Anything about Ford EEC tuning. TwEECer and Moates questions dominate, but there's some SCT and OBD-II knowledge too.

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bgblkstang
Gear Head
Posts: 19
Joined: Thu Jul 30, 2009 11:25 am

Lean after tip in

Post by bgblkstang » Tue Aug 24, 2010 2:10 pm

Ok so I'm havin the classic lean spike just after tip in issue. Basically what happens is when I accelerate a/f goes plenty rich like it should but just after it does it will immediately spike lean (around 16.5) for a split second then level off to stoich. most times this does not cause a stumble but sometimes it does. Seems to only do it on light accels not wot. Now I can't datalog only have a wideband to go off of. I read thru this forum and I understand it most likely has to do with transient fueling and/or accel enrichment. The problem is I'm not sure which way to adjust these numbers. I've read it could be too much enrichment causing CL to pull too much fuel and overshoot or I maybe I need more enrichment. Any suggestions?
Forged 306 ported edelbrock heads, ported typhoon intake,70mm throttle body, 80mm lmaf, 24lb injectors, trick flow stage 2, mac long tubes, full exhaust a9l/x3z base, moates chip

decipha

Re: Lean after tip in

Post by decipha » Tue Aug 24, 2010 8:19 pm

what makes you think your afr should go plenty rich on tip in?

it's best to tip in a tad lean for enhanced throttle response, if you tip in rich then the hego's are probably pullin' to much fuel and then once they pulled fuel you level out and the hego's are already ramped lean so comes the stumble

force open loop clear the kam's and get your fuel situated first

when dealing with the gufx ecu's i disable accel enrichment and use just transients, just like in the newer ecu's

set "aem" to 0 then go 0 out fn1303
set decel enrichment "tefmrd" to 0
set "meftra" to 1 so you get the values in the table
"tfcded" to 2% so transients step in sooner
"mteftc" to 1 so you get the values in the table

then go to fn1321 and take all the values at 150 and divide it by 2 then copy those values to the whole table

that won't be exact but should be close enough to get you going, you'll need to play with the transient tables to get your desired results

you'll be probably messing around in fn1351 the most, you may even find that you may need to rescale the table to get more control where you want it, not usually but if your anal about it, just depends on how much you want to 'perfect' it

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