Good luck. I don't know if it is different for the turbo, but I think .028 is usually used for plug gaps w/ the stock CD.

Some things to keep in mind:

This is a Bosch system used by many European cars, incl Porsche, Mercedes and BMW.

The design is about 33 yr old and was the best thing around then for reliability, driveability, emissions and economy

Your system is about 28 yr old.

The components can be affected by fuel contamination, dirt, varnish, etc.

Quite often problems attributed to CIS are actually ignition related.

When you say ignition related how do you mean? In what way?
Also, I just needed to vent there for a min.

I can't dissagree that for the 930 Porsche held on to the CIS about 10 years too long. But that's what we've got for now.

Need to add - I checked the clearance and function of the air metering plate last Sunday when the WUR was swapped out. It was perfectly aligned, sealed when off throttle and functioned properly.

Here's a link to some information on CIS for the 911:

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

It has a fair bit of info.

JR

Thanks Java,
Actually I spent a fair amount of time last nite reading alot of that info. I think we may have found a break in this problem, I will post results tomorrow.

An interesting comment, because it was Porsche who chose to use the CIS system on their premier model for all those years. I don't think they were wrong; a well-tuned CIS system delivers good starting, good power and good throttle response. Like me, there are many guys out there driving their CIS cars every day. Take a modern car and when you step on the throttle it’s like there’s a sponge ball under your foot. CIS died because of emissions and fuel economy; not necessarily performance.

CIS was good in its day, but its day was over the moment the Carrera came out with Motronic EFI. Having CIS on a 1994 Turbo 3.6 is an abomination.

Couldn't agree more. A good efi system is far superior to even a properly tuned CIS system--better mileage, throttle response, certainly much more tuneable for high horsepower apps.

To charge almost 100 large for a "flagship" car with CIS in 1994 was flat-out ridiculous.

Problem solved, the previous owner of the motor (A Porscha shop owner) removed the 3/4 hose from the AAV to the IC and installed a nice looking filter there opening up a huge intake leak. After removing the filter and reinstalling the hose, cranking issue solved. Now after we get the CO set, this conversion should be complete.
Thanks for everyones help.
Mark

Tripster,

I hope that does it.

Once again a vacuum/air leak causes a CIS problem, and in this instance, a leak caused by a PO's modification gone awry, not the system as designed.

I'm not trying to be unkind here, because I can understand your frustration, but look how much venting was done (as well as by others on the BB in various other threads) about the POS CIS, when the system in question didn't even include all the components, and had an unauthorized mod causing the problem to boot!

I think the "venting" involved was not claiming that CIS can't work. It was claiming that it doesn't work as well as efi, and that what was acceptable in the 70's to mid 80's was not acceptable thereafter, given the state of technology available in injection.

Can't argue that the newer systems aren't better, just that it was the best available then and, considering the age of the components, still functions well today. In fact, if his start/warmup/run problem is solved, it is w/ a system missing some of its components!

Did not mean to offend anyone during my venting time. I am pretty new to the Porscha world. I guess what I was saying is that the CIS was used a little to long in my own opinion. Even after they came out with a better system, they continued to use the CIS for several years. Just wright me off as being young and learning in this new quest of Porsche.
If you read back in this thread you will see I said if I had or could find the info (manuals) on how this system worked, I would think I could have solved the problem. Give me time Paul,,, I will be worthy.
And thats for all you time and input in this thread, always a plessure to get input and feedback.

No offense taken. It's just that the CIS systems have many places where an owner can screw them up and then blame the system. Like your experience.

Many racers swear by Webers which is even more ancient technology. For everyday driving there's nothing wrong with a well sorted out CIS system. All I was trying to say is that, on their most expensive model, Porsche could have easily switched to an EFI system. Why didn't they?

Thanks for the understanding. That was my question, why not use they technology they spent allot of time and money come up with?
Come on guy's, I am on a pretty good high today, nothing is going to get me down. She is TURBO'Dhttp://forums.pelicanparts.com/uploa...1142530135.jpg

CIS, EFI, Webers, etc - whenever it doesn't work you get frustrated. It's easy to pick on CIS now that EFI has progressed to its present state.
I personally like the component structure and relative simplicity of CIS. As you know, my system is stripped and works well for what it is. When the day comes that I can justify throwing several thousand dollars at an EFI system you will no doubt hear me scream about the evils of computers. It's the nature of the beast.

Because Porsche was in financial hot water in the early 90's, and didn't want to spend the money to develop a brand new black box for its relatively low volume turbos. By that time, technology was such that efi was clearly a superior technology, and Porsche should have used it in its flagship car.

It remedied that error in the 993tt.

The long version of why the last of the 930s and the 964-based turbos continued to use CIS comes down to money, in a roundabout sort of way. Porsche had started planning a new car in 1982. In 1984, design began in earnest for a high tech replacement for the 930. At the end of 1988, not far from the intended debut of the new car (scheduled for shortly after the introduction of the 964 Carrera 2,) it was canceled. The engineers took a look at what they had laying around that could be used in a stop gap turbo based on the new bodyshell and decided to use a cat-equipped version of the optional (in Europe only) Sportkit" engine, which made 330 hp. They were looking for an output of 300 hp, after fitting the cat. When they tried the first examples and got 320 hp, they didn't look any further.

The late 80's and early 90's were pretty lean times for Porsche, so it's a little surprising the cars got any development money at all.


JR

Hey Tripster,

Don't worry--no offence was intended or taken. And don't be concerned about being "worthy". This board is an extremely valuable tool for working out problems just like the one you just had. I've yet to meet anyone who knows everything. It's the collective effort of this group that makes it so good.

And don't forget--you solved the problem by consulting the PO, not through any suggested remedy from the board!

Glad your problem is fixed, and was done so easily and cheaply.

Enjoy your car!

Actually I have not talk with the Previous owner since buying the engine. He did not send everything with the motor as agreed when we made the deal which got us crossed up. The problem was seen by a picture posted of the motor on another site.
And thanks again for not being offended, I value the help and opinions of the board.http://forums.pelicanparts.com/uploa...1142603685.jpg