ECU part numbers for 1975 L-Jet, looking for info Options

[rick_cv]

Trying to piece together an L-Jet fuel injection system with the parts I currently have. Missing the ECU and have a 6 pin AFM. Does anybody know what the correct ECU part number is for a 6 pin AFM? The early 1974 411 has part number 022906021F and the going rate is 1/3 the price of a 1975 914 unit, part number 022906021G. A 1975 bus ECU typical part number is 022906021H. These are all indicated for manual trans but not sure which AFM they work with. Thanks

[wonkipop]

6 pin connector is 74 1.8 l jet.
some of the info you are looking for is on page 1 of thread linked.
(originality forum of this website).
scroll down half way. ECU part #s is listed for 74 and 75.

http://www.914world.com/bbs2/index.php?sho...357407&st=0


further down the page is a CARB emission document for 74 MY vws.
CARB document implies 74 412 shared the ECU and AFM with the 914.
part # 022 906 021F is the AFM on the CARB doc.
part # 022 906 031 is the ECU
except if you look close it appears as if the CARB document has the part #s between the AFM and the ECU the other way around compared to 914 factory manual.

i'll have a look back through the parts catalogue and see what i can find.
just to verify this.

[jim_hoyland]

I may have some ‘75 parts for; not home at present. But will post later

[wonkipop]

ok - i took a look at 914 parts catalogue.

so its the CARB document has the parts #s scrambled on AFM and ECU.

the 914 factory manual agrees with the parts catalogue.

the ECU is 022 906 021 G.
the AFM is 022 906 301

so what you say is correct if we reference the CARB document and make the correction that the AFM is 022 906 301 and the ECU is 022 906 021F for a 412 with L jet.

i can only take a guess at this but the F version is the early version superseded by the G?
(maybe?).
the 412 1.8 L jet went into production 3 months before the 914 with the 1.8 L jet.
so likely had first versions of everything. by the time they got to the 914 they had already got to the G version of the ECU?

but the only way to verify this would be to have a 412 parts catalogue USA version.
if it is anything like the 914 parts catalogue it will list superseding variations.
unfortunately the only catalogue i can find is on the VW classic germany website.
this is the european parts catalogue and does not cover 1.8 L jet for 412s.

but if you asked me to take an educated guess its possible that the F unit works.
CARB are listing the 914 as running that F unit in the emissions approval docs for california. so its possible i guess that very early 914 L jets did have it?

the differences between the two engines looked to me to be mostly in the way they set them up for emissions. the 412 ran EGR in 74 and i think it did not have the same distributor. but i'm guessing the rest of it is pretty much the same.

[wonkipop]

Trying to piece together an L-Jet fuel injection system with the parts I currently have. Missing the ECU and have a 6 pin AFM. Does anybody know what the correct ECU part number is for a 6 pin AFM? The early 1974 411 has part number 022906021F and the going rate is 1/3 the price of a 1975 914 unit, part number 022906021G. A 1975 bus ECU typical part number is 022906021H. These are all indicated for manual trans but not sure which AFM they work with. Thanks

the F G H sequence makes sense with the phased intro of L jet.

the 412 is first. 3 months later then 914 and the bus comes 3 months after the 914.

the 412 was fully automatic gearbox only.
(manual 74 412s had 1,7 d jet engine retained and were only 49 states and only fastbacks).
914 was manual.
the bus according to the CARB doc is a manual.

so its hard to know if that is a superseding sequence or it does point to the ECUs being different in some way. tricky. but it is interesting that the CARB doc does not list those sequence of ECUs when it was issued. just lists approval for the F version on all three.

EDIT
the part # you are listing for a 75 914 ECU is the part# the 74 ECU.
the # for 75 is 473 906 021 and the 75 is the 7 pin connector from AFM to ECU.

different AFM, connector and ECU on 74 to 75.

clay perrine might have a better idea of whether you can mix and match the 914 ECUs and AFMs and how that might be done.
(IMG:style_emoticons/default/beerchug.gif)

it would be interesting to be able to get to the bottom of the F G H business on the 74 ECUs for l jet. pure production numbers alone would say there is 3 times as many 412 L jet ECUs lying around somewhere presuming they did not all end up rusting in junkyards.
could even be stashes of NLA 412 ECUs still around.
with spare parts getting harder to find it would be nice to know if its a viable alternative.
as you discovered its cheaper, but it might also get to the point where we are scraping the barrel for spare parts if we want to keep original L jets going.

[rick_cv]

Thanks for the info. I will take a look and see what part number my AFM is and try to cross reference it on these charts. It is confusing with 6 pin/7 pin difference and what ECU works. I believe the wiring harness (which I also have) varies too.

[JeffBowlsby]

The 914 Ljet harnesses are easy enough. There are basically only two. 74 has the 6-pole AFM, 75 has the 7-pole AFM.

[wonkipop]

Thanks for the info. I will take a look and see what part number my AFM is and try to cross reference it on these charts. It is confusing with 6 pin/7 pin difference and what ECU works. I believe the wiring harness (which I also have) varies too.

the 914 stuff is easy.
its listed in the parts catalogue for the 914s.
for 74 and 75. the way they do it is note it as after a certain EC engine number.

its been extracted out in that thread i linked to to make it a little easier.


-----

the interesting question you ask is would the 74 412 ECU be compatible.
i don't know to be 100%.
its a worthwhile question but hard to get to the bottom of.
there were only 412s with L jet for 1974 MY so that would be the only one to look into.
74 ECU compatibility. it would be a six pin like the 914s.

in 75 the 1.8 engine is only going in the 914s, the 412 is over at that point.
and as mr. b notes - different AFM, different ECU and has 7 pin connector harness.
that might be the only real difference, the 7 pin harness.
the way the engine runs as mapped by the ECU is probably the same.
49 states 75 1.8s were basically californian 74s.
they did change the decel valve. that was different from 74 to 75.
but i do not believe they "essentially" changed anything else.

[wonkipop]

clay perrine knows a huge amount of detail when it comes to these components.
he will occasionally go into it. (IMG:style_emoticons/default/biggrin.gif)

what we have been able to find out is that even though they list the AFM for 74s as the one part #, when you rip them apart inside they were even modifying that on the run from early ones to later ones. particularly how they were building in the temp sensor.
its the first year of L jets on anything and the VW version is basically the prototype.
its not on anything else anywhere else in the world except the USA.

the ECU on the 412 L jet could have been mapped differently.
its an automatic exclusively. no manual gearbox.
so thats my hesitation in saying its exactly the same - despite the CARB documents.

[wonkipop]

@rick_cv

this probably answers the question on ECU compatibility with other VW L jets.
from ratwell's bus website.



there is a bit of a mystery as to whether there ever was a 74 bus for california with L jet, despite CARB documents with approval for one.
but the california air resources board approval was granted for one.
manual only with the 022 906 021F ECU.
so who knows.

but ratwell says for 75
there are two different bus ECUs.
022 906 021H is for the federal bus with a manual gearbox.
022-906-021J is for the federal bus with an auto box.
i'm guessing the ECU must be different for manual v auto and is not interchangeable.
if they were they would just list the same ECU? (IMG:style_emoticons/default/confused24.gif) so must be something different in the mix.

i can tell you that the 412 one listed as 022-906-021F was only ever in automatic gearbox equiped 412s. the L jet was only installed in auto gearbox 412s.

using bus logic of ratwell that F ECU isn't going to be good for a 74 1.8 (or in your case a 75 using 74 parts).

i do know my aussie colleague @nihil44 up in brisbane has been having a go at assembly of an L jet system on a 76 model he has using various bus parts, ECU ?, AFM? etc but i don't know if he has achieved success yet. he was having some trouble making it run properly.
if he reads this he might give you his thoughts.

[rick_cv]

Thanks for the info. I know 022-906-021G is the proper ECU for a 75 l-jet that I should use but still not clear if that works with the early 6-pin AFM. Maybe I will stumble across a complete system eventually and won't have to worry about this.

[wonkipop]

Thanks for the info. I know 022-906-021G is the proper ECU for a 75 l-jet that I should use but still not clear if that works with the early 6-pin AFM. Maybe I will stumble across a complete system eventually and won't have to worry about this.

no mate.
that is a 74 Model Year ECU part # you are quoting. the 6 pin plug goes with that ECU. the 6 pin also goes into a 74 specific AFM.

the 75 model year ECU is part # 473 906 021. that goes with the 7 pin plug. the 75 AFM is also different and goes with the 7 pin.

but it will work on either a 74 or a 75 1.8 so long as you have the three things lined up.
the ECU, the harness connector and the AFM.

[theer]

Thanks for the info. I know 022-906-021G is the proper ECU for a 75 l-jet that I should use but still not clear if that works with the early 6-pin AFM. Maybe I will stumble across a complete system eventually and won't have to worry about this.

no mate.
that is a 74 Model Year ECU part # you are quoting. the 6 pin plug goes with that ECU. the 6 pin also goes into a 74 specific AFM.

the 75 model year ECU is part # 473 906 021. that goes with the 7 pin plug. the 75 AFM is also different and goes with the 7 pin.

but it will work on either a 74 or a 75 1.8 so long as you have the three things lined up.
the ECU, the harness connector and the AFM.

@rick_cv

Turns out I have the “G” ECU. No idea where it came from, since I had a 1970 which I converted to carbs many years ago. Anyway, it’s yours if you want it. Just let me know.



Tom

[rick_cv]

Thanks for the info. I know 022-906-021G is the proper ECU for a 75 l-jet that I should use but still not clear if that works with the early 6-pin AFM. Maybe I will stumble across a complete system eventually and won't have to worry about this.

no mate.
that is a 74 Model Year ECU part # you are quoting. the 6 pin plug goes with that ECU. the 6 pin also goes into a 74 specific AFM.

the 75 model year ECU is part # 473 906 021. that goes with the 7 pin plug. the 75 AFM is also different and goes with the 7 pin.

but it will work on either a 74 or a 75 1.8 so long as you have the three things lined up.
the ECU, the harness connector and the AFM.

@rick_cv

Turns out I have the “G” ECU. No idea where it came from, since I had a 1970 which I converted to carbs many years ago. Anyway, it’s yours if you want it. Just let me know.



Tom

That would be great! I will pm you.