STUMPED

[1HOT5L]

Has anyone seen a mustang run fine at idle, bogs at wot, pulls hard at 3/4 throttle, leans out and backfires at part throttle. New 190lph pump, new adj fuel pressur reg, new tps, cleaned IAC, new bosch +4 platinums, new cap rotor and wires. Fuel pressure steady at whatever I set it at, tried 38 - 55 psi no change.Tried 2 new mass airs. New o2 sensors

Car=1988 gt convert
mods:bbk equal 1 5/8, bbk x, amer thunder catback, 1.7 rr, pulley's, mass air conversion(1989 eec), 75mm granatelli mass air, black magic elec fan, cai, typhoon intake, zex dry kit, 100 amp alt, aurora ign, autometer gauges, mach 1 hood, 75mm tb, strut brace, sub frames, eibach springs, ripper shifter, adj clutch cable & new billet quadrant, dual fric centerforce clutch,

 

[proxses]

Vacuum leak
That sounds quite strange. It says you have tried 2 meters. Was one of them a stock meter?
Also, have you thought of bypassing that aurora ign, to see if it is having some troubles?

 

[1HOT5L]

I am ordering a new ignition as I am writing this, good call on the stock mass air, both I have tried have been new after markets, could I have 2 bad mass airs?Vacuum does seem a bit low, tried to find it with the old carb cleaner trick and found nothing, timing is at 8 deg for the nitrious

 

[proxses]

The aftermarkets may not have been calibrated properly for your application.
Are you still running the stock injectors? If so, find a stock meter and try it out.
As for the vacuum problem, all I can say is keep looking until you are satisfied. They are a pain to find.

 

[noslow5_0]

PLATINUM PLUGS ARE CRAP!!!! get those damn things outta there a.s.a.p.!!! platinum doesnt conduct near as good as cooper, and all those other prongs are just there for looks... elec. will fallow the path of less resistance, which would only lead it to fire on one of those prongs!! go get a stock set of plugs gapped at .5 an you will be good to go!! I had the same problem with mine for about 6 months not realizing there was platinum plugs in it!!! Give it a try since stock motorcraft plugs are only like 1.75 a pop!!! good luck!!

 

[1HOT5L]

I thought with no2 you should run a plug with a larger ground strap so it doesn't melt off

 

[TheUser]

I had a similar problem and it was because my timing was around 8*...bumped it up to 12 and runs much better.

 

[GTRocks]

Clean your MAF. At the top of your MAF on the inside there are two small wires that hang down. Particularly if you have a CAI, impurities settle on these wires. They are used to sense airflow and in turn the computer uses that input to determine air/fuel mix. If they are not clean, the computer screws up the air/fuel mix and it can (and did in my case) cause backfiring. Clean them with a Q-tip and carb cleaner, very gently (if you snap them, you'll be buying a new MAF). Get all the crud off of them and you'll pick up 25 horses!