1976 280Z ECU and AFM question

[pamato]

I have a early 76 280Z (8/75) that I do not have a correct ECU for.

I could not find a compatibility chart for the the correct ECU for a early 76.

The AFM in the car is a A31-060-001.

I spoke to MSA but they could not tell me what the correct ECU was for my car.

Additionally the car has California emissions.

 

Thanks in advance

[Zed Head]

What's the number on yours?  Share.

 

Here's a Nissan Service Bulletin that I found on the internet a while ago.  Looks like they all used the same, except for 1975, and 77 and 78 AT models.

NTB94-097 (Nissan ECU Guide).pdf

[pamato]

The number on the ECU that I have is A11-600-000 but the car does not run right with this ECU.

 

Additionally, it has a Automatic Transmission as well as being a CA car.

 

[wheee!]

I have a couple extra units, unknown condition...

 

http://www.classiczcars.com/topic/51048-fi-ecu-mods-and-differences/page-1

 

but they are the same as the one you have. I don't know what you mean by doesn't run right tho....

Edited September 17, 2015 by wheee!

[Zed Head]

The number on the ECU that I have is A11-600-000 but the car does not run right with this ECU.

 

Additionally, it has a Automatic Transmission as well as being a CA car.

That's the right ECU.  The problem might be from something else.  We could probably offer some advice if you added some details to the "does not run right".

[pamato]

Typical 280z issue with it running lean, popping back through the intake.

replace the temperature sensor, tweaked the AFM, verified all vacuum lines, verified aux air functioning, checked all electical connections at the ECU connector (all within FSM spec).

If I unplug the temperature sensor wires engine goes full rich.

Have verified that @ 68 degrees F, the ohms at the temperature sensor, at the harness and at the ecu are within spec (2580 ohms)

[Zed Head]

Typical 280z issue with it running lean, popping back through the intake.

 

Fascinating that so many of us adjust the AFM to try to fix this problem.  I did the same when I first got my car and ended up buying a new one from MSA.  But my test numbers were way off.  Still I might have been able to make it work using the other atlanticz Z "tweak".  I have two, maybe three, AFM's that needs this tweak to work.  It's the most direct way to get it done.

 

http://atlanticz.ca/zclub/techtips/tempsensorpot/index.html

 

 

Forgot to say - put your AFM back where it was.  Blue's technique is for recalibrating to factory specs., not tuning.  Many people just read the theory of what happens and use it for tuning.  But it doesn't seem to a linear full spectrum fuel enrichment, like the potentiometer is.

Edited September 17, 2015 by Zed Head

[pamato]

Yes, had to reset my AFM spring and wheel thingy back to the factory marks with.

What's the correct number of turns from closed on the idle air screw on the AFM?

 

Borrowed a couple of other ECUs from a friend and tested them. One would idle great but would bog down upon acceleration, the other wouldn't idle well and popped just like mine does.

 

I guess it's time to shop for a ECU.

[Zed Head]

Your time, and your money.  Might as well send the money to a member though.  wheee! seems like a good guy and could probably use it for his project.  Post #4.

[Zed Head]

A maybe helpful comment - the ECU's usually go completely bad, either running super rich or not running at all.  Your lean popping symptoms indicate the need for more fuel, which is not a common bad ECU symptom.

 

Also, I notice that you mentioned electrical testing but nothing about fuel pressure.  Another potential cause.

 

Anyway, good luck.

[EuroDat]

Running lean. What is your fuel presure doing?

There are various problems in the fuel system that can cause low pressure and create a lean condition.

You might want to do some more testing before throwing money at it. Have you downloaded the EFI Bible?

Even simple penny and dime stuff can add up quick. Just saying...

[siteunseen]

Mine would buck and stumble until it got over 2,500 rpms, then pull hard.  I couldn't figure it out and carried it to a mechanic that worked on these cars back in the 80s.  He adjusted everything back to spec and the problem was still there.  He clamped the return line to raise the fuel pressure and it ran better.  I almost bought an adjustable fuel pressure regulator, the high dollar one that works on these cars, Airtex maybe?  Anyway, after reading some post from Fastwoman about the ECUs drifting out of specs from heat and old age I put a potentiometer in the cabin from Radio Shack.  Ran some speaker wire from the bullet connectors through the firewall, it is still laying in the passenger's floorboard.  It's a volume knob type that cost $5.  After playing around with it my car runs great now.  I can turn it and get better gas milage on the highway, I can turn it and watch the temp gauge get cooler or hotter, it has been fun to play with.  Now I want to permanetly install one under the dash, right before the ECU, with a finer adjustment using a small screwdriver.  Like this, http://www.classiczcars.com/topic/37549-purs-like-a-kitten/page-4

Post #66