im gunna throw this one at you guys while im here....bear with me.

the red f150 in my avatar.....a couple months ago, i pulled the motor, stock bottom end, edelbrock performer flat tappet cam, used cast iron gt 40 heads, 1.6 roller rockers, edelbrock truck efi intakes, ford racing mass air conversion with the stock 55mm maf, (new water, oil pump, ect...)

anyway the thing runs great! very smooth, definately more power, but i know those intakes and heads and forgot to mention headers and flowmaster are starving through the factory airbox and maf. so i got a 70mm motorcraft maf off ebay, and when i install it, it will idle, but when you try to rap the throttle it pops, and backfires. when you drive it, it backfires under a load. (running lean) checked my fuel pressure....fine.....checked for vaccuum leaks...none.....probed the new maf to make sure it was working...fine

so anyway i put the 55mm maf back on, the top and bottom of the factory airbox back on (basically starved it down a little for air) and the truck runs great. im running stock 19lbers, and i can run it wide open throttle from 0-100 without any problems...

so what should i do to be able to run the 70mm maf and a cone filter? ive got the stock tb and thought about running the bbk 60mm jus so i know i have no restrictions from the filter to the intakes.....from the intakes to the tailpipe im already good (i kinda worked backwards starting with exaust). this is where i dont know if a custom chip,,,or a tuner would be best...


thanks and sorry for the length.....oh i forgot, no cat, no smog pump, and no egr (electrically or physically)

 

What is the 70mm meter from? Just so you know.. the computer is programmed with the transfer function of the 55mm MAF meter, anything else will not produce the correct input for the computer and can be expected to cause problems. The ONLY way to give the computer accurate info with a different meter is with a tuner or custom chip that allows the computer to see the correct MAF transfer function. You can sorta fake it with a meter that has a scaled sample tube, but this still won't produce the best results because a larger meter doesn't just flow more air, it's transfer function has a steeper slope, so everything below WOT will still be off.

 

i know what needs to be done now thanks! that makes sense. i was just looking at sct's mobile tuner website on an older post, and hes located in south carolina too! ill be emailing him. ill post my results when i get it tuned, and put some pics of the engine build in my gallery too.

 

oh the 70mm maf is a factory ford motocraft meter.....i was told its from either a 93-95 lightning, or a 93 cobra mustang

 

Did you get this issue resolved?

 

not yet, in a couple weeks i should have the money. ive been talking to mike at 5star tuning, and hes great! very nice and knowledgable. he said were gunna run it on the dyno, and hell burn a chip for me.

i cant wait to see what kinda difference it makes

 

Put this sign on your dashboard. Get In, Sit Down, Shut Up and HANG ON. It's what I need on mine.

 

It's also possible the meter you got is damaged.. if it was used, have you tested the outputs from the meter?

FWIW I also have a 70mm cobra meter and have used it on my truck with the 5.8. With the Tweecer I entered the MAF transfer function data for this meter and it certainly made a difference to the way the motor idled and performed at low rpms.

 

Conanski how is those tweecers? I've heard about them but I use SCT LiveWire.