I'm programming a chip for a 1226870 running $1F and in the '%Change To AFR At WOT Vs. RPM' table the original values were mostly in the negatives, which obviously didn't look right. I thought it might be the wrong conversion math so I changed the equation to (0.390625 * X) + 0.000000 and here's the values I got:

% change
48.44
48.44
48.83
48.44
49.22
48.05
48.44
48.83
49.61
49.61
48.83
48.44
46.48
47.27
47.27
47.27
47.27

This can't be right so what's the correct equation? And I can't find the fan's on/off points. There's a fan enable temp and fan hysteresis, but that's it. Thanks.

 

The value may correctly be negative. If going from stoich to richer, need to reduce the AFR.

Not many folks around with that ECM. And not much is known about it.

RBob.

 

All the other wot AFR change tables are positive, which makes me think it's wrong. Is it possible that the fan enable temp is also the target temp?

 

The enrichment values are positive in other bins I've looked at too. I did a serch on the '870 and couldn't find much. Any help's appreciated.

 

FWIW, I believe that ECM is like a 7749 it has the better injector driver...
So why don't you consider going with code59.org
JUST FOOD FOR THOUGHT!
Ed


EDIT: are you running a 2.8 still ? if so ignore my last brain spaz!

 

Mine's a 2.8, but I've converted to a '165.

I'm doing this tune for someone else with an '86 2.8. He wants to keep the factory ecm for whatever reason, couldn't convince him to switch. So I'm stuck with this thing. But I'm willing to put up with it for a six pack. The 59 code is SD so doesn't help, but I was wondering would it be possible to use $32B with this ecm?

 

Bump.

 

The original equation in tunerpro for the '%Change To AFR At WOT Vs. RPM' table is (0.390625 * X) + -50.000000 but all the other enrichment related tables use (0.390625 * X) + 0.000000 so is this correct or is it a typo?

 

I'll try and help since there is so little info about the $1F bin and I can understand your frustration. First of all lets look at your question about the Fan. You have actually found the on/off points, you just don't know it.

The Fan ON point is determined by the "Fan Minimum to enable" value. This is the minimum coolant temperature at which the fan will turn on.

The Fan OFF point is defined by the "Fan Hysteresis" value.

Lets assume that "Fan Minimum to enable" equals 100, and "Fan Hysteresis" equals 5. That means that the fan will go on when the temp hits 100, and the Fan will then stay on until the temp drops to 95. Once the temp has dropped to 95, the fan will go off.

As far as the values in the %Change to AFR vs RPM at WOT goes, these values may well need to be negative. There is another table called %Change to AFR vs Coolant Temp at WOT, and you should find that table to have positive values.

So based on the temp, the amount of fuel added at WOT changes (This is correct), these values can then be further refined in the table that you are concerned with on an RPM basis. And based on RPM, it may make sense to refine the AFR. In my car (a V8), the values are all 0 in the table in question.

I hope this helps.

 

I actually managed to get a decent tune out of it, thanks for reconfirming my findings, though. If you happen to know the addresses of the maf scalars in $1F that would help out with my current project.