Dead ECU?

[raygreenwood]

Tram....No one is saying the books are wrong at all.


What is fact...is that the books say exactly what was known in about 1972 for D-jet.....which was that if you keep everything exactly stock and factory spec and bring it right back to"book" settings....and replace the part(s) that are bad with a new one of exact factory spec.....of course it will run.

The problem is this...and in a different thread Jake Raby quoted it quite eloquently about 10 days ago....stock is dead. There is no such thing as stock anymore. I fully agree.
Its been ages since you could exactly get something back to stock. NOS parts are drying up, heads are on their 3rd, 4th and 5th rebuilds. Piston and crank and cam specs are not what they were.

This changes everything.
You want to play with bone, NOSstock and nothing else and you have an endless supply of parts with a factory fresh harness...go for it. I stopped running around gnashing my teeth about 20 years ago.....looking for the dead on bone stock part # of MPS to match each ECU for my 411's and 412's.

It may seem easy to find NOS parts now...simply because we have teh internet. Not having that 20+ years ago.....there were no new parts...and zilch for interchange information.

The only way I even learned of interchanges within MPS's wre this....in order:

(1) A few knowledgable dealer reps at some of the last local VW dealers around me when I was in high school. They were the first to tell me of interchanges and alternate calibrations within part #'s of MPS's. They were the first to describe the "paint marks" on alternate calibrations. They could never produce a list or micro-fiche for me. They simply said....and this was 1978-1980....that when a customer brought in a D-jet injected car that would not claibrate and run properly when all else was well....they would call it in to Germany and an alternate paint code MPS would be shipped (typically 3-weeks).
These were the first people to twig me to the fact that a single adjustment MPS for any year of type 3 were functionally identical. They are just produced (in minor detail only)...slightly differently.

The early slotted screwdriver type one like 311 906 051 B (0 280 100 001)...were prone to leakage around the 0-ring on the adjusting screw. The design variation that fixed that is what you find on the 311 906 051 E (same unit as both 0280 100 106 and 0280 100 116....all the same exact unit). The later allen wrench design...is the same exact unit save for the allen wrench adjsuter and the way the aneroid chamber mounts. It was less prone to vacuum leakage....and much harder to tamper with by owners.

(2) Oddly enough...the second hint of cross-matchability...as I noted...was in Muirs book. Other than that list, John Muirs book is a decoration.

(3) In those days....I had rows of type 3's and type 4's in my local junkyard. No one wanted them. I bought all of my MPS's to experiemnt with...out of a 55 gallon drum of them...for $5 each.
Not knowing they were expensive parts...because they were generally unavailable except by sepcial order....I bought buckets of MPS and dissected many of them.....and drove on most of them....and adjusted all of them. It took me damn near 5 years of playing just to figure out exactly how the late model diaphram MPS actually works inside...because for so long I was afraid of destroying them by taking them too far apart.

After I found quite a few that had gotten wet and were obviously dead.....I was no longer afraid to take them apart.

From this point on...It was easy to figure out why these are recalibrate-able and are easily cross matched..as long as you generally stay within the type...diaphram or non-diaphram....that your car uses.

What I found is that with calibration...you did not have to stay bone stock (except cam timing and valve overlap....because the MPS's can be adjusted. There are limits. The earlier they are...the more limited their adjusting range is.....which is how I found out that you can also use a diaphram type on a non-diaphram model....you just cannot replace the function of the pressure switch with it.


Again...notsaying that teh factory method and staying exactly to it ...does not work. I have never said that. What I am saying...is that you are in know way limited to the factory parts list....once you learn how these parts work. RAy

[emitor81]

It must not have been the original pressure sensor. The epoxy on the Allen slot was in tact and just now is messed with.
I was hesitant but I messed with it. I marked the original point and kept track of direction and amount of turns. I first got it to run and keep running by pouring fuel in. It stayed half on then I made my adjustment. It didn't do much at 1/4 then I kept going and at full turn ccw it smoothed out.

Thank you all for any input provided. I've learned heaps about this system. I'm not done with it or with you guys but I think maybe this thread has been answered and done.

So I thought it was the computer but it turned out to be a wire to one of the heat sensors that kept the comp from sending juice to the injectors. (check the comp wiring for continuity). Then I had a lean condition which turned out to be because of the pressure sensor. Still not sure if it's the one my car should have but the adjustment (rich ccw) has it running.

[Tram]

[raygreenwood]

Amazing....it is so rarely the ECU. Excellent! Ray