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Discussion Starter · #1 ·
I just rebuilt a 351w for my 96 MAF Bronco. Stock compression, GT40 heads, 1.7 rockers, small Compcams roller, shorty headers and an edelbrock intake. Truck runs really nicely and pulls very well up to 3000 rpm or so, where is seems to falter/flatspot briefly before resuming acceleration. It almost feels like a slipping clutch in a manual but instead of allowing hte motor to rev, while deceleration slows, rpm's gather more slowly.

LTFT's look good. Short terms due the typical FORD thing where they are too rich at light cruise and then get quite lean as rev's build. What is odd is that it does seem to improve after that bit of a flat spot. i am left wondering if this is in the tuning (pointing at a wrong spot in the load/fuel tables) or tranny related.

as an aside, o2's seem fine, Maf shows smooth outputs. TPS never shows above 94% on my OBD 2 real time dongle...since its impossible to get to, i''ll replace it rather than just adjust, but not sure if this could be part of my issue.

in any case, open to the wizardly input from the board.
 

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85 Bronco, 309ci I6 w/4bbl, np435, 4" lift, 37" Irok NDs, 4.56 w/ Detroit Locker and tru trac
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TPS seems logical. As does new O2 sensors. What cam are you running?
 

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Discussion Starter · #3 ·
The o2s produce good voltage and dither correctly. That's not it. Cam is a very mild comp cams. Roller.

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What’s the timing doing before, through and after the flat spot? What load and TPS when testing?
 
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