjusting" until you can get a set of CIS gauges on it. While I don't doubt you could have vacuum leaks, the only thing that changed here is the ambient air temp, and thats when you need cold enrichment the most.

Secondly, you probably don't need mixture adjustments on a regular basis, I keep mine at the factory .08 setting and it's fine, starts in 30 deg the same as it does in 80 deg, and the AFM's are darn near perfect on the dyno, and on my gas analyzer.

[Ricks911s]

One problem with all threads herein is the piecemeal responses you'll get. The suggestions above are good ones. Don't get me wrong. But if you intend to TRULY tackle an idling issue, first commit a little time and patience . . and then some more time. CHECK YOUR TIMING and/or POINTS, in short your ignition, FIRST. Then move on to the CIS stuff . . .

I don't advocate the quick fix . . but it goes something like this. Get a 3mm allen wrench (has to be about 5 inches long to clear the air boot -- to the left -- and the fuel distributor -- to the right) and richen 1/16 of a turn at a time and repeat, i.e. follow Sunroofs advice. MAKE SURE YOU DO THIS WITH A WARM CAR. My understanding is that if you do it with a cold car you will almost always overadjust (make it too rich) because the system (when cold) is designed to have components (WUR, AAR, etc.) to adjust air flow to the CIS until the engine is up to temp.

For the record I think that's the LAST thing that should do. I'm trying to solve a "hunting idle" and I wish I hadn't adjusted mine before doing all of the other CIS due diligence. I experience the same symptoms as you and adjusting the idle/mixture DID NOT solve my problem.

I went through ignition, set timing, points (I have a '76), and set idle/mixture. Continued to have cold start problems. Logically moved onto CIS. Replaced a great many vacuum hoses. Idle went down CONSIDERABLY. Okay, so I thought I was running rich to account for vacuum leaks. Adjusted idle/fuel mixture on a cold car and idle went all over the board when I started the car the next day. Tested AAR (auxiliary air regulator) and it checked out okay. Finally, did CIS control pressure test, system test, etc., and found that it's likely my WUR (warm up regulator). I found a stripped hex nut on the back of my WUR (probably THE WORST place I've dealt with yet) and am taking my time to get the sucker off. Probably the last owner attempted to remove WUR to solve problem and it's why the car sat for the next 6 YEARS!

Either way, I hope you find a resolution that is equal to your confidence in the car. Some guys go overboard to feel 100% confident (replacing suspect parts or parts that weather with age). I think I'm an 80-90% confidence guy. Probably because I'm cheap and I like a little adventure. Oh wait . . . I just thought I'd forgotten my '73 VW Bug that went up in flames. Man . . . I didn't know an engine fire could be that big!!

[Scott R]

Originally Posted by Ricks911s

One problem with all threads herein is the piecemeal responses you'll get. The suggestions above are good ones. Don't get me wrong. But if you intend to TRULY tackle an idling issue, first commit a little time and patience . . and then some more time. CHECK YOUR TIMING and/or POINTS, in short your ignition, FIRST. Then move on to the CIS stuff . . .

I don't advocate the quick fix . . but it goes something like this. Get a 3mm allen wrench (has to be about 5 inches long to clear the air boot -- to the left -- and the fuel distributor -- to the right) and richen 1/16 of a turn at a time and repeat, i.e. follow Sunroofs advice. MAKE SURE YOU DO THIS WITH A WARM CAR. My understanding is that if you do it with a cold car you will almost always overadjust (make it too rich) because the system (when cold) is designed to have components (WUR, AAR, etc.) to adjust air flow to the CIS until the engine is up to temp.

For the record I think that's the LAST thing that should do. I'm trying to solve a "hunting idle" and I wish I hadn't adjusted mine before doing all of the other CIS due diligence. I experience the same symptoms as you and adjusting the idle/mixture DID NOT solve my problem.

I went through ignition, set timing, points (I have a '76), and set idle/mixture. Continued to have cold start problems. Logically moved onto CIS. Replaced a great many vacuum hoses. Idle went down CONSIDERABLY. Okay, so I thought I was running rich to account for vacuum leaks. Adjusted idle/fuel mixture on a cold car and idle went all over the board when I started the car the next day. Tested AAR (auxiliary air regulator) and it checked out okay. Finally, did CIS control pressure test, system test, etc., and found that it's likely my WUR (warm up regulator). I found a stripped hex nut on the back of my WUR (probably THE WORST place I've dealt with yet) and am taking my time to get the sucker off. Probably the last owner attempted to remove WUR to solve problem and it's why the car sat for the next 6 YEARS!

Either way, I hope you find a resolution that is equal to your confidence in the car. Some guys go overboard to feel 100% confident (replacing suspect parts or parts that weather with age). I think I'm an 80-90% confidence guy. Probably because I'm cheap and I like a little adventure. Oh wait . . . I just thought I'd forgotten my '73 VW Bug that went up in flames. Man . . . I didn't know an engine fire could be that big!!

Sage advice.

[Paulporsche]

You can get a CIS pressure gauge from JCWhitney for about $60. Knowing your fuel and, especially, your cold control pressures will probably go a long way towards sorting your problem.

Eliminating air leaks is important in getting the CIS to work correctly. As others have said, make sure your airbox is leak free, and install the popoff valve.

As Rick stated, always make sure ignition components are good first. Did you have a PPI? Do you know how old the cap, rotor, plugs and wires are?

[Poor-sche Lover]

Okay, I'm starting with vacuum leaks tonight. I agree that I don't want to play with anything trying to "cover up" the real problem. It has pretty much entered hibernation time anyway, so I'm not in a hurry. I do have the pop-off valve, by the way. I know from the previous owner that at about 6,000 miles ago, in 2001, the alternator was replaced, as was the original CDI box with a Permatune (the silver one). About 4,000 miles ago, in 2004, the ignition lock was replaced, as well as the coil, and the Permatune again. Finally, about 500 miles ago, last month, the starter was replaced just before I bought it. The records show that it has had some starting issues, but my isssue is not starting. It's idling (I assume). I will try to find out more information. We'll see how it goes. I'll check out JC Whitney. Thanks for the tip.

Alan
'82 Guards Red SC

[spuggy]

Once you've eliminated actual problems or issues, find any post by souk and follow the link in his signature to the CIS tuning threads.

[Ricks911s]

If/When you find and resolve the problem, please update me/us. I've kind of developed this interest in tracking which CIS problems seem to be more problematic than others. Right now my money is on Vacuum Leaks and WUR (warm up regulators) - in that order.

I echo what Spungy says with regard to Souk. You have to read his posts a couple times to get the gist of it (or at least I do). Best of luck.

[ianc]

+1 on Paulporsche's post. Your absolute first purchase should be the CIS pressure tester. Until you get one and know where your fuel pressures are at, everything else is just whistling in the dark. Good luck on it,

ianc

[Jim Williams]

Alan,

You'll find a lot of useful info on CIS on this website:

http://members.rennlist.com/jimwms/CIS/CIShome.html

Certain suggestions already listed bear repeating:

1. Make sure the mechanicals (compression, etc.) of the engine and the ignition system (timing, spark) are in good working order.
2. Verify the fuel pressures and fuel flow meet the specs for your engine.

Check the page on "Testing " to get an approximation on setting warm idle.

[psalt]

Allan,

Your symptoms are not uncommon for your model year, I've seen them many times in 20 years of working on CIS lambda cars, and they usually have nothing to do with the WUR or AAR. The CIS lambda cars have unique driveability issues and my advice is to read the Bosch manuals to get an understanding of how the system works. You usually can find a good compromise in basic adjustments to sort out the driveability issues. On an unknown car, I would do an oil change, valve adjustment and basic tune up with normal Bosch plugs before condeming any CIS components. Fortunately, you can make all the basic adjustments with an analog dwell meter and a timing light. In my experience, part swapping usually results in expensive failures.


This thread may be helpful:http://forums.pelicanparts.com/showthread.php?t=361652&highlight=lambda

Paul

[boyt911sc]

Originally Posted by psalt

Allan,

Your symptoms are not uncommon for your model year, I've seen them many times in 20 years of working on CIS lambda cars, and they usually have nothing to do with the WUR or AAR. The CIS lambda cars have unique driveability issues and my advice is to read the Bosch manuals to get an understanding of how the system works. You usually can find a good compromise in basic adjustments to sort out the driveability issues. On an unknown car, I would do an oil change, valve adjustment and basic tune up with normal Bosch plugs before condeming any CIS components. Fortunately, you can make all the basic adjustments with an analog dwell meter and a timing light. In my experience, part swapping usually results in expensive failures.
Paul

Paul,

Why do you need a dwell meter for this diagnostic test? Interested to know the logic of your suggestion and may help people to understand CIS better. Thanks.

Tony

[Poor-sche Lover]

Well, I didn't find any obvious vacuum leaks. John's CIS site is the very valuable. That's the first one I started reading. It's bookmarked. The JC Whitney tester has been ordered. Paul, can you explain a little bit more about the dwell meter? I can do a regular tune-up, right? Just plugs, wires, rotor, and cap?

[psalt]

Paul, can you explain a little bit more about the dwell meter?

Alan and Tony,

While not quite OBDII, CIS lambda will talk to you, if you listen. You really need to read a Bosch manual to understand the complexity of CIS lambda, information on how it all works together is thin on the ground. It is helpful to understand that the basic system components are set up way too lean and the lambda system brings the fuel curve back to "almost OK", with the main goals of meeting the specific emission tests of the day and converter life. This is why most advice and troubleshooting for K basic can be misleading. The frequency valve must be pulsing and the mixture set correctly or the engine will run like crap, even if you swap out the WUR, AAR, AAV, CSV. There are several throttle and temperature switches that were added on to correct the driveability of the engine after it could meet the emission tests. There is a test plug under the plastic cover on the left and if you hook it up to an analog dwell meter (green/white stripe wire) you can see the operation of the lambda system and properly diagnose and set the mixture. This is a big advantage over K basic. The meter should show a steady reading around 55 dwell during open loop, warm up, then start fluctuating between 40-55 when it goes closed loop. This is for a new engine with perfect compression and no vacuum leaks. As the engine wears and pulls less vacuum, most engines behave better with a richer setting toward 30-40 dwell. You make the adjustment with an allen wrench, with the final adjustment always clockwise toward rich. If you have never done this, make a tiny adjustment, remove the wrench and rev the engine and watch the meter. Understand you are only adjusting the open loop mixture (cold start, warmup and WOT). The system will correct the mixture back to stoich at idle and cruise, with little effect on emissions or economy. These cars also have a vacuum retard distributor which often causes the stall when starting. It's only purpose is to meet the curb idle test and overheat the engine at idle, so you can disconnect and plug the line, then reset the idle down to 950 with the large bypass screw. The US versions were detuned for 87 octane fuel, if you have better fuel you can advance the timing a few degrees. The 911 engine is knock limited, so you have to watch for pinging with high temperatures, especially if you have a lean running engine. When you check for vacuum leaks, the prime suspect is the orings on the injector sleeves. Porsche chose an inferior method to seal the injectors and all engines develop leaks here over time. Use an unlit propane torch and wiggle the injectors. The sleeves are staked in and often will pull out if you attempt to change the seals, remove the stakes first. Any vacuum leak with CIS results in less sensor plate deflection, shifting the fuel curve to the lean side.

Paul

[Paulporsche]

I recently disconnected and capped the vac retard on my dizzy. The engine has no Lambda or temp switches. Starting and idling were greatly improved.

[Sunroof]

I agree with everyone that has chimed in, but I guess I was lucky in that my idle issue was an adjustment of the mixture setting. It started when the car would die when exiting the highway and one day I just pulled over and re-set the mixture screw and amazingly the problem was resolved!! This was a Pelican head recommendation back in my early novice days!!

I did have issues with the WUR after that as well, since I had theoriginal (1973.5T) WUR on the car. A rebuilt unit made the car run even better. Over th e years I have been lucky so far, but I replaced every CIS component along the way in the restoration process, but the FUEL DISTRIBUTOR, which is now creating a hard start problem.

Not to take away from the central issue, as simplistic as CIS is claimed to be, so much depends on trial and error. In an older car its anyones guess what the culprit can be because a fresh component can take an older and worn part further out of balance. As you proceed to get the CIS right consider the other components down stream and that cold start valves, thermotime switches, injectors, WURs, hoses and even the fuel distributor may require replacment or testing sooner or later.

What a great board this is .....................

Bob
1st CIS