MPS Mapping, How and what info do you want? Options

[rjames]

Yeah, I acquired 2nd hand both an MPS and ECU rebuilt by FI Corp, and neither of them worked. The MPS still had what looked to be the original diaphragm, but it was cracked. Not sure exactly what they rebuilt on it. (IMG:style_emoticons/default/rolleyes.gif)

[FlacaProductions]

Hey Robert - thanks for this. Hopefully it provides some more data points. Feel free to open it up and see what you see...why quit now?!

I'm still curious as to why it ran "fine" (or at least allowed it run adequately) until i switched to the 123 where it completely incapacitated the 2.0....

[emerygt350]

I think there is magic involved....

[brant]

ron is a local 914 guy...
had an LE (74) at one time still FId
ran so-so...

he found an NOS brand new MPS for his year
bought it... showed me..

the car ran on the old one.
put the brand new one in that had not been rebuilt... was still in the box, unmolested...

it wouldn't start..

put the old one back in and it started right up.

sounds similar to your situation.

[rjames]

Finally got around to opening up @FlacaProductions MPS.


It ended up having the 2.0 spacer.


This thing was crusty though.


Also, On the 3 rebuilds I've done I've never seen the one where the outer perimeter of part of the fitting was cut this way. Maybe some looked like this though?


I don't know when the unit was rebuilt, but it doesn't look like a diaphragm from Tangerine Racing was used or an OEM one. Wonder if the diaphragm came from another make of car?


If it were mine and I needed an MPS or wanted to have a spare on hand, I'd probably get Tangerine's rebuild kit and give it a go. If it still ended up being flakey after a fresh rebuild, I'd try and find a cheap failed MPS and swap just the diaphragm I just bought over to it.

[JeffBowlsby]

I have seen that early round pleat style diaphragm on early MPS's, usually the 1.7L (049s). I also have one of the outer serrated collar retention collar diaphragms in my collection of old diaphragms. Cannot be certain of who made it.

[FlacaProductions]

VERY interesting. thanks for doing this!
Not sure what to make of it!
I'm glad there is some "funkiness" though because it clearly didn't work in conjunction with the 123 - just curious how it still worked with the stock distributor!!

[Superhawk996]

So are you going to measure and plot the curve of this ?

[JeffBowlsby]

Speaking of funky...here is my current collection of MPS diaphragms.

Tangerine Racing's diaphragm is identical to the late style in the center as far as I can tell, all others are variations from who knows where. Each one depicted is unique from the others in some way.

[rjames]

So are you going to measure and plot the curve of this ?

Already did. See earlier post.

[rjames]

Wow, Jeff. That's a lot of variation. Safe to assume that some of these are not from 914s?

The one circled in red from your collection looks exactly like the one on my bench.

[JeffBowlsby]

Possibly, but not a 100% certainty. I don't see many non-914 MPSs.

[emerygt350]

What was the number on the housing? The spacer is also interesting. This was on a 1.7?

[rjames]

What was the number on the housing? The spacer is also interesting. This was on a 1.7?

Bosch 0 280 100 041
VW 022 906 051 E

Anders' web site doesn't show an entry for x041, but does show 022 906 051 E, which on Anders' site is associated with Bosch 0 280 100 049 (designed for a '70-'73 1.7 liter).

Spacer was likely added to accommodate a 2 liter, which is what it was installed on.

[FlacaProductions]

What was the number on the housing? The spacer is also interesting. This was on a 1.7?

it's my 041 - was on a 74 2.0 and "failed" when i moved from stock distributor to a 123.

but now that i think of it, i have not confirmed that it's a actually a 74.
I'll do that asap.

[Superhawk996]

What was the number on the housing? The spacer is also interesting. This was on a 1.7?

Bosch 0 280 100 041
VW 022 906 051 E

Anders' web site doesn't show an entry for x041, but does show 022 906 051 E, which on Anders' site is associated with Bosch 0 280 100 049 (designed for a '70-'73 1.7 liter).

Spacer was likely added to accommodate a 2 liter, which is what it was installed on.

For what it’s worth I also have an 041 that had a more typical copper beryllium pleated diaphragm. It too had a 2.0L spacer.

I don’t have history on the part. It came to me with a cracked diaphragm. I assumed it had been “adapted” previously since body is the early screw type and it’s easy to open without showing signs like those that have rivets. Now I’m really wondering (IMG:style_emoticons/default/confused24.gif)

Sorry I missed earlier post with curve (IMG:style_emoticons/default/headbang.gif)

[JamesM]

Just posting here for those that dont know about this reference. Lots of d-jet information as well as the most complete list/cross reference of MPS part numbers I know of


https://jetronic.org/de/d-jetronic/druckfuehler

[FlacaProductions]

@Superhawk996 - now THAT is curious...think someone was "rebuilding" these back in the day?

I don't think Brad Mayeur visits here much but I do know this motor was built by Brad before my ownership. Let me reach out to him to see if he recognizes anything.

I think there was at least one owner in the chain that I'm missing so it's entirely possible it was one of them...

[Superhawk996]

@Superhawk996 - now THAT is curious...think someone was "rebuilding" these back in the day?

@FlacaProductions

I honestly don’t know what to think. I suspect that all the cross references and websites may not be completely correct.

It very well could be that when they 1st started building 2.0L that initially intended 041’s to work for both 1.7 & 2.0l. Sort of like they did with the 73’ CHT? Switched plans at the last moment due to changing emissions regulations? Seems like a bit of a stretch.

It also could be that maybe 041’s intended for 1.7’s were trying to be commonized to use the same spacer as the new 2.0L to keep MPS builds easier? (IMG:style_emoticons/default/confused24.gif)

Or as you theorize - just someone tearing down 2.0L’s and then using in old 1.7L parts to jury rig them for 2.0L use.

Probably one of the unsolvable mysteries of 50 year old parts. I’ll end up trying to bench calibrate and then maybe someday tune via wide band on 2.0L and see how it all works out.

All I know is back in the day (late 80s) FI got torn of my car and my buddies cars at the first sign of trouble and all these MPS’s were either trashed ASAP and/or sometimes bartered for other parts when there was minimal information and minimal local parts support for these weird little cars. No telling what happened after that. Especially with these early MPS units held together by screws. It was a different world back then.

[rjames]

I’m confident that whomever “rebuilt” this MPS added the spacer along with the 1974 2.0 they wrote on the outside of it with a sharpie. I also suspect the diaphragm was from a non-914 MPS and used before there were reproductions available.