Porsche 911 CIS Resources
There is a lot of good documentation on Porsche 911 CIS but I had to hunt for it.
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I needed to learn as much as I could about CIS the same way I learned about rebuilding the engine itself. That is, get multiple books on the same topic to cross-check them and fill in any missing information from one book with the others. I also found some indispensable grass-roots CIS documentation through forum threads and independent websites. Here are the best resources I have found, both online and in print form:
Online Sources
These online sources explain high-level CIS function and troubleshooting topics in plain English, are not intimidating, and are very easy to follow:
Pelican Parts Forums, “CIS Troubleshooting for Dummies” thread by Tim Irwin
What I found most comforting about this thread is that it was written by an average person with a black 1983 911SC coupe (just like me 🙂 ) who was in my shoes only a few short years earlier. Meaning, he went through the entire learning process, figured the system out, and was generous enough to document it in an easy to follow way. Once I read through this thread, I literally thought to myself, “if he could do this, so could I”. It is more SC-focused, so it mainly covers CIS from 1978-1983.
Note: There is a metric ton of CIS info on the Pelican Parts 911 Technical Forum. I became very good at using the search function on that page to data-mine for good threads on specific topics. A supplemental search method is Googling, “Pelican Parts 911 CIS (insert keywords here)” and you will get different results than the search function within the forum.
Jim Williams CIS Primer:
Original URL: http://jimsbasementworkshop.com/CIS/CIShome.html
Backup URL: http://cis911primer.com/home.html
This site is fairly technical but still easy-to-follow and covers all Porsche 911 CIS from 1973-1983 (excluding Turbo applications, I think). It breaks down the evolution of CIS types and even goes into the details of the Lambda functions. The most valuable part of this site for me was the detailed descriptions of all the CIS subcomponent functions and how to test each one to verify its integrity. If you poke around you can find links to CIS service manual PDFs. 😉
Porsche Classic Genuine Parts Catalog (PET):
The 911SC CIS, especially the Lambda version from 1980-1983, is fairly complex with its numerous fuel and vacuum lines. Fortunately it was here that I found download-able, clean, exploded view diagrams of the fuel system labeled with current part numbers and parts quantities. I was able to print them out and stick them on my wall as a quick reference. Go to that link, scroll down to the Porsche Classic Genuine Parts Catalog and select your car’s model and year to download the PDF catalog for literally your entire car.
Print Books
These books get into all the deep-dive CIS function details, testing, and tuning specs for each subcomponent and the whole system:
Charles Probst – Bosch Fuel Injection & Engine Management
Robert Bentley Publishers, ISBN: 0837603005
In Porsche 911 CIS circles this is the most widely recommended text on the subject. Although it is not Porsche-specific it has comprehensive detail on the theory of engine management, continuous injection function, K-Lambda function, and troubleshooting and service from a general (not OE brand-specific) point of view. It covers the same amount of detail for pulsed-injection systems as well. It even has a small performance tuning section in the end but, as expected, there are no revelations in the CIS section.
Ben Watson – How to Tune & Modify Bosch Fuel Injection
MBI Publishing, ISBN: 0879385707
This book is also often recommended although not as much as the Probst book. It is similar in that it covers theory, troubleshooting, and service of CIS and other Bosch fuel systems but in less detail. However it does list specs for many popular European cars that run the various Bosch fuel systems.
The one nugget that I understood here better than in the Probst book was that on page 136 under “Trick of the Trade” it tells you that you can use the Lambda frequency valve dwell or duty cycle to directly tune the CO emissions without using a tailpipe tester. I had read in the forums that this was possible but it was nice to see the book confirm it and I then used it to tune my own system. Ill explain this topic later once I rebuild the system and tune it.
Porsche Factory Workshop Manuals (1972-1983)
These are the manuals that all factory-trained Porsche technicians used when these cars were new. They are very comprehensive and very expensive. They tell you exactly what Porsche special tools to use, where, and when. If you have a set of these, consider yourself lucky. Still, they are lacking some very fine details that the other CIS-specific books cover, so you can get by with the Bentley Service Manual and one or more of the Bosch fuel injection books.
Bentley Publishers – Porsche 911SC Service Manual 1978-1983
ISBN: 978-0837617053
This is the book that everyone who wrenches on their own 911SC typically has. It is a cheaper, condensed version of the factory service manuals. Some topics are covered in great detail and some are glossed over altogether. There is a lot of “install is the reverse of removal” going on and the occasional incorrect torque spec, but overall it is a good resource. The fuel system section is pretty good. Here you will find the most details for K-Lambda CIS, especially for the 1983 version. Lots of sub-component troubleshooting and tuning specs.
Professional Bosch/Porsche Technician Service Manuals
Various Bosch K-Jetronic Workshop and Technical Instruction Manuals also exist that are Porsche-specific. They were probably Bosch/Porsche technician training materials for when CIS was new. They are fairly concise and mainly diagnosis and repair focused. These are also a huge help with the Porsche specific system requirements and repair. I don’t know if they were ever available to the public but you can occasionally find old hard copies on eBay or Porsche classified forums.
Believe it or not but there is still more info out there besides what I have listed but I felt that this was probably enough for me to get the job done.
Armed with all this info, I deep dove and read as much as I could until it started to make sense. To this day I don’t claim to understand all of it, but at some point I had enough high-level knowledge to give me the confidence to start the teardown process of the CIS rebuild.
Next time Ill discuss the details of the metal airbox I chose.
References:
See all book and website info above.