Changed Clt & mat bias res, now rich

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millhouse
Helpful Squirter
Posts: 50
Joined: Wed Mar 22, 2006 9:28 am

Changed Clt & mat bias res, now rich

Post by millhouse »

I am running msns-e 029q with megatune v2.25 on a v3 main board.

The car…my 5.0l twin turbo mustang with mods as seen in my sig below.

Now...I had used easytherm with the temp. and resis. settings per http://fordfuelinjection.com/index.php?p=28 (50, 158 & 302)

Now...with those settings and my stock ford sensors, my clt & mat readings were ~ 10*F off cold...and seemed way to high with the engine warmed up. My coolant was reading ~30*F higher than my autometer gauge. I went ahead and tuned my lower VE table with the above mentioned settings...but the temp thing was bugging me.

So....off to radio shack I went and I picked up some 33k resistors (closest to 27k they had). I went ahead and installed them in place of r4 and r7. Next up I went back into easytherm and I used all default settings for the gm sensors.

Now...I had no idea this would effect my tune so much...but I fouled out my plugs in no time. I went from ~ 13.5 afr at idle down to 10.5 (yikes). My coolant temp however now almost exactly matches my autometer setup....and on a rested heat soaked engine my coolant and mat temp's were within 3-5*F of one another.

Was that supposed to happen? I already had a decently tuned VE table and am now wondering if scaling the VE table to the new req-fuel settings is going to cut it.

Any and all help would be appreciated.
1989 lx 5.0 (notch)
twin .60/.48 turbos, 42lb injectors, tfs heads, f303 cam, 255 in-tank pump, 24x12x3 intercooler, Edlebrock Performer Intake,
Bernard Fife
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Joined: Mon Feb 16, 2004 3:15 pm

Post by Bernard Fife »

millhouse,

The IAT affects the fuelling directly (except at idle) so fuelling is quite sensitive to it. CLT is used mostly for warm up, but if it is lowering the 'perceived' temp, it makes all the warm-up enrichments effectively higher.

So changing the temperature sensor calibration definitely could (and *should*) affect the fuelling quite a bit. You ought to be able to scale the VE table and adjust the warm-up nbins to compensate, though.

Lance.
millhouse
Helpful Squirter
Posts: 50
Joined: Wed Mar 22, 2006 9:28 am

Post by millhouse »

Thanks lance....that's what I figured, but I just wanted a confirmation. 8)

Hopefully it doesnt throw the shape of my VE table off by to much...and hopefully this will be the last set of plugs I foul out.
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