TeufelHei

I finally figured out which wires were which on the O2 sensor and AFRM. Silly me, I had them mixed up.

O2 sensor is brand new three wire unit from the biggest of the three. ARM-1 from the second biggest.

Here's the trouble:

On start the AFR is near/at lambda. Reads .53 volts on the multi-meter which corresponds to the lambda reading.

After about ten seconds, the ARM-1 shows a drop in fuel concentration. It is a steady drop from center yellow (14:1) to bottom red (17:1) over a period of about thirty seconds. The multi-meter is reading the same thing. Here's the trick, it drops so low in voltage that it starts reading a current draw of about -.3V while running warm.

It seems as if the car runs fairly well, power is smooth (thanks to newly balanced injectors and motor mounts), and fuel pressure is steady at 38 PSI.

Two suspects: MAF and the weird little computer that is spliced in for federalization purposes (presumably).

Any help?

TeufelHei

it should be noted that this is not a new development (lean condition). I have been working to TS it for a while.

AO

When you first start it runs closed loop for about a mintue thus the ARM1 will not hunt. THen after it warms up a bit, you will see it hunt. At idle it should read down in the red area (rich), then when you punch it, you should see it shoot to the right as RPMs increase. On my '82 it would get to the first blue light.

AO

I guess what I'm saying is that this sounds pretty normal.

TeufelHei

Could be wrong, but I thought rich was blue and lean was red...

It doesn't hunt. It sits at the last red and goes nowhere unless I goose it a bit. Then it goes to blue for about half a second, then back down to red.

Louie928

Doesn't sound right. It should be rich for a short time after startup from cold, then go to closed loop with the mixture hunting around near the center until you go to moderately high power. Then more steady, but on the rich side of center. What's this "weird little computer" thing spliced in? Where exactly is it? I'm not aware of anything extra that should be there. On an '85, the fuel pressure shouldn't be steady. It will change with throttle opening (manifold pressure).

FlyingDog

If it was my car, I'd rip out the federalization crap and go back to standard 100% open loop. Your car was not meant to run closed loop or have an O2 sensor. Just run the ARM-1 with the O2 sensor.

AO

Yeah... you might be right on that. I have one ready to install on the GT, but I bought it before I ordered the SC kit from DR. So I haven't seen one since I sold my 82 with the NOS kit. I do know that as I'd accelerate, the lights went toward bluw, then as soon as I lifted off the gas it went straight to red in less than 1 second. I was told this was normal. Idle would usually be in the red area.