Going back to FI

vdubyah73 · Post by **vdubyah73** » Wed Jan 16, 2008 9:23 pm

Here we go, I have new, this summer dual 34 ICT's. I just got a complete FI system out of a '76. In my studying I read about a fuel enrichment thingie for heavy throttle operation. The '76 info is confusing to me, it seems that there is, or should be, either a micro switch or another different device located on the throttle body, to make this happen. I don't have either of these. I also read the later systems handled this task in the brain. My question is, how do I identify whether or not the brain is the right one for this enrichment. Or will the correct brain plug in and operate with a '76 harness.

Bill

tristessa · Post by **tristessa** » Wed Jan 16, 2008 10:51 pm

IIRC, there are two different systems in '76. The early one is the same as '75, the later one is the same as '77. I *think* the early system has one less (or one more?) connection to the AFM than the later one does. Not sure.

I finally got rid of the ICT's on my '75 about a week ago, installed a CIS system from an early-ish (1980) Rabbit. Those fscking carbs were so worn out they wouldn't hold an adjustment for more than a week, along with massive play in the throttle shafts. The linkage I had was crap too.

Pix in my gallery..

vdubyah73 · Post by **vdubyah73** » Thu Jan 17, 2008 7:24 am

My Weber's are new this summer and the rebuilt engine runs great. There is a very small bog on occasion with slight gas pedal movment, barely noticeable, but I feel it. That is not the reason I want to convert though, I only get 15 to 17 MPG consistently. With Gas prices seeming to be permanently hovering at the $3.00 a gallon mark I want some improvement. Plus the whole FI system was free.

It came off a '76 that ran well until the engine dropped a seat or stretched a valve. Don't know which, you can turn the engine by hand till it won't turn, and turn it the other way back till it stops again.
The throttle body doesn't have the micro switch, or the throttle valve switch. With some more studying, I see that I'm supposed to have the throttle valve switch. I'm guessing that it was removed when the EGR was disabled. I wonder if the lack of full load enrichment smoked the head?

So my question to the FI guru's is, can a later brain that controls full load enrichment be plugged in and expected to operate? If not, are throttle valve switches available? will they perform enrichment without a functioning EGR?

Bill

vwlover77 · Post by **vwlover77** » Thu Jan 17, 2008 8:31 am

How many pins are on the AFM plug on your harness, and what are the part numbers listed on the ECU that you have? That may help us sort this out.

vdubyah73 · Post by **vdubyah73** » Thu Jan 17, 2008 9:18 am

More info. My ECU is # 022 906 021 N, which is a '75-'76 Canada and USA application. My throttle body has no drillings for a throttle valve switch on the wings on the bottom. It also has no drillings on the top pad for the micro switch. Throttle body part # 022 133 067, I'm gonna assume it is a '77 or later. My air intake sensor or AFM has no plastic cover over the potentiometer. I can not find a part #. Is that where the part # is located? Again, can I upgrade to a '77 or later ECU and AFM or do I have to find a '77 or later FI harness as well. I'm concerned that I will smoke my Headflowmaster heads If I have a mish mash of different year components with a nonfunctioning full throttle enrichment circuit. I would rather stay with my trusty Weber's, that I am so familiar with, than venture into the world of FI. I can learn FI quickly. I'm a quick study with this kind of stuff. I just don't want an expensive learning experience.

Bill

vdubyah73 · Post by **vdubyah73** » Thu Jan 17, 2008 9:28 am

vwlover77 wrote:How many pins are on the AFM plug on your harness, and what are the part numbers listed on the ECU that you have? That may help us sort this out.

7 pins on the AFM and 7 in the harness plug.

18 pins on the passenger side as mounted on the ECU and 8 on the drivers side as mounted.
The ECU harness plug does not match the ECU.passenger side has 14 pins drivers side has 5.

Bill

Post by **Amskeptic** » Thu Jan 17, 2008 11:51 am

You are going to have to conduct a little research to at least match the AFM to the ECU. The 7 pins are the later AFMs as you now know, with the internal temp sensor circuit. The full throttle enrichment was incorporated into the ECU circuitry on the 7 pin AFM systems. Your supposition that the original engine may have melted due to lack of full throttle enrichment is extremely unlikely when you consider that people are brilliant at blowing up these engines for far more basic and obvious reasons.

Colin

vwlover77 · Post by **vwlover77** » Thu Jan 17, 2008 12:14 pm

Headflow Masters heads? How far do these deviate from a stock FI head design? What size valves do they have? What cam are you running?

Depending on the answers to these questions, you may want to stick with carbs.

Don't forget you'll need an FI fuel tank with an outlet pipe and a return pipe if you want to go to FI.

If you have a 7-pin AFM, that's the later setup, and I'd look for a '77 or later ECU to go with it, if you decide to go that route.

Post by **Amskeptic** » Thu Jan 17, 2008 12:47 pm

vwlover77 wrote:Headflow Masters heads? What size valves do they have? What cam are you running?

Don can tell you all about valve/cam compatability. . . .

You do not want anything bigger than 39mm on the intakes with stop FI.
I tink oem was 37.5?

vdubyah73 · Post by **vdubyah73** » Thu Jan 17, 2008 2:14 pm

vwlover77 wrote:Headflow Masters heads? How far do these deviate from a stock FI head design? What size valves do they have? What cam are you running?

Depending on the answers to these questions, you may want to stick with carbs.

Don't forget you'll need an FI fuel tank with an outlet pipe and a return pipe if you want to go to FI.

If you have a 7-pin AFM, that's the later setup, and I'd look for a '77 or later ECU to go with it, if you decide to go that route.

Stock internals in the long block

Stock, new, AMC heads, with a valve job to replace the so so quality hardware. $1150 a pair last winter.

The part # for my ECU is 022 906 021 N. 1975-"76 ECU for USA and Canada. I need a 1977 or newer?

I could not find a # on my AFM Do the seven pins identify both my harness and AFM as the later model with the ECU controlled enrichment?

I have the FI tank.

Do the early AFM and harness have more or less pins?

Do the earlier ones have the same amount of pin locations, just some are blank?

I'm gonna be bugging you FI guys, picking your brains. Not doing the reversion back to FI quite yet, have to pull Buggy engine to install cooling flaps and thermostat. Took a while to find flaps but I have them now. Could use a return spring. Think I can find something in the hardware store.

Thanks Bill

vwlover77 · Post by **vwlover77** » Thu Jan 17, 2008 5:20 pm

OK, I'm extrapolating a bit here from old information, BUT....

The Factory Repair manual in Supplement 6 dated September, 1976 says that '77 models have....

1) New ECU # 022 906 021 S
2) New AFM # 022 906 301 D (this would be on the lid you don't have)
3) Full throttle contact DISCONTINUED

And the AFC manual says the ECU and AFM part numbers are....

'75 - Jan '76: ECU - 022 906 021 H, AFM 022 906 301 A
Feb '76: 022 906 021 N, AFM 022 906 301 B
'77: 022 906 021 S, AFM 022 906 301 D

I'm thinking the D revision of the AFM is the one that changed to 7 pins, so if I'm right, your ECU is NOT correct for the AFM and harness that you have.....

Can anyone verify?

vdubyah73 · Post by **vdubyah73** » Thu Jan 17, 2008 7:42 pm

I get so confused

I think what I have here is a mish mash of parts. I removed them from the junk bus my self and I think that I may have a 76 harness and ECU with a later throttle body and probably AFM. There are a pair of white wires, sheathed, in the harness that have been cut. They come out of the harness within inches of the ECU plug and show continuity on 2 terminals. in the plug. On what would be the passenger side of the plug, when installed, and counting every hole, from the top, with or with out a terminal in it. I show continuity at 7 and 10. The terminal numbering system does not make sense to me as it appears there are two different systems of numbering. One in the electrical section and another in the FI section of the Bentley. When looking further into the FI chapter, on page 21 it shows an ohmmeter test for the throttle valve switch, which is what I should have according to the junk bus VIN #. There are no terminals at 48 or 3!
I was able to scrounge up an ECU for a 1978 USA/Canada bus
022 906 021 AG this afternoon. A throttle valve switch and AFM for '76 are available from the same source but I don't know how to figure if I have the harness or AFM from a '76 or a '77 and later bus. I have to figure out the year of the harness. The terminal configuration on the "N" and the "AG" ECU's are the same. There are terminals on the ECU that have no corresponding terminals in the plug. WTF, it does not make sense, am I thinking too much?

Bill

vwlover77 · Post by **vwlover77** » Fri Jan 18, 2008 5:57 am

Hoo, boy, now I'm confused too.....

For questions about your harness, you might want to contact Kyle through his web site. He's the guy that makes the replacement FI harnesses, and he might be able to help you identify what you have.

http://www.kyleautomotivespecialties.com/home

IIRC, the only wire that comes out of the sheath close to the ECU plug on later harnesses is the lead the runs over to connect to the negative terminal of the coil. I'm not sure why you have two wires at that point, unless the other is indeed for the full-throttle switch....

vdubyah73 · Post by **vdubyah73** » Fri Jan 18, 2008 7:00 am

The cut wires come out at the same location as the coil - wire. I'm thinking the same thing, except pg. 21 shows an ohmmeter test using terminals 48 and 3 on the ECU plug. The photo shows the location of the terminals to probe. The terminal locations in my ECU plug are both empty.

Bill

Post by **Amskeptic** » Fri Jan 18, 2008 10:14 am

vdubyah73 wrote:The cut wires come out at the same location as the coil - wire. I'm thinking the same thing, except pg. 21 shows an ohmmeter test using terminals 48 and 3 on the ECU plug. The photo shows the location of the terminals to probe. The terminal locations in my ECU plug are both empty.

Bill

Bill,
You are allowed to utilize your native intelligence and to hell with the dumb mysteries. Go to the Bentley manual with a piece of notebook paper and a pen. In the FI wiring diagrams, you will find answers to all of your terminal questions. There are dead terminals all over the place as they met differing market's requirements. I apologize for Bentley's lousy printing and shrinking of the diagrams over the years (I apologize?).
If you get stymied, I will bring in my earlier Bentley with the good diagrams and help you through it in the evenings over the weekend (01/19-01/20).
Colin

Itinerant Air-Cooled

Itinerant Air-Cooled

Going back to FI

Going back to FI