• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech

will sct chip help?

  • Thread starter Thread starter 93lxSaleenclone
  • Start date Start date Oct 16, 2011
Prev
  • 1
  • 2
First Prev 2 of 2

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,265
17,952
224
Massachusetts
Oct 18, 2011
#21
  • Oct 18, 2011
  • #21
I think with your mods, you do need the 24# injectors, but without a chip, or a proper MAF, I'm not convinced the combo is correctly tuned for them. I've seen cars run "fine" without proper injector calibration, but it might not be ideal. The o2 sensors would inform the computer to just shorten the pulse width way down and you would lower the fuel pressure. Is there an adjustable fuel pressure regulator? If so, I bet it's set under 39psi?

It could be loading up on fuel causing your idle issues.

Run your codes...I'm curious what comes up.
 

93lxSaleenclone

Member
Sep 23, 2011
42
0
6
St. Pete
Oct 18, 2011
#22
  • Oct 18, 2011
  • #22
No adjustable fuel pressure regulator. Actually my fuel pressure guage is pegged out but i havent got to check it out yet. It was that way when i got it. I pull codes tomorrow and post back
 

vristang

15 Year Member
Mar 31, 2005
4,933
101
124
Seattle
Oct 18, 2011
#23
  • Oct 18, 2011
  • #23
You have a fuel psi gauge, but not an AFPR?

Pull your codes, as already suggested...



Maryland Stang said:
I'd be willing to bet money that if you were to put 19 lb injectors in the car it would idle and run perfectly.
Click to expand...
Not with a 93 Cobra MAF it wouldn't...

Maryland Stang said:
Get a MAF housing that's calibrated for 24 pound injectors and put your Cobra sensor into it. I bet that fixes it too.
Click to expand...
Not with an A9*/A3M series computer...

Either combination might get the car to run, but it wouldn't be right... you would be relying on the Adaptive Strategy to get the car running decent.
 

stanger9410

Member
Jul 18, 2011
88
3
19
plymouth, in
Oct 19, 2011
#24
  • Oct 19, 2011
  • #24
93lxSaleenclone said:
Other than at idle do you feel it ran worse than before you installed the chip?
Click to expand...

it ran better after the chip, it idled correctly and i wasnt losing power on the top end. it was a good use of $300
 

93lxSaleenclone

Member
Sep 23, 2011
42
0
6
St. Pete
Oct 19, 2011
#25
  • Oct 19, 2011
  • #25
I tested the wires to the IAC with my meter and got 14.49 to engine ground and 13.44 to return wire/computer ground. So I assume thats working properly?

Pulled codes and got these.
engine off codes:
33

engine on codes:
21
94
44
33

I still get no change in idle when I remove the plug to the IAC. Although it idles perfectly when I started it to warm it up to do the tests.
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,265
17,952
224
Massachusetts
Oct 19, 2011
#26
  • Oct 19, 2011
  • #26
Well, the idle should change really. At idle, the ac should be closed, or pretty close to it.

When you pull the plug out, if the ac if full closed, nothing should change.

When you ran the engine codes, did the engine idle up?

Try this. Get the engine warm and toasty and unplug the iac. Now, back out the engine throttle stop screw and back the idle down. Get it to the point where the engine is about to stall. Then shut it off, plug the iac back in and reset the computer by unplugging it for 15 mins. That should reset idle.

Now, the lack of iac codes suggests the idle screw is set too far in keeping the iac closed most of the time. Back it down and see if that changes anything.

Honestly, I think the iac issue is a bandaid for the injector mismatch. Im assuming a lot here but i bet The idle was probably poor, so the idle screw was opened a bit to keep a steady idle forcing the iac to remain closed to try and lower the idle. You might have idle issues as you lower the idle down.

Typically if the iac is not working right, you get two codes.

Edit: ok, there is a few, but the one I was specifically looking for was 36/37 which is the computers inability to raise idle during the koer sequence. The lack of that code suggests the iac was able to raise the idle during the test.

Again, I'm not there so I'm taking an educated guess
 

93lxSaleenclone

Member
Sep 23, 2011
42
0
6
St. Pete
Oct 19, 2011
#27
  • Oct 19, 2011
  • #27
Yes the idle raised during the test. When I set the idle again a few days ago I did it with the iac unplugged to begin with. I set it around 800 where it seems like a good idle (sound wise) then plugged the IAC back in, reset computer and thats where I am at now. When I start the car cold it idles around 1400 for about 15 seconds then drops back to around 850 and stays there. When warm I sometimes get the surge for about 15 seconds then drops back to 850 and stays there. It is still running great. Excellent throttle response with no hesitation what so ever.
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,265
17,952
224
Massachusetts
Oct 19, 2011
#28
  • Oct 19, 2011
  • #28
So it raises idle during the test and no iac codes?

Iac is fine.
 

93lxSaleenclone

Member
Sep 23, 2011
42
0
6
St. Pete
Oct 19, 2011
#29
  • Oct 19, 2011
  • #29
Im going to take a couple videos of my idle tomorrow and post them. Maybe i'm just looking at it too much. Its not actually causing any driveability issues.
 
2

2002BLGT

Well-Known Member
Dec 18, 2003
2,945
4
59
Bedford VA
Oct 19, 2011
#30
  • Oct 19, 2011
  • #30
With the Cobra MAF and 24lbs injectors , the easiest and fastest 2 ways to fix it would be to locate a X3Z computer which would be expensive or get a chip and use the X3Z.bin file for a startup file and modify it from there , this will get it 95 percent right off the bat .....
 
2

2002BLGT

Well-Known Member
Dec 18, 2003
2,945
4
59
Bedford VA
Oct 19, 2011
#31
  • Oct 19, 2011
  • #31
93lxSaleenclone said:
No adjustable fuel pressure regulator. Actually my fuel pressure guage is pegged out but i havent got to check it out yet. It was that way when i got it. I pull codes tomorrow and post back
Click to expand...

If your fuel pressure is pegged high at near 80psi then you have a pinched return line back at the fuel tank , I have seen this a few times when people install new fuel pumps they pinch the line between the tank and the body of the car
 

93lxSaleenclone

Member
Sep 23, 2011
42
0
6
St. Pete
Oct 20, 2011
#32
  • Oct 20, 2011
  • #32
Ill check the return. In the mean time are any of the codes a cause for concern?
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,265
17,952
224
Massachusetts
Oct 20, 2011
#33
  • Oct 20, 2011
  • #33
33 is an EGR code. you def want to look at that.

Code 21...was the engine fully warmed up when you ran the KEOR test? If so, this indicates a potential bad ECT.

Run the test with the engine nice and hot. If the code 21 is still in the Engine Running codes, time to check and maybe replace the ECT
 

93lxSaleenclone

Member
Sep 23, 2011
42
0
6
St. Pete
Oct 20, 2011
#34
  • Oct 20, 2011
  • #34
Anything specific to look at at the egr? The car was probably at about 150 when i checked the codes so it was fully warmed up.
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,265
17,952
224
Massachusetts
Oct 20, 2011
#35
  • Oct 20, 2011
  • #35
150 is kinda cold. Should be up in the 180-190 range. Does it get hotter than 150?

Code 21 (the ECT) sensor is a sensor you definitely want to make sure is working correctly. It will cause flooding issues and hard starting when it goes bad
 

93lxSaleenclone

Member
Sep 23, 2011
42
0
6
St. Pete
Oct 20, 2011
#36
  • Oct 20, 2011
  • #36
Yes it gets to 180 to 190. I just didnt let it run that long before hand.
 

93lxSaleenclone

Member
Sep 23, 2011
42
0
6
St. Pete
Nov 19, 2011
#37
  • Nov 19, 2011
  • #37
Just wanted to post and update...
I got a Moates chip from Willy at dirty dirty racing and it now idles like it should. I'm happy to finally get rid of the annoying surging idle. His customer service was great also.
 
Prev
  • 1
  • 2
First Prev 2 of 2
You must log in or register to reply here.

Similar threads

7
Engine Random hanging idle
  • 706 Saleen
  • Feb 11, 2026
  • Fox 5.0 Mustang Tech
Replies
9
Views
674
Fox 5.0 Mustang Tech Feb 19, 2026
86HO5.0
8
9
Engine Donor '00 Mountaineer meet '91 Fox
  • 91firecracker
  • May 11, 2026
  • Fox 5.0 Mustang Tech
  • 2 3
Replies
41
Views
936
Fox 5.0 Mustang Tech May 28, 2026
91firecracker
9
C
03 Cobra Low Fuel Pressure
  • CTsnake_03
  • Mar 17, 2026
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
5
Views
281
1996 - 2004 SN95 Mustang -General/Talk- Mar 24, 2026
CTsnake_03
C
1
Engine 91 mustang 302 Low acceleration car backfires pops and acts like it doesn’t want to take fuel
  • 1991Fox5.0
  • Oct 4, 2025
  • Fox 5.0 Mustang Tech
Replies
16
Views
1K
Fox 5.0 Mustang Tech Oct 6, 2025
1991Fox5.0
1
T
  • Locked
Digital Tuning A9l issue or something else
  • Tufgriz
  • Sep 11, 2025
  • Fox 5.0 Mustang Tech
Replies
2
Views
294
Fox 5.0 Mustang Tech Sep 11, 2025
Noobz347
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?