Fuel injection relief here!

[KTPhil]

You can use the electric AAR on a 4-speed. They came with the mechanical version, but still included the red wire to heat the electric AAR. The front end is clipped off but you can find it in a wire bundle under the dash. I use mine to work the tach now. The back end is also clipped but you can splice/extend it by peeling back the wire bundle sheath. I think it's with the oil light wire.

[desmato]

So, is that to say i need to have power connected the this AAR for it to work correctly ? It doesn't close otherwise. The oil sense wire is green (supposed to be Blue w/green according to the Bentley...) and there is an orange wire with it that is clipped. I'll check that for power and i assume ground the other pin ?

[desmato]

Ok, so with the exception of the electric AAR, I've chased everything down and measured what i could. Compared them to the values i found in the Bentley and...... all are within specs (didn't do the cold start valve or sensor) sadly, there is no voltage on the 'red' wire alongside the oil light wire. I either need power tocthat AAR switch or change it out to the correct one.

I found a 'B' ECU and wiring harness in a box that must have come with this engine (telltale ground lugs on both sides near the injectors and temp sensor in bottom of head). I also found the couple of 68-9 items that were swapped out like a 68-9 pressure valve.

That all said. Here are my values:
Temp sensor in head ~2280 Ohm @ ~65*F
Temp sensor in air plenum ~280 Ohm @ ~65* F
Pressure sensor, outer terminals 90 Ohm
Pressure sensor, inner termimals 330 Ohm
Which are all within what the good book shows.

I bumped the timing a little, replaced a leaky exhaust gasket and drove it a few miles. Seems to be better but without full realtime tuning, it's all by the butt.

At this point, I'm gunna disconnect the cold start setup just to make sure, go through the timing (with an actual light) check the points/dwell and go from there.

Any pointers ?

[KTPhil]

The electric AAR is powered when the ignition is on, from up front at the fusebox. The AAR has an electric heating element that closes off the airflow after a while. Similar to a carb choke that opens with heat; but this closes with heat.

It's a snake nest up front but if you look you can find the clipped end under there. I do not remember which fuse it connects to. Find one that does NOT have "always on" power, but rather find one that comes on with the ignition in the RUN position.

Most AARs flow a little air even when warmed up, that's normal (electric or mechanical, both leak). It's just another slight air leak (throttle bypass) that raises the idle a bit, but you can compensate with the "regular" idle speed adjustment stud and locknut on the IAD.

[desmato]

Makes sense. If it just needs switched ignition 12v can't i tap from the coil that's a few inches away ? Then i could use that red wire for a tach.

[KTPhil]

[KTPhil]

Clipped wire at rear:

[MARTYB]

Hi Members. Would anyone know of the link or page number to find the correct way to adjust a 5 pin throttle valve switch off a 1972 Fastback, Tried to do a search and havn't found it yet

Also i have been told to check that the TVS is showing the different resistance readings throughout the range as when operating the accelerator pedal to check its working correctly
Would anyone know how i can do this with my multimeter
Thanks for looking

[tmitoraj]

https://www.thesamba.com/vw/forum/viewtopic.php?t=683230
This is from Ray in the 411/412 forum on TVS adjusting

[MARTYB]

Thanks Tmitoraj for sending that link.

[desmato]

KT... funny as Mine looks exactly like yours. I do like the idea of that wire for the tach.

[MARTYB]

A big thanks to Ray for doing the excellent info on adjusting TVS and how to optimise their operation as it made a difference with my cars running.

I have another question if any members can help with.
This 1972 Fastback has always ran not ideal when cold. I checked the 2 x temp sensors and their ohms readings are in range when cold and hot.

A VW manual by John Muir explains checking components via the wiring loom with the ECU removed.
I found doing it that way the reading between wiring loom numbers 1 and 13 at the ECU plug for temp sensor 2 in the intake manifold was only 4.8 ohms cold compared to 326 ohms for the sensor itself with no wires plugged into it.

When checking the wiring harness that plugs into temp sensor 2 someone has cut into the harness and redirected one of the 2 wires that should go to the ECU plug and instead connected it to what i think is the thermo switch with the single male terminal under the air intake manifold !!!
Wiring diagram shows the thermo switch should connect directly to the cold start valve instead.

Would anyone know why this mod has been done as i'm thinking the ECU is getting a reading from one sensor that it needs to be running richer when cold and the other wrongly connected sensor is telling it to run lean as in a hot running mode ?
Thanks for reading this post

[tmitoraj]

How does the heating element in the auxiliary air valve turn off after it heats up enough to stop the flow of air through it?

[KTPhil]

[bploe]

Hello All, New here and new to Fuel injection air cooled VW. My first car was a 69' VW Beetle unfortunately it was stolen and then wrecked many years ago. I have recently inherited a 73' fuel injected fast back. Car is in great shape and was told all it needs a new battery and may have a fuel leak. I got a battery and wow it had a fuel leak. Every hose at the pump was blown out. I fixed/ replaced all hoses at the pump. Gassed her up and nothing. Turns out the fuel pump is shot. After many exhausting months of hunting for the infamous Bosch 3-port pump i finally found one at a crazy expense. After installing it it didn't want to run. After flipping polarity and a gentle tap tap it worked. Started the car (she lives) ran for about 5 minutes and then stopped pumping. I have done everything I did on install to get her going to no avail. Are these pumps really that bad? Should I go to the Airtex E2000? or mess around with this one some more with the soak in diesel routine? If i convert to the Airtex what do you do with the return that currently hits a t and goes into the pump? Any advise would be greatly appreciated. I've had this thing for over a year and put some money into it and still feel like I'm at square 1. Very frustrating here.

[Tram]

[Bobnotch]

[MVB]

Would the simplest way to convert to fuel injection from carbies, to go for one of those slide throttle TBI setups from Rotec? They are very simple with just an idle setting that can be locked down & on the fly throttle & mixture by either Bowden cable or rods.

https://www.youtube.com/watch?v=c9PyeXttRQs

They do make a model for VWs

I have a Stan Pobjoy Racing 1916 with twin dyno jetted Solexes & I’m getting sick of the petrol bills

[Tram]

Problem on a Type 3 would be getting it to fit under the deck. Do they make a twin setup low enough for this?

Stock FI tops out at 1776. Even then you need the blue injectors from a Mercedes 4,5 rather than the stock yellow ones. But beyond that displacement the air intake system will choke it.

If you're sick of the petrol bills your best bet is a stock 1600 either carbed or injected. Sorry.
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[MVB]

Thanks for the reply Tram

At it guess, packaging wise, it seems one would have to use 2. I s’pose one just halves the mixture settings & double the thickness of the return cable springs on the throttle slide controls & do equivalent regards the on the fly mixture controls.

This is the one listed for VWs:-
https://www.rotecaerosport.com/tbi-34-2

I’ve been told that to dial the mixture settings well, a vacume gauge or manifold pressure gauge would help. Are they just 2 different names for the same gauge?
Rotec also market an “air fuel ratio kit with a wide band Oxygen sensor” for use with the TPI.

Obligatory linkage:-
https://store.rotecaerosport.com/air-fuel-ratio-kit