caledit / BE gurus.. odd situation

[nc89sho]

trying to dial in my mk viii maf, and no matter what i set at the idle voltage, i consitantly get lean conditions / Fuel trims in the positives. The car idles at somewhere around 3 volts. i have set the value there as high as the mid 12s and i get the same condition.. thought i might have a vacuum leak, but can't find one. any ideas???

 

[yamahaSHO]

Explain how you're setting the idle voltage?

 

[nc89sho]

not setting.. i was reporting to you guys what the idle voltage was. i was setting the number in the transfer for that voltage to as high as 12. not changing the voltage.

 

[Ishodu]

Post a screen shot of your MAF transfer

 

[nc89sho]

that was how i left it when i gave up

 

[yamahaSHO]

So your trying to make it idle better? How far is the KAMRF correcting? If it is within +/- 5% I would not be concerned. What your looking for is likely injector driven. If it is majorly out of whack, but higher load cruising and OL are fine, you're likely looking at Injector Offset and/or low slope/breakpoint driven.

Have you changed injectors? What are your trims other than idle? Do you hit target AFR at WOT?

 

[Ishodu]

I have seen strange things happen with the car when the maf flow curve was not l going upward when voltage was. Your telling the car that when the voltage goes higher the flow goes lower there at a few points this is no logical. Try setting it back to the original curve and try what Jason has said.

 

[nc89sho]

injectors are stock 3.0 injectors. a/fs at WOT are good, and not much if any correction while cruising. this is only an issue at idle.

that's the correction i'm talking about. and when the car first returns to idle, it is insainly lean for a couple seconds (like 20-1 lean) untill the correction values return to where they were. also, i don't have a good copy of the stock lincoln transfer. anyone have one?

 

[Toolman]

http://www.shonutperformance.com/MarkVIII80.MAF

 

[nc89sho]

also, i was wondering if the +20 cams could be causing some kind of issue here. any recommendations on this?

 

[nc89sho]

ok, so i swapped to josh's 80mm maf transfer and basically added 1.5 to the entire curve. that got me to this:


Seems odd that it's not more of a change though doesn't it?

 

[yamahaSHO]

You went from commanding 11.7-11.8:1 to attain STOICH to 14.2 - 14.5:1 to reach STOICH. That's actually a pretty significant change in the realm of tuning. This is where you start to find tune it to get that extremely drivable car that just runs well.

 

[nc89sho]

the odd thing though is.. the numbers went down, but the Fuel went up?? can someone explain to me why that is?

 

[yamahaSHO]

Yes...

LAMBSE (fuel correction) - This is what the computer is currently commanding based off the commanded AFR's in your map and O2 feedback. IE: If your current settings are hitting 13:1 in CL operation, you will see LAMBSE command somthing like 17:1 to bring the car back to STOICH per O2 feedback.

KAMRF (fuel learning)- These are your fuel trims over time. As these build up, your LAMBSE number will start to try to command actual AFR's per your map.

CLIFFS: LAMBSE is immediate fuel correction until the computer learns these values over time and puts them in the KAMRF.


Also - KAMRF >1 is adding fuel to correct for a lean condition. <1 is reducing fuel.

Example: 1.023 = adding 2.3% more fuel
.985 = reducing 1.5% fuel

 

[nc89sho]

i just don't get how i'm using a smaller aif flow number and getting more fuel.. doesn't make sense. unless it's something with the combination of numbers i was using.

 

[yamahaSHO]

How is the transition compared to before?

 

[nc89sho]

sorry, don't understand what you mean, transition?

 

[nc89sho]

best yet. this is after idling at temp for 5 min

 

[yamahaSHO]

Looks good so far. Drive it a bit and see where it learns new trims.

The transition I was talking about was between voltage points on the curve. As it goes from one voltage to the next, it will draw a line for everything in between.

 

[nc89sho]

Looks good so far. Drive it a bit and see where it learns new trims.

The transition I was talking about was between voltage points on the curve. As it goes from one voltage to the next, it will draw a line for everything in between.

ok, that. this current transfer is pretty smooth. i pretty much changed the whole curve up till i was close at idle, then just tweaked the bottom to dial it in.