2005 Saleen - lean issue

[kjlindgr]

Hey all. I have a 2005 Saleen S281 (supercharged), fairly stock, with a lean issue under load that I can't seem to resolve. Tune/log attached is from an open loop run. Right at about 3.0V on the MAF, you can see it pull injector pulse width and eventually drifts lean. Ahead of that it's pretty much right on target. Doesn't matter how much I swing the MAF fueling up in that area, it still is lean.

There is also a really goofy blip in the "mass airflow" signal in this area (see picture below). No idea why this is tweaking out if the MAF voltage is stable???

Fuel pump is keeping up just fine - it's a 450lph pump. Injectors are 600's out of a Hellcat which should be plenty. Only expect the car would make about 500hp.

Can anyone help to see what I might be missing?

lean2.png

run7.hpl
RESCALE_OL_FAIL_0013.hpt

[kjlindgr]

It seems weird that the voltage doesn't fluctuate much yet the mass airflow calculation swings so wildly.

2.99V is calculating 83 lb/min
3.01V is calculating 14.6 lb/min
3.02V is calculating 48.4 lb/min

Does anyone know what, aside from MAF voltage, plays into this mass airflow calculation?

[MaximumVelocity]

Id use a well known injector that has data for ford pcm. Also that tune needs lots of work...Did you start from a stock saleen tune?

[aaronson]

Buy some LU-47lb injectors. Use the timing off a 2008 gt500 as a good base. There should be some in the repository. usually lean spikes mean that you are running out of fuel.

[aaronson]

also that dip in the maf #/min can be attribute to the car limiting airflow by closing the throttle.

[Witt]

calcmapmax.jpg

Try recalibrating this to the appropriate value.

[nicks1031]

This is your MAF curve, it does not look good.

3V MAF Curve.PNG

You can see exactly where your MAF Volts hits 2.88 in the log and then sky rockets. This curve should be smooth. The other major part in the load/fueling equation is injector data. You cannot fudge injector data in Ford ECUs, this is probably where you're only seeing air load never go over 1.2 which would equal something like 3lb of boost.

+1 on getting some injectors with proven data.

[kjlindgr]

Thanks guys. I have that big blip in the MAF curve as I was trying to get it to dump fuel in. I did update the CALC MAP MAX value and the mass airflow calculation seems to have corrected itself. Still running into lean issues up top where it just won't command more than 13ms of pulse width. I guess it's time to get some different injectors?

[nicks1031]

Thanks guys. I have that big blip in the MAF curve as I was trying to get it to dump fuel in. I did update the CALC MAP MAX value and the mass airflow calculation seems to have corrected itself. Still running into lean issues up top where it just won't command more than 13ms of pulse width. I guess it's time to get some different injectors?

Definitely get some injectors with known data, DM me and I may be able to help you out.

[sportinawoody]

ummm anything over 64 lb/min in that GT spanish oak processor, the ecm will not compensate for. i dont think these have the 86lb ceiling but i could be wrong on that. either way youre reporting to much airfrom the maf. you have to scale your injectors, displacement, manifold volume, maf and a few other things.
whats happening is youre exceeding the pcm's ceiling for the maf and the pcm is freaking out

[kjlindgr]

Thanks for all the help everyone. Is there a write-up of what may need to be changed if I need to go down the route of rescaling?