1990 Mustang LX Vertible
 

Well been a while since i been on here just saying hi to all and sorry i fell off the forums for a few months, anyway...

Just and update the mustang is finally a 5 speed car and i no longer have reverse light or a nss cause i bypassed it but i dont think thats part of the problem

Mods:
96 explorer gt40 motor/heads/upper and lower intake
e303 cam
ford motorsport 24 lb injectors
proflow 76mm 24lb cali. MAF
Mac cai
Mac shorty headers
o/r h-pipe
super 40's dumped
ford motorsport alum. d/s
t-5 with perfection clutch kit and perfection flywheel
Pro 5.0 S/S
underdrive pullies
a/c and smog delete
3.08 gears....and thats everything i can remember off the top of my head

issues: I disconnected the IAC to stop the idle issues but wont hold idle til warmed up and i get only 13 mpg and when i connect the iac it surges so makes driving the car a pita when you shift it revs to like 3 grand.....any ideas on idle issues and why my mpg sucks horribly all started after the injector and cam swap

thanks as usaul ;)

have you tried pulling the iac off and cleaning it with some carb cleaner? it could be dirty and sticking. you could also try swapping it with a new one. is your tps set correctly. after teh car is warmed up and idling on its own, set the idle to about 800rpm at the tb with the iac unplugged. after you get the idle set check your tps make sure its in the .9-.95v area. if not you need to adjust it. once you set the tps unplug the battery for 20min and plug the iac back in. after you hook the battery up start the car and see how it idles. once you do the h/c/i the stock settings almost always get thrown off.

as far as milage goes, have you gone through the basics? making sure fp is correct, o2s are good, maf is clean, plugs are good, quality plug wires, tires fully inflated, etc. have you checked for codes? do you have any? do you drive like a retard? driving style and tire pressure are the two main things in determining mpg unless you have something significally wrong with the motor

its already got a new iac and tps i may have to adjust the tps again, and i tried drivin like a "retard" and a normal hybrid driving human and no difference lol i'll check the tire pressure put a adjustable fuel pressure reg on it may need to adjust it again i dunno but with my modes where should my pressure be about???

plugs cap and rotor and wies all new well couple monts old actually lol

run a koeo and a koer test and see what codes pop up.


clean iac, clean maf, set tps properly and you also need to reset you base idle

make sure no vaccum leaks are present and do a base idle reset

i've also taken apart the intake manifolds and looked at all the vacuum lines still not getting any vacuum at low idle and braking is a real pita hard brakes

is the brake booster diaprahm bad/ruptured/ creating a vaccum leak there??

I hope you get subframes in that limp noodle.

you could have a leak in the gasket between the lower intake and the heads. beleive it or not, somehow mine failed on me over the summer on the #2 runner/port. car had a HUGE vacumn leak, braking was a little hard attimes, car wouldnt idle for crap....

and I tried everything, cleaned every sensor, new o2s... and it was that.