supercharged 5.0 l
 

i have a 91 mustang gt with bbk underdrive pullys,70mm throttle body,bbk shorty headers,off road hpipe,flowmasters,cold air induction,cobra intake,30lp injectors 190 intank fuel pump,3;73 gears,. i just installed a powerdyne 9psi supercharger.now i am having trouble with the car not wanting to idle. it will start and run great but when left to idle it goes from 1100rpm down to 400rpm back and forth until it shuts off. called powerdyne even took to a ford mastertech cannot find a problem.any ideas would be greatly appreciated.

You need some heads....

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1989 GT, 3:55's, full exhaust, 4 in. hood, Pro 5.0, Have many other parts 4 sale. All parts for sale now.

2000 Camaro SS-A4, 13.7's bone stock.

1989 Chevy S-10, EX. Cab-383(500+hp on motor), trick flow heads, trick flow pistons, etc... autometer phantom gauges, "built" 700R4, roll cage, lexan back window, corbeau seats, R.H.S. 5 harnesses, Fuel cell, convo pro wheels, 15x14's with 29x18.5 M/T'S on back, 15x4's on front, nitrous, and so much more!

your heads have nothing to do with your surging idle
you may be a little over injected, i'd probably go with 24lbers with your setup unless your planning on some heads soon
i don't see a MAF on your list so if you have the stock one, GET RID OF IT, im sure thats whats causing your idle problems,
another thing is, if you put the injectors in at the time of the supercharger install and you still have the stock MAF, it wont work right because the stock one is calibrated for stock 19lb injectors

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88 Notch, B&M Ripper, 3.73's, Ported E7's, Explorer int. w/ ported lower, pulleys, 1.7RR's, BBK headers, off-road H-pipe, flowmasters, subframes, 65mm TB, March ram air ,MSD coil, U/L control arms, 155lph f/p, Crane Adj.FPR, Nitto drag radials, best 1/4--> 13.76@101.4 on a 2.17 60ft

It's not the stock MAF that's calibrated for them, it's the EEC as I understand it... right?

The 30lb inj. should be OK for you. They may be a little overkill without heads and cam but the EEC should accomodate them. I've run my car without the supercharger on them without problems.

If you don't have a MAS calibrated for 30lb injectors, you will have problems like you described. Otherwise check that all vacumm lines are hooked up properly.

Do you have a bypass valve and FMU?

Al

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95 GT, GT40 Aluminum Heads, Intake u/l, 9# Powerdyne SC, 65 mm FMS TB, 70 mm FMS MAS, 30 lb injectors, E303 cam, Hooker Super Comp equal shorty headers, H pipe, Flows, Nitto DR, MSD BTM, Adjustable FP reg, 255 fuel pump, Autometer gauge pod with Electric FP guage and Boost guage, a few other odds and ends

FiveOhPatrol is correct, MAF's are calibrated to injector size.

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Todd
1995GT Cobra look-alike
pulleys; Flowmaster cat-back; 65mm TB; Cobra R's, front, and wing; FMS aluminum driveshaft, Mac off-road H pipe
e-mail: todd5874@bellsouth.net

You need a good set of heads, a nice cam, and about a 73-77mm MAF! Normally I don't think the heads would be the problem on a NA car, but w/ that blower, I think it just might be!

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'90 LX 5.0;12K original miles (no sh*&);3.55 gears; March pulleys;Edelbrock Performer Heads;BBK 1 5/8" equal length shorties;MSD 6AL ignition w/ blaster 2 coil;FMS E303 cam;Pro-M 75mm MAF;BBK 70mm TB; Eibach drag-launch spring kit;Southside welded subs;9" K&N cone filter charger;Hurst shifter;Cervini's 3" turbo hood;A/C delete; gutted cats;2 chamber Flomasters;Corbeau racing seats;FMS 30# injectors;JMS chip; Holley 190lb fp;TFS track heat Intake (12.299 @ 113 - 1.78 60')