I'M LOST!!! 1994 Mustang GT help!

mustang1994 · May 1, 2009

First off I added 24lbs to my stang cause my 19lbs busted, and I had free 24lbs. So the car is running HORRIBLE!!! Won't keep an idle, backfires, runs sluggish, won't run like a stang should.

SO! this is what I did. I put new spark plugs, new wires, new coil, new cap and rotor, tried messing with the timing, put a new IAC, new TPS, added a NEW stange 2 chip to let the computer read it's getting 24lbs injectors, new cold air intake, reset the computer, put 2 new universal O2 sensors, and still BAFFLED!!! HELP!!!

Venom351R · May 1, 2009

Your mass air meter and your injectors now do not match. Your mass air is programed for #19's and the ECU still thinks there are #19's in the car.

mustang1994 · May 1, 2009

The chip fixed that, the guy who programmed to tell the computer I have 24lbs', said I must have the MAF stock.

HISSIN50 · May 1, 2009

Is your EGR stuck open?

What codes do you get?

mustang1994 · May 1, 2009

HISSIN50 said:
Is your EGR stuck open?

What codes do you get?

Oh I got a new EGR valve, but get my new computer scanner soon. Hope someone had a clue.

KamiKaziDK · May 1, 2009

where did you get this "stage 2 chip" from??? and how much did it cost you? Doesn't sound legit to me....but I could be wrong. Did you check ALL your vacuum connections?

BlownFiveLiter · May 1, 2009

This stage 2 chip is suspect, IMO. What was "busted" about the 19lb injectors?

mustang1994 · May 1, 2009

Wouldnt fire up

sledge42hammer · May 1, 2009

+1 on the chip sounding like BS. and you need to replace MAF. its cheap and easy. if your going to fix it. do it right.

Stanger007 · May 2, 2009

Pull those codes and see what is going on there - something is definitely not right to be running that badly.

How does it run with the chip off?

Wes

Black95GT_Kid · May 2, 2009

Ive never heard of tuning the ECU to compensate for the MAF and working properly. I would start with a new MAF, and go from there.

79'293stang · May 2, 2009

From my understanding, all the MAF's are the same between the v6 through the Cobra. Cobra runs 24s on the same maf. Ford as far as I know tunes the ecu for the different injectors. I am sure there is someone who will back me up on this since there are about a hundred posts arguing this fact!

BlownFiveLiter · May 2, 2009

79'293stang said:
From my understanding, all the MAF's are the same between the v6 through the Cobra. Cobra runs 24s on the same maf. Ford as far as I know tunes the ecu for the different injectors. I am sure there is someone who will back me up on this since there are about a hundred posts arguing this fact!

You're correct on how Ford tuned the EEC for the injectors.

mustang1994 - Did you swap out the 19's for 24's because the car wouldn't fire, and that's how the assumption that the injectors were bad was made? I ask because this post was a bit vague and I'm hoping we can find you the answer you need:

mustang1994 said:
Wouldnt fire up

99FiveOh · May 2, 2009

Black95GT_Kid said:
Ive never heard of tuning the ECU to compensate for the MAF and working properly. I would start with a new MAF, and go from there.

Are you kidding? In this case we could NEVER get the Lightning MAF's to work on our cars! And even if he does get the correct MAF, in this day and age getting one that's spot on isn't guaranteed. Thus, we have to get them "fine tuned" to play nice with our injectors!

KamiKaziDK · May 3, 2009

He kinda skipped my questions too.....that chip still sounds shady to me

99FiveOh · May 3, 2009

It seems as though the bigger the injector the more tuning issues you have with "matching" MAF's. 24lbers and a nice Pro M should work well together. My .02

final5-0 · May 3, 2009

The_Mustang said:
It seems as though the bigger the injector the more tuning issues you have with "matching" MAF's. 24lbers and a nice Pro M should work well together. My .02

The reason is really simple if you look at the big picture

The whole idea of a meter that reports false airflow readings to the pcm
so one can use larger sized injectors is so inferior to tuning by adjusting
the pcm parameters.

Two things become quickly apparent with using that method with the
intent of avoiding a tune of the pcm

1) Your load factors get all hosed up
and
Unlike the older Fox pcms which are RPM based

Our 94-95 pcms are LOAD based
so
If your load is not accurate

The pcm can't deliver the correct amount of fuel and spark

2) At low pulse width driving conditions, (idle & cruise) larger sized injectors
deliver too much fuel which can easily be corrected by optimizing the pcm.

Of course ... When one trys to use the cheat method of the meter reporting
false airflow to the pcm and no tune is in place, you end up being too rich
at idle and cruise

A meter caled for 24's is not gonna be accurate
but
The amount of inaccuracy isn't enough to make things unbearable

Well ... most of the time

Bottom line here is .....

For our Stangs ... the load needs to be accurate :Word:
and
If the meter is outta whack because one got larger injectors
well
You stand a good chance of dealing with drivability issues

Thats the thing about a tune

You can get all that inaccurate junk in the pcm back in proper perspective
so it works with ... NOT ... against all your hot rod parts

Grady

shttygtstang · May 7, 2009

Well its pretty ovious as i see your injectores were fine . Pull em out along with the chip and find the real problem .
Ide see what fuel preusure is at the intake the make sure your Fpr is ok.

I'M LOST!!! 1994 Mustang GT help!

mustang1994

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