MPS, Rebuilding the MPS Options

[Ron914]

Hello to all who have helped me with this project . @emerygt350 ,@TJB/914, @Superhawk996 , @ChrisFoley , @rjames , @MDTerp
I am in the middle of rebuilding my MPS and have a couple of comments and questions .
First when I opened up the unit I found the most difficult job was removing the rivets holding the two halves together.
When I removed the retainer plate to take out the old diaphragm it was in two pieces .

I needed to take two measurements since I was replacing the stop screw , I needed to measure the the stop screw protrusion into the housing . The instruction sheet sent to me by a member had the measurements he must have made when rebuilding his MPS . His stop screw protrusion was 1.97mm and mine only measured 1.72mm.
His inner/outer screw assembly depth in the old diaphragm measured 6.51mm .
Here's one of my questions ?
when I measured mine I got two measurements depth to inner/outer screw assembly was 4.03
and depth to the washer outside the inner/outer screw assembly was 5.46mm.
Again there is a difference and since mine was never accessed before (epoxy over screw was not disturbed) is the difference in measurements ok and which measurement should I use I will try to attach a photo or two to help with my question.
this one .

I have not touched either of these measurements yet and awaiting any help/comments.
I think it's this one to the washer on diaphragm .

[Ron914]

Hello to all that have been helping me getting my 914 up and running so I can finally enjoy driving it and passing my CA smog test , @emerygt350 , @Superhawk996

Since some time as passed since I last posted on this so I will recap my situation.

I bought my car 1976 2.0L D-Jet in March /2022 . The car had the motor removed and disassembled by the previous owner when I purchased it . It has been both a fun and frustrating experience getting to where I am now . This was my first 914 and I welcomed the challenge as Covid was still going on and I needed something to occupy my time and I always wanted one .

I wasn't confident with assembling the lower end of the motor so I had Brothers in Ontario put it together for me and I worked on putting the rest together and installing it in the car .
I have no previous owner information to add and have no history of the car .
I purchased a new flywheel / Sachs clutch and AA big bore pistons from George @ European Motor in Hawthorne . The motor is now a 2056 . I have no information on which cam was used as it came with the box of parts that I got with the car ( I believe it to be stock) . I did have Brothers install chrome moly connecting rods and George did balance the new flywheel
Renato at Brothers bench tested the motor and broke in with a carburetor set up since he did not do fuel injection .
When I first installed the motor it started right up but always had a high idle due to a vacuum leak somewhere .
I replaced all vacuum lines and installed all new gaskets before starting the motor . The high idle prevented me from passing a smog test so I have ben chasing that issue for over a year .

I have since worked on the decel valve ( I believe it was adjusted wrong) , had Mark K rebuild my throttle body , and purchased a CF MPS rebuild from a member here on the site . Car was idling good and I drove it 10-15 miles before removing the MPS to rebuild it . I rebuilt my MPS because it leaked and would not hold vacuum for very long and was told I might as well replace the diaphragm with Chris's rebuild kit since I will need to properly tune my MPS because of the 2056 motor upgrade .This was in April and I was looking forward to attending my first WCR in June and drive my car but something went south from that point . After replacing the diaphragm I reinstalled it and when I started the car, it went from running good to running poorly and shaking as if it was missing a cylinder or two.
I now have had time to get back to the car and have some questions and findings too report
printed out PB Anders trouble shooting D-Jet pages from the tech notes on this site and pulled out my multi meter to make some checks . I have made some progress and I have the following values to report as the car will now start up (no shaking ) but it will just die after about 5-10 minutes of running .

I checked TSI ambient air sensor between ECU plug terminals 1 & 13 = 295 ohms (seems ok)
I checked the four FI's and had
Cyl1- ter. 3 to ground = 3.1 ohms , Cyl. 2 ter. 4 to ground 3.2 ohms , Cyl. 3 ter. 5 to ground 3.2 ohms and Cyl 4 ter. 6 to ground 3.1 ohms

MPS terminals 7 & 15 = 94.4 ohms ( no continuity to MPS case for all 4 terminals ) & 8-10=346.4 ohms (seems good)

Terminal 11 to ground 0.6 ohms (?)

Triger contacts 12 & 21 and 12& 22 switching ok when engine cranked over

Terminals 16/24 to ground 12.34VDC ( voltage measured at the battery 12.84 VDC)

TS2 CHT -@68F 5.3K ohms
@79F 3.6K ohms
once the CHT temp gauge (Dakota digital) reaches 100-104F the car just shuts off and does not want to restart , @ this time my readings between terminal 23 & ground reads
74.1 ohms., once car cools down it will start again.

I have re-terminated several of the D-jet connections which did make a difference .

I have a remanufactured ECU in my car with the following information on it
ECU P 039 906 021AV 10/75
220 006 052 095

MPS 0280 100 043/ 039 906 051/VW

Decel valve 280 160 001 / 311 133 030 527

Distributor 039 905 205 A VW

CHT is old ,looks original , assuming a 00 280 130 012 . I also have a new one I purchased from 914 Rubber (not installed )

My motor number is GC004876 , Trans HA08105

My suspicion is the CHT is bad but I am not sure . When I first started looking in the box of parts that came with the car there was a funky looking homemade resistor that was unusable so I assumed I need to replace its and purchased one from AutoAtlanta but have since been told remove it as the as only used on a 70-73 1.7 so I took it out of the CHT circuit .
Since I have read a few posts suggesting to install a potentiometer inline ,my question is should I do this to keep my CHT ohm reading higher when the car warms up .

I installed a Vacuum gauge ,Dakota digital CHT and still need a bung installed in my muffler to complete the AFR meter I installed also .
When I first start the car my Plenum vacuum is about 20inHG but once car motor is warm the vacuum falls off before the motor dies .

When I first start the motor the AAR brings the idle up to about 1400 rpm ( normal) once it closes idle is still a bit above 1000 rpm but I can use the idle sure on TB to lower it . I have not yet tried to drive the car .

Any suggestions ? I do have a local member that has offered to give me a hand with my problem (Bob D)