cnechs

I have a 1989 mustang gt with the 5.0 liter. for the past few months ive been trying to figure out why i keep getting a code 66 (mass air flow sensor) when we ran the KOER test. we originally got a new mass air sensor but when we plugged it in the car wouldnt even run. i am having to drve ie with it unplugged. it drives for the most part all right but seems to "backfire" and idles off. when its plugged in there is entire loss of power it wont idle for a dam and dies out. you cant go anywhere. when i bought the car a couple years ago it had an air intake ( from the throddle body down) that was "rigged" together. the mass air flow housing thats on it now is made by Pro M. and it looks to be way too big for the car.
If i replace the air flow system from the throttle body back to factory including the mass air flow sensor and housing if this will fix it.

thanks in advance!
chris

TrimDrip

the meter is cal'd for your injectors?

steelie4u

I was there looking at the car with him, looks like the previous owner rigged a cold air intake and replaced the mass flow sensor and housing with one made by PRO M. have no idea what size it is but the housing unit is twice the size of the original. I was thinking if he replaces that PRO M with a stock one that it may fix it, only upgrades are cobra lower intake and it looks like a BBK upper intake,, im not sure so thats why were asking, took the black sensor off a BRAND NEW mass air flow unit and put it on the PRO M and it wont run, is it possible that that the MAF sensor and the housing dont match( calibrated) and this whats causing the problem? the only code it throws are 66 for the MAF. checked all wiring to the computer and connectors and all check out, even replaced the computer and still same thing.

toms93lx

i would put the factory air cleaner and tubing on and then unhook the battery for an hour then hook the batery up and start it.......if it idles let it sit there for 5 minutes just idleing to set the computer.........i had a similar problem ......i took off the factory air box and put on a bullet filter and it did not run as good as it did with the factory air box.......created idle issues......been running the factory set up since........

TrimDrip

The MAf doesn't have to match the throttle body size.

Also, the Pro-M sensor should say 19lb on it.

If you have a stock meter, try that too.

cnechs

thanks guys im gonna take her back to factory air and see what happens. il post as soon as we can dig into it further.
im also getting a whistling sound from what sounds like inside the block. it never happened until we started working on these mass air problems. let me know if anyone has an input on that whistling..
thanks in advance.
chris

cnechs

ok so when i originally thought the mass air sensor was the problem i got a reman one from autozone for a 1989 gt(thats the car i have) BUT now that i look at the old one that was on this pro m intake, it says right on the sensor "ProFlow" not FORD like the reman one i just bought. the old one from proflow looks almost like it was specially calibrated though. should i get a whole new factory air from the throttle body down, to try to fix the problem, or should i get on the internet and try to order this exact same sensor from proflow? one of you said it should run better with factory air but this intakes been on this car from before i bought it a year ago..
anyways thanks again ahead of time if you have any idess.
-Chris

TrimDrip

if your injectors are an orange color the factory maf should work.

the car has ran good the cal'd meter in the past so you may want to go that route.

make sure the factory maf is not smaller than the throttle body.

for the whistle, check the pcv valve to see if it hasn't popped out.

zebo87

i have the whistling thing and seems like the same prob now. the only diff is it runs at about 75% when warm. i cleaned the iac last week and the whistling has not come back since. my maf is calibrated for my injectors though. the only thing i havent done is run codes or checked the maf tube to see if the sensor is still intact.

xxxmustangtxhc

i had the same problem with my gf car i got the right mass air for it and havent habd a problem since