Porsche and CIS first timer

[christian977]

Hey All,

So about a year ago i bought my first Porsche 911, i bought not running, the engine and 'box was in pieces on many pallets when i purchased. Fortunately it was pretty much all there, not much has been missing...
The car has not been on the road since 2005, it was disassembled cause of head stud issues, and shifting issuing. The car itself is an 80 SC in really great shape, less than 160k kms, original GP white.

I am a heavy plant mechanic by trade, and have played with cars and machinery for many many years.

After more than a year, and ALOT of money spent! i have gone through the box, new syncro rings and various other required bits and pieces, and i have built the engine with ALOT of new parts, aftermarket high comp pistons, mild cams, heads were properly serviced, new valves, guides, springs, skimed etc etc...That was all pretty straightforward.

I am new to CIS, so did a bunch of research to get my head round it.

The WUR was in a box in pieces when i received the car, its a 069 version so that was rebuilt with a kit from Missing parts.

The fuel distributor, although assembled, when i looked inside the fuel outlets, and found one was missing a filter, so i disassebled and it was a good thing i did, as it was full of crud. I cleaned, re surfaced and re assembled both of these items with kit Missing parts (really good supplier).

I found the Airbox was cracked, so a genuine brand new one and new hoses was sourced

I disassembled and cleaned the throttle body.

I have tested all other CIS items as much as is possible in my home garage:

AAR checked and found working

AAV checked, and found defective, it would not hold a vacuum at all, the diafram must have been damaged, i got a second hand one, but this one does not seal very well... its installed, but for the moment i have that sealed off...

TTS switch tested as per instruction from this forum

Thermo vacuum switch tested found working.

New fuel pump has been fitted

New injection lines

New fuel lines in the engine bay.

The cold start injector was tested and working
The injectors were sonic cleaned, i had an aquantance pop test them, and he said they were OK, (but found out other wise during intial checks...) replaced with new...

I thought after all checks and rebuilding it would be easy to check pressures, check calibration of the FD and fire up the new engine.

Boy was i wrong...

Anyways after a BUNCH of playing with wiring i got things working, then i "tuned" everything CIS and got:
within 2% fuel at each injector at full fuel and half way (this was time consuming...)
Got Sytem pressure to 5bar
Got Cold Control pressure 2.1bar @ 25degree C
Got the WCP to 3.2 bar, (This was a difficult one to prove prior to starting the car... but once it was running it was verified)
Residual pressure was pathetic, so replaced accumulator, and now its within in spec, after 2 hours, there is still over 1.2 bar!

So i believe all is within spec.

Today I started the engine and ran it around 2000 Rpm, for initial run in, but had some issues with smoke from the heaterboxes as it warmed, (found an oil leak which was going onto exhaust) also, not sure, but the exhaust seemed HOT for a 10min run with no load and also some poping out exhaust on small decell

So, i am thinking it is lean???

Taking all of the above into account how do i richen it up??? I would prefer to start rich with a new engine.

[mikesarge]

Tony (aka boyt911sc) or AndrewCologne will likely chime in and be much more helpful here, but one thing that stands out to me:

Is this a USA or ROW car? If USA, do you have the stock lambda system? I believe the WUR for USA is not the 069, maybe 089?

If your lambda system (and associated Frequency valve (FV)) are not working correctly, you'll need to make some adjustments, either getting the FV set up, with the lambda ECU and O2 sensor, or changing other parts out.

[christian977]

Hi, Its a ROW car, so no lamda. 069 WUR is definatly original.

[Schulisco]

Wow! Congratulation for the effort without knowing the CIS on a 911 entirely!

Then CIS is all about fuel pressure, and some hints about the initial setup. You have to keep some steps in the right sequence.

1. First and foremost - check out the setup for the air flow sensor, especially the resting position of the disc in the cone. This must be set meticulously as Porsche specified. This setting has to be done at the very first step. A slightly change in up or down will have a huge impact on the mixture over the whole rpm range!
2. After that check the throttle valve if it's also adjusted following Porsche specs. Then close completely the idle screw and then turn it back / opens it by two revolutions. This is the basic setting for the idle screw.
3. Then close the CO screw completely / turn it clockwise until the end and turn it back 2 turns (to prevent flooding the engine!). Now shortcut electrically the fuel pump so that it pressurizes the fuel system and being ready to deliver fuel. The injection valves must not spray / give a squeaking noise adn flood the engine. Now turn the CO screw CCW until you hear the injectors valves start to spray fuel / give a squeaking noise. Turn now the CO screw half turn CW to stop spraying the injection vales. Shut down the electrical fuel pump shortcut/put back in the fp relay in the socket.
4. Now the basic setup is done and the engine should start with about 1300-1500rpm idle speed if everything else is working and in spec. Then warm the engine up / test drive it and urgently adjust the CO / idle speed with a gas tester as Porsche specified for your engine. (Which engine code? 930/10??). Always adjust the CO screw from lean to rich direction only because this is more precise with a trend to a more lean / lower end CO mixture overall.

I heavily recommend Klassik Automotive Training School Youtube Channel, Curt has made some of the very best CIS videos on the planet! https://bit.ly/3AMkoMk
https://www.klassikats.com/

If the exhaust gets hotter than expected - check the ignition timing, probably you're lacking of advance on idle and cruise. You'll find the correct values in the Porsche Workshop Manual, available on the web as PDF. Follow exactly the factory specs for your engine!

Thomas

[SkiVT]

In addition to Thomas comments, this is also useful to toy with lean/rich mixture assuming all else is in spec;

CIS Idle Speed and Mixture Setting Without an Analyzer

[boyt911sc]

Originally Posted by Schulisco

Wow! Congratulation for the effort without knowing the CIS on a 911 entirely!

......

3. Then close the CO screw completely / turn it clockwise until the end. Now shortcut electrically the fuel pump so that it pressurizes the fuel system and being ready to deliver fuel. The injection valves must not spray / give a squeaking noise adn flood the engine. Now turn the CO screw CCW until you hear the injectors valves start to spray fuel / give a squeaking noise. Turn now the CO screw half turn CW to stop spraying the injection vales. Shut down the electrical fuel pump shortcut/put back in the fp relay in the socket.
...........

Thomas,

Are you sure about the CLOCKWISE direction for setting the fuel mixture? If you fully turned the mixture screw CLOCKWISE all the way in and run the FP, you would be flooding the motor with raw fuel. Are you aware of this set-up? You have this thing backward. Adjusting the fuel mixture screw, CW is richer and CCW is leaner. If you don’t believe me, go to your garage and do this test to your motor and keep us posted.

Tony

[christian977]

thanks!! i plan to have the motor out again to adjust the valves (god only knows how you do that well in situ!!!) i will check sensor plate then. will have injectors out and do what is said with mixture.
Thanks again

[Schulisco]

Originally Posted by boyt911sc

Thomas,

Are you sure about the CLOCKWISE direction for setting the fuel mixture? If you fully turned the mixture screw CLOCKWISE all the way in and run the FP, you would be flooding the motor with raw fuel. Are you aware of this set-up? You have this thing backward. Adjusting the fuel mixture screw, CW is richer and CCW is leaner. If you don’t believe me, go to your garage and do this test to your motor and keep us posted.

Tony

Forgot to mention to turn the CO screw 2 revs backwards...I'll add this in my previous post. Thanks for the hint. It was late last night...

Thomas

[boyt911sc]

Originally Posted by christian977

.................(edit).............

So, i am thinking it is lean???

Taking all of the above into account how do i richen it up??? I would prefer to start rich with a new engine.

Christian,

For someone who claimed to be a CIS novice has been very impressive in his work. You got good attitude and would be a very good CIS troubleshooter soon. If I may add something, I suggest you perform a pressure test to locate those hard to find air leak/s in the system. A smoke generator with added air pressure (2 psi. or less) is a good way to locate these pesky air leaks.

Do not tinker with the mixture setting unless you have confirmed and verified the absence of unwanted air leak sources. Then proceed further. How did you test the AAV? A picture of your set up would be helpful. I am assuming you did it right because a lot of people failed to test it properly and causing to it to fail. Good job.

Tony

[Schulisco]

I always recommend to check the mixture with a lambda tool only. Everything else is poking around in the dark...and vacuum leaks can only be found for sure with a smoke generator. Brake cleaner, cigarette smoke and others are not reliable to identify all vacuum leaks, the CIS is one of most sensible fuel supplying systems for vacuum leaks you can ever imagine...

Thomas

[christian977]

Today did the initial mixture setting as per the above suggestion with turning the screws the correct way and ran the engine for another 10 minutes. I can smell it now, so yea, it makes me feel better. she has a total of 30minutes on it now, so tomorrow it is out again to adjust valves and look over it, and double check the sensor plate.
I am gunna get one of the Gunsons CO2 meters too so i can check it properly.

See the video, sounds nasty at idle, i love it!!!

https://www.youtube.com/watch?v=EUErhip0yms

Tony, although i am a new to CIS i am not new to mechanics at all... To be completely honest i have learnt 99% about CIS from this forum and alot of them being your posts!!

For the testing of the AAV i put my vacuum pump on the center port of the AAV, and then a hose with a ball valve on the outer port, closed the valve sucked the centerport down to 8"hg and opend the ball valve, the vacuum drops off pretty much instantly. I increased the vacuum in 2"hg increments and the one that is on there now gets to about 20 i takes about 5 seconds to loose vacuum. So therefore in my mind it would be an air leak, and therefore i have blanked ports of tbe valve.

After reading allot of the troubleshooting posts on CIS I was very very very cautious about air leaks in the intake system, i paid strict attention to all and ANYTHING that was suspect was replaced or reworked. i would be very very very surprised if there is any. I even reamed the throttle shaft holes and made bushings to ensure there was minimal clearance, therefore no leaks there, as mentioned new genuine porsche airbox was fitted too.

Thanks again to all the input you guys make to this board, i really is helpful for new enthusiasts like me!

[christian977]

I just located a regulator, and can make some smoke, so i will do the smoke test just to be sure, you guys got me thinkin now...

[Schulisco]

I also own a Gunson CO meter. They're precise enough for carburettors, but not for fuel injected cars...they got an inaccurance about 0,5vol%-1vol%. But you need a minimal 2vol% CO on a non catalytic ROW/euro spec 911 SC.
Indeed - for a very first approach it will be okay but you have to go to a certified gas tester...

Here's a video showing what kind of vacuum leaks on a CIS airbox we're talking...

https://youtu.be/H_SAcKXJlL0

And this is a video of KlassikATS showing how to troubleshoot a CIS 911:
https://youtu.be/slCzVrrST2Q I mentioned yesterday.

Thomas

[boyt911sc]

Originally Posted by Schulisco

Forgot to mention to turn the CO screw 2 revs backwards...I'll add this in my previous post. Thanks for the hint. It was late last night...

Thomas

Thomas,

I called your attention to your previous post because it was totally WRONG. Anyone in his right frame of mind should avoid such procedure. Turning the mixture screw 2 revolution backward won’t correct the problem you had created. Turning the fuel mixture screw fully in would cause havocs in your CIS. Hopefully nobody follows this poorly conceived instruction for the sake of safety.

I personally like you and you are very resourceful. But at some point, you seem to be reckless in your posts. Please review your post before some unsuspecting individual becomes the first victim. If you fully know and understand how the AFM unit operates, you would not think of doing it.

Let’s just call it a MISTAKE. We all make mistakes and I committed a lot too. If you are unaware the severity of this mistake, I failed miserably to get your attention. This is a Technical Forum and we could agree or disagree with someone and still be friends at the end of discussions.

Tony

[fanaudical]

One of the best things I've done for troubleshooting my CIS is to install a wideband AFR gauge. I have tried a couple different Gunson gas testers and they all provided different results. The wideband AFR gauge has helped me diagnose and fix:

- Erratic AFR at idle - pulsing injectors from bad fuel lines

- Erratic AFR at load - arcing in a distributor cap

- Running lean at load all of a sudden - vacuum leak

It's been useful. AFR ~13.8 = ~2% CO at idle...

[ahh911]

Originally Posted by boyt911sc

Thomas,

I called your attention to your previous post because it was totally WRONG. Anyone in his right frame of mind should avoid such procedure. Turning the mixture screw 2 revolution backward won’t correct the problem you had created. Turning the fuel mixture screw fully in would cause havocs in your CIS. Hopefully nobody follows this poorly conceived instruction for the sake of safety.

I personally like you and you are very resourceful. But at some point, you seem to be reckless in your posts. Please review your post before some unsuspecting individual becomes the first victim. If you fully know and understand how the AFM unit operates, you would not think of doing it.

Let’s just call it a MISTAKE. We all make mistakes and I committed a lot too. If you are unaware the severity of this mistake, I failed miserably to get your attention. This is a Technical Forum and we could agree or disagree with someone and still be friends at the end of discussions.

Tony

Tony, the instructions do not say to start the car, if you saw this are you still saying that turning the screw clockwise all the way in and then backing it out two turns with the engine not turning over but the fuel pump on and then adjusting the mixture screw till the threshold of injector spray with the sensor plate at rest position will be a fire hazard? If so, how do you suggest getting basic adjustment for a system that has been fully dismantled (no history of running and in pieces) and needs to be initialized to a base setting?

Phil


3. Then close the CO screw completely / turn it clockwise until the end and turn it back 2 turns (to prevent flooding the engine!). Now shortcut electrically the fuel pump so that it pressurizes the fuel system and being ready to deliver fuel. The injection valves must not spray / give a squeaking noise adn flood the engine. Now turn the CO screw CCW until you hear the injectors valves start to spray fuel / give a squeaking noise. Turn now the CO screw half turn CW to stop spraying the injection vales. Shut down the electrical fuel pump shortcut/put back in the fp relay in the socket.

[boyt911sc]

Originally Posted by ahh911

Tony, the instructions do not say to start the car, if you saw this are you still saying that turning the screw clockwise all the way in and then backing it out two turns with the engine not turning over but the fuel pump on and then adjusting the mixture screw till the threshold of injector spray with the sensor plate at rest position will be a fire hazard? If so, how do you suggest getting basic adjustment for a system that has been fully dismantled (no history of running and in pieces) and needs to be initialized to a base setting?

Phil


3. Then close the CO screw completely / turn it clockwise until the end and turn it back 2 turns (to prevent flooding the engine!). Now shortcut electrically the fuel pump so that it pressurizes the fuel system and being ready to deliver fuel. The injection valves must not spray / give a squeaking noise adn flood the engine. Now turn the CO screw CCW until you hear the injectors valves start to spray fuel / give a squeaking noise. Turn now the CO screw half turn CW to stop spraying the injection vales. Shut down the electrical fuel pump shortcut/put back in the fp relay in the socket.

Phil,

We are not talking a running motor just the FP. If you turned the mixture screw all the way in which is almost impossible to achieve without binding the Allen wrench but for the sake of discussion you completely turned the screw CW, you had caused the fuel distributor’s plunger to move upward a lot. So when you RUN the FP, what do you think will happen? The moment the FP starts to run, all six (6) cylinders would be getting a lot of unneeded raw fuel.

Instruction #3 has several ill conceived procedures but if the OP does not see the need to change or correct the blunders, so let it be. I could only hope that no one becomes an innocent victim.

You are a good troubleshooter, and should see the problem right away. If nobody finds anything wrong, ignore my warning and wish everybody well.



Tony

[boyt911sc]

Originally Posted by christian977

.....EDIT...........

Tony, although i am a new to CIS i am not new to mechanics at all... To be completely honest i have learnt 99% about CIS from this forum and alot of them being your posts!!

For the testing of the AAV i put my vacuum pump on the center port of the AAV, and then a hose with a ball valve on the outer port, closed the valve sucked the centerport down to 8"hg and opend the ball valve, the vacuum drops off pretty much instantly. I increased the vacuum in 2"hg increments and the one that is on there now gets to about 20 i takes about 5 seconds to loose vacuum. So therefore in my mind it would be an air leak, and therefore i have blanked ports of tbe valve.

After reading allot of the troubleshooting posts on CIS I was very very very cautious about air leaks in the intake system, i paid strict attention to all and ANYTHING that was suspect was replaced or reworked. i would be very very very surprised if there is any. I even reamed the throttle shaft holes and made bushings to ensure there was minimal clearance, therefore no leaks there, as mentioned new genuine porsche airbox was fitted too.

Thanks again to all the input you guys make to this board, i really is helpful for new enthusiasts like me!

Christian,

You were doing the test for the AAV incorrectly. I will find some pictures how the test is performed about the AAV test and evaluation. I had a suspicion that something was not RIGHT in your test procedure. Don’t feel bad because many of today’s experienced Porsche mechanics/shops don’t know how some of these CIS components are tested and evaluated. Most of the experienced CIS mechanics are retired by now and a dying breed.

This is a good time for the CIS enthusiasts to learn and pass it to the next generation the experience and knowledge about CIS in general. You are doing fine.

Tony

[ahh911]

Tony,
I did think of the screw binding if turning to the max/ or min as a negative and wonder if two turns back was enough to shut off the fuel flow with plate at rest, I assume some success was had or it wouldn't have been mentioned, but you seem in total disagreement and have seen plenty of these on your workbench so there may be variability and unknowns.

When I did this, the engine was removed for overhaul, took a 1/2 thereabouts inch plywood, drilled some injector holes into it and put the cis without shroud but with input air arms ziptied to plywood, attached some dollar store barbecue bottles with scale under injectors and slid the thing into the engine bay with something underneath to hold it up, some big storage container, then plugging in the fuel lines and measuring flow at different plate levels looking for uniformity with the plate slightly lifted then at a much more aggressive lift of the plate to simulate full throttle, thereabouts. Also checked drips with plate at rest position. Again, all while the engine was out for work over winter.


Tony, how do you go about it once it's in the car and you have no confidence that the setting is even remotely close?

Phil

Second pic I believe was testing the thermo time switch in preparation for the test with fuel delivery. Used a boroscope to look at the wonderful spray pattern coming out of csv, and timed it. no leaks.
p.s. did this with original injectors, then new injectors. I figured I'd purge the old crud out with the old injectors and see if the turn on threshold for new vs old injectors was the same, really saw little difference, but that's the way it goes, did not observe spray pattern as the injectors were new.

[christian977]

Hello Again All,

I had been busy with work, so the car went on the back burner for a while...

I am back on it at the moment and have it running and driving. I just passed its first roadworthy inspection in 17 years!!!!

I have done about 4 hours run time since the first run and oil change. it runs OK, however trying to run and hold low RPM whilst driving (below 2krpm) it gets very jerky, or starts to buck. I have to accelerate to stop the bucking. When i accelerate it pulls hard!!!!

Cams were reground by someone here in France, they are a little bigger than 964 cams (bit more lift and duration) with lobe separation of 108 degree. it idles lumpy, but never stalls. (see the vid above)

I have set the timing at 7degrees as it seemed better and less jerky at 7 degrees, i may try more soon, i just recieved a Classic Retro fit CDI+, so then i can adjust the total too.

% of Co2 is 3.5. I know that may be high, but she is still new...

Does anyone have any experience with bucking and what the cause of it can be????

Thanks
Christian