How many different CMA/MFI manuals are there?

[David E. Clark]

How many different Check Measure Adjust Manuals are there?

The Mechanical Fuel Injection, Check Measure Adjust manual on the Pelican site is number 4532.20. It is 47 pages long.

I have another original factory manual number 4532.21. It is 52 pages long. The major difference is that 4532.21 contains a six page section called "Storage of Fuel Injection Pumps - Porsche 911 T, E, S Part Identifier 250 10" There are also minor differences in the main text. For example, 4532.21 suggests using Chemtool B 12 cleaning fluid for the air bypass bores (pages 7 & 23), 4532.20 doesn't.

I know that this is a bit of an esoteric question, but does anyone know how many different CMA manuals there are and what the differences are?

[David E. Clark]

Another big difference is that 4532.20 recommends using 91 octane fuel on 1972 and later cars and 4532.21 recommends using 87 octane fuel.

4532.20:

4532.21:

[304065]

There's only one, but there are a couple of scans floating around.

One of the scans is very fuzzy, it is the original we've been using for years. The one available in Derek Murray's signature is a new scan of an original manual and is nice and bright.

The storage information and some of the MFI repair information is often tacked onto the end of the core manual in some scans.

The information remains the same, however. Do you know the sequence by heart yet?

Any
Competent
Porsche
Driver
Tracks
Faster
If
Brakes
Come
Smoothly

Translates to:

Air Filter
Compression
Plugs
Dwell
Timing
Fuel pressure
Injectors
Belt (MFI pump timing)
Correlation
Smog

[David E. Clark]

John,

There are at least two. I have an original factory manual number 4532.21. It is 52 pages long (factory numbered pages). You'll notice that it has the next number in the sequence 4532.21 vs. 4532.20. It is also 5 pages longer than the one scanned by Derek Murray. Mechanical Fuel Injection, Check Measure Adjust. The newer manual (#21) changes the fuel octane requirement from 91 to 87 and has a section about cleaning the air by-pass bores that the older manual (#20) does not.

I don't mean to argue with you, but I would like to know if there are other "official" versions of this manual and what changes they contain.

Thanks for all your great posts here and if you could contribute to the Ultimate MFI Resources Thread or the MFI Message Board Index it would really help all us MFI guys (and gals) out.

[Grady Clay]

David,

I too have both 4532.20 and 4532.21. I recall there being a CMA version that didn’t cover the 2.4 (only 2.0 & 2.2) but I don’t have a copy (I probably tossed it when the 47 page 4532.20 was published.

CMA is currently listed in the Dec. ’05 PCNA Retail Price List:
WKD453220 BROCHURE 5.20
WKD453221 BROCHURE 5.20


There is a “document” that pre-dates the CMA. It is a set of “speaker’s notes” that accompanied a slide presentation about MFI at the Bosche/P+A school. It isn’t particularly useful as a CMA document but more to remind attendees of the material covered. It doesn’t have a number but its title is: ”Adjustment of Mechanical Fuel Injection; P+A Dealer Level Training.” I’ll speculate it was first used in ’68 and this version was from the early ‘70s when the importer became the P+A division of VoA.

Best,
Grady