t04rx7

Can anyone tell me what the default values are for the air intake temperature correction in the pfc (i.e. pfc adds X% of fuel for this range of temps). I believe the chart is in the datalogit manual, but I lost it and am no longer a member of the e-group. TIA.

es

Default values:
Inj vs: Air temp
+80° = .957
+50° = .984
+30° = 1.012
+10° = 1.055(I'm told this should be bumped to 1.078)
-10° = 1.102
-30° = 1.148

Enjoy,
Eric.

KevinK2

interesting. seems to imply no correction if intake is 40C.

the ideal corrections, normalized to 40C, and % richer the PFC values are:

+80 = 0.887 , +7.9% ... (176F)
+50 = 0.969 , +1.5 ... (122F)
+30 = 1.033 , -2.0 ... (86F)
+10 = 1.106 , -4.6 ... (50F)
-10 = 1.190 , -7.4
-30 = 1.288 , -10.9

richer when hot (stock IC), leaner in very cold conditions.

twokrx7

iTrader: (1)

KevinK2,

That sounds backwards ... adds fuel when intake air is cold and less fuel when intake air is warm,

Kyle

redbase

Actually, it sounds right. Cold air is dense air which means more oxygen molecules per area due to temp. This will cause a lean condition unless more fuel is added.

KevinK2

The raw PFC corrections suggest all the tabled ms values will be used directly at 104F (40C) AIT, and the ms will be modified by this temp correction table if charge temps are above or below 104F. If at 10 psi and 176F (stock IC), the boosted air will be less dense vs the 104F base, so 95.7% of the ms value is used.

I listed the theoreticlly correct temperature correction, and how much richer the PFC default values are.

The PFC provides xtra gas when hot, to avoid knock. For very cold conditions, knock is much less likely, so they lean out the maps more than the theoretically correct compensation .... implies the reference ms tables (104F) have some xtra richness that is not needed in severe cold.

Also means if u dyno to 13:1 with stock IC, peaking at say 176F, then next day install big IC that has max AIT of about 100F, you will now be near 14:1 at max power.

twokrx7

iTrader: (1)

Methinks the correction factors add fuel when intake temps are low and removes fuel when warm ... the ignition correction maps remove timing when intake temps get too toasty.

Badog

Sorry missed this thread when it was still kicking.

Confirmation: adds fuel according as IAT going down. Also think of each temperature setting for the correction factor as points on a line. Graph the points, link the points, you have a 'line.'

The Y-axis is fuel corrections, where 100 = 0 change, 120 = 20% MORE fuel for the X-axis temperature. The MISC line is that of a car I tuner, it may be mine, I'll have to look it up in my database.

Badog

KevinK2

by me: "richer when hot (stock IC), leaner in very cold conditions"

I never said the map added fuel when hot, the above quote is relative to ideal temperature corrections.

>Originally posted by KevinK2
>interesting. seems to imply no correction if intake is >40C.
>NO, THAT IS NOT TRUE

Baddog, per your 'stock' plot, the temp correction at 40C appears to be 1.00, which is no correction?

Badog

Okay, just temperature correction it seems that way. But the PFC transitions between the goal values. While it is therorectially correct that there could be nominal correction at a certain temperature, based on all the correction factors interacting, I don't see it happening that often...even when you're at 40C exactly.

nocab72

Just a FWIW, the stock correction factors DO NOT add enough fuel for cold conditions on highly modified twins, or for any single setup.

They should be fine for stock or lightly modified twin cars.

K

SPOautos

So what temp correction factors are recommended for 380+ rwhp cars???

I've had nights here where my intake temps were -1C to 10C while on the interstate.....and I'm in freakn Alabama lol

I have added a little to them but not much, what are you guys running?

STEPHEN

Badog

Stephen,

Monitor your INJ duty cycle and AFR (if you have it) and you can tell what is going on. As the weather gets colder, you pump more fuel based on the correction factor...so your duty cycles go up to maintain the same AFR.

The MISC correction factors came out of a map from my car. They should be tuned to your car, just like anything else. If you have what is closer to the STOCK values in your car now, you're screwed at cold temps! And you have a car that is tuned for whatever the temps were when it was last tuned. If you use my factors, I get a credit on "tweaked by" line when you talk about who tuned your car!!!

SPOautos

HaHa, yea I think its the same as what you had in there which being in Ohio I'm sure its pleanty. My a/f's have been good....I keep it on all the time. They are just a hair leaner BUT still in the safe zone.

STEPHEN