MAF seems way out after VE table tuned.
02-03-2008, 03:43 PM
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MAF seems way out after VE table tuned. Placed the car in OLSD and edited the VE table against AFR error, was within +/- 2 around most of the board. Idles at 14.7 and cruises around between 15.0-15.5. Plugged the MAF back in and reset the fault Hz back to stock and was looking at +18 actual AFR in the cruise cells. So I scaled the entire MAF table from where it started all the way up to the top by +30%. Uploaded the tune and ran again, a little better but still lean as I got on the throttle. Any ideas? I am at work right now so I cannot obtain my tune or scan. Tuning software - HPTuners. WB - PLX. Should I look into some WOT tuning with my VE table and make sure that is spot on as well, what else could cause readings to be so far out of the norm?
02-03-2008, 07:26 PM
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The "VE tune" tweaks the -whole assembly- in to stoich /
minimum AFR error. But if you have any fuel-side error in
the system (fuel pressure off "ideal", etc.) you will "embed"
that error into the VE table by tuning it. The MAF, he don't
know nothing but what air goes by. And the system still does
not know there is a fuel error. So true air (MAF) makes bent
AFR.
I'd check fuel pressure at the rail and see whether it's close
to the nominal 58PSI. I know my car was idling at about 50
last time I checked. You have to tune for what you've got
but if you are away from factory fuel pressure you may have
a good reason to adjust the fuel tables instead of crutching
it in the air tables.
minimum AFR error. But if you have any fuel-side error in
the system (fuel pressure off "ideal", etc.) you will "embed"
that error into the VE table by tuning it. The MAF, he don't
know nothing but what air goes by. And the system still does
not know there is a fuel error. So true air (MAF) makes bent
AFR.
I'd check fuel pressure at the rail and see whether it's close
to the nominal 58PSI. I know my car was idling at about 50
last time I checked. You have to tune for what you've got
but if you are away from factory fuel pressure you may have
a good reason to adjust the fuel tables instead of crutching
it in the air tables.
02-03-2008, 08:38 PM
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So if I place a pressure gauge on the rail at idle would that be sufficient enough to determine fuel supply or would I have to monitor it under a load as well. I ask because I have a 0-60 gauge that I can place onto a shrader fitting but it is a bit difficult to view when driving while attached directly to the rail. :/
02-04-2008, 02:52 PM
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I'd put the mechanical gauge to it, and watch at idle
(min fuel flow, should be your highest reading) and on
the brake with as much throttle as you can hold, just
to get an idea if it's varying.
Being as you're "pressurized" does that mean forced
induction and if so is there a manifold-referenced fuel
pressure regulator? That would be a whole 'nother game.
(min fuel flow, should be your highest reading) and on
the brake with as much throttle as you can hold, just
to get an idea if it's varying.
Being as you're "pressurized" does that mean forced
induction and if so is there a manifold-referenced fuel
pressure regulator? That would be a whole 'nother game.