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[T3] DYI EFI Replacement (long)


List & Jim

I printed out most of the info on this and read it last night. The MAP sensor is U3 in
the lower right hand corner by the big plugin in the PC Board layout. It is between c4
and c2 (caps) .  My 97 Passat TDI had a vacuum hose(?) going to the ECU from the
engine, so I would think the Idea is sound. (at least to vw) The ECU (computer) in all
of the w/c vw's are in the rain gutter under the window wipers so I think the
connections and case must be water tight. I did not see a place for the vacuum hose to
go into the case but their was not a shot of the ECU cover.
They say the MAP sensor is a must. 6 input signals (sensors)

MAP = Manifold Absolute Pressure
MAT = Manifold Air Temp
CT    =  Coolant Temp
TPS  = Throttle Position
Ignition Sensor (coil input)
O2 Sensor

Most all modern EFI's, OEM and after market use these inputs, some use MAF (Mass Air
Flow) instead of MAP, or Crank Trigger for ignition input. (our FI trigger points)

I have been watching (lurking) around the diy-efi group for some time. I have been
interested in find a reasonable replacement or conversion to the Type 3 unit (which I
like). But it is a real PITA to redo what someone else (not me - right!) has butchered,
or removed. I have looked at most after market EFI units, Haltech, TecII
(electromotive), Wolf, SDS and more. I have thought the SDS was the most likely
replacement but it would still cost over $1000.00 to do one.   (NO Flames Please, from
the Haltech or TecII lovers ; >)
On our OEM units, is the CHT used just at startup or is it user at other times? i.e.
warm-up mode fuel enrichment. I think that is all it is used in the SDS unit. After it
reaches a certain temperature (170f + ) it is no longer used.

If no one can tell I am pumped up, hyped up about this. For other uses too, not just
Type 3.
For Type 4, My Rabbit and others ...I have learned a lot about EFI from my first
Squareback. FI from my Rabbit. Though I am far from being a expert, I think I have a
good handle on what makes them tick.
More to come......
Richard

PS: We don't need to go out and change our working EFI systems, they work just fine.
My propose is for conversion or massive failure.


>
> Jim Adney wrote:
>
> > Now THIS looks really cute, and I'm impressed that someone has actually
> > done the work for all of it. I am also just starting to read their stuff, but I
> > notice one problem: There is an absolute pressure gauge mentioned
> > somewhere on the schematics, but it's not there on the wiring diagram. In
> > fact that's a big problem because as shown there's nothing that tells us how
> > much air is going into the engine. (Throttle position itself is not enough.)
> >
> > Oops, I see it mentioned now. It's a Motorola chip mounted right on the PC
> > board, but I don't see it (means little) nor can I see where the vacuum line
> > comes into the box. I wonder if that chip is okay with gas and oil fumes, etc.
> >
> > -
> > Jim Adney
> > jadney@vwtype3.org
> > Madison, WI 53711-3054
> > USA
> >
> > -------------------------------------------------------------------
> > Too much? Digest! mailto:type3-d-request@vwtype3.org Subj=subscribe


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