mjr

Also I saw your note on the AAR above. The HellFire alone won't magically fix your AAR issues. I have an idle air valve control output on the HellFire Hybrid, but it's not plug and play by any means. We will have to find an aftermarket Idle Air valve that will have to be retro-fitted in place of the AAR with the associated wiring & air line plumbing. I do have some nifty ideas about this, but it won't be ready for the initial release.

BTW, my plan is just to use my foot for the extra air needed to warm up the engine.

Len

Len, there are 2 white wires that are just hanging by the ECU. I was under the impression that there was an altitude switch in the AFM. Thanks.

Mike

Mike,

That's the wires that would go to your Altitude switch under the dash if you had one. I'll be out in the shop fouling plugs with HellFire today, so I'll try and play with that circuit on the stock ecu and look at the outputs on the scope.

Lenny

Thanks Len, this whole rich running thing has me totally baffled!

regarding post #60.....did you find it?

rcb, can't find anything up there except my old e flasher unit that I haven't been able to figure how to remove.

So I guess the next thing would be to find out if you are supposed to have one. I also wonder if there is a difference in the ECU's. In other words, are there ECU's with and without the pins for the altitude switch? Mine is on page EF-15.

The two white wires have been discussed before. They're "Control Unit Checking Terminals". Can't remember where the altitude wires come out of the harness. You could probably use them to do the same as lowering fuel pressure though. Quick fix. I think that they just need to be shorted, the altitude "sensor" is really just a normally open switch if I recall right.

Edit - Actually, superlen and I had an exchange about the wires in a past thread. Apparently there are extra black wires and extra white wires depending on the harness. Probably best to trace the wires to the pins to know exactly what's what. The FSM describes the altitude switch and probably has the diagram back to the pins. You could probably wire in your own switch if you wanted to try it or jump it with some test leads to check it out.

Edited March 1, 201411 yr by Zed Head

Zed, the 2 white wires appear to be coming out of the wiring harness well above the plug for the ECU, so I'm kind of a little lost as to what they are and what they do. In some other previous thread, I'd read they were "possibly" used to connect an altitude switch, but I'll at least do some electrical checks (I'm just starting to be able to use my digital meter, I'm an electrical novice and get lost easily) on those wires and the #11 and 26 terminals.

Mike

Mike, I went out to look at mine. I looked for the shape like the diagram in EF-15 shows. It is hard to find. Look for a brass colored device with wires coming directly from one end. There are 2 wires(one blue and one blk) coming from it (altitude switch) to a connector and from that there are 2 wires which are now both blk that follow the ECU harness towards the firewall, not to the ECU. I will have to investigate this some more now. I thought they went directly to the ecu. Have to look at my over sized wiring diagram.

Took a look through the FSM's and see that the "atmospheric pressure signal" didn't show up until 1977. California models only. Page EF-7 in the 76-78 FSM's (not shown in 76, shown in 77). Pins 12 and 9 on EF-25 in the 77 book (now called an altitude switch, shown right next to the ECU). EF-23 confirms it's just a switch.

Weird stuff.

What's really interesting is that to "go lean" the ECU looks like it changes the resistance on the pin 9 circuit. Might give a clue on another way to tweak the mixture. Maybe the thing shown in the AFM is the reference resistance for the circuit and decreasing its resistance leans the mixture. I'm guessing that Pin 12 is another resistance, added in parallel to pin 9. Someone else with more electrical would know better.

Edited March 1, 201411 yr by Zed Head

rcb, nope don't have it in there and in my FSM diagram EF 15 shows the thermotine switch location, go figure. I've come to the conclusion that not all FSM's are created equal.

Edited March 1, 201411 yr by mjr45