Digital Tuning Need help with returning to stock (SCT)

Paradox2018

Member
Oct 9, 2019
21
2
13
19
Pennsylvania
I recently got a 2001 Mustang GT that came with an SCT tune and the tuner itself. For the most part the car runs great, but I get an intermediate P0190 code and the car runs slightly poor while its on... but the code goes away within 24 hours. I want to return the car to stock before I further investigate the problem but I am scared since this is my only car and daily driver.

I have the SCT X3 tuner that was used to put the tune onto the car years ago when the original owner put the tune on, but I have tried connecting the tuner to a laptop and the car for data logging which results in an error in the livewire program. I have NOT attempted to return the car to stock due to the fear of an error occurring.

My question is, can I attempt to return the car to stock using the tuner without worrying about an error during the process? Also, if I would get an error message while returning to stock, is the car not drivable afterwards?
 
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Onesick99GT

Active Member
Nov 20, 2018
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Dayton, Ohio
It depends! If a custom tune was created the file would be saved but returning to stock might delete the tune for good. What mods does the car have first off. How long has this issue been going on? Just started happening ect ect. Btw I am a tuner in case your wondering.
 
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08GT500

Active Member
Jul 12, 2018
460
52
38
Massachusetts
Hi,
Sorry to hear, sympathetic to your plight.
This is how it all works:
Once a Tuner is purchased, it’s “married” to the vehicles Mfg./Model VIN & CPU strategy, as well as the person whom which purchased it, for as long as they own the car.
Transferrin that Tuner as your own, and having it correctly communicate with all your devices is easily done by calling American Muscle, BAMA’s “Tunes for life” transfer to your name, e-mail, address, VIN# costs around 150$, you’re then the registered owner of the device, and can acquire updated tunes as many times as you want, as you add more Bolt-on parts, as long as the Car is still yours, it’s unlimited. Data logging is free as well.
If you didn’t transfer the Tuner over to you, it won’t communicate with your devices, but will not affect what the Tuner has on it already. Can you confirm if you do the transfer, can you please post that before plugging into the car?
You’ll find your laptop will also get along
much better with your CPU
Best!
- John
 

08GT500

Active Member
Jul 12, 2018
460
52
38
Massachusetts
Edit, last paragraph, Can you confirm if you did, or did not transfer the SCTX3 Tuner over to you by speaking to SCT/BAMA
Apologies,
John
 

Paradox2018

Member
Oct 9, 2019
21
2
13
19
Pennsylvania
It depends! If a custom tune was created the file would be saved but returning to stock might delete the tune for good. What mods does the car have first off. How long has this issue been going on? Just started happening ect ect.
I’m not 100% positive on if a custom tune was loaded or if it was one of the preloaded tunes. I’m not worried about the current tune being deleted if it was a custom tune, I’m concerned about if returning to stock fails. Will I be able to drive it still if returning to stock fails?

The mods the previous owner told me are just super basic: k&n CAI, new coil packs, borla exhaust and what he called a “93 octane tune”

The issue has basically been happening since I got the car about a month ago, the previous owner barely drove it the last few years he owned it before I bought it.
 

Paradox2018

Member
Oct 9, 2019
21
2
13
19
Pennsylvania
Hi,
Sorry to hear, sympathetic to your plight.
This is how it all works:
Once a Tuner is purchased, it’s “married” to the vehicles Mfg./Model VIN & CPU strategy, as well as the person whom which purchased it, for as long as they own the car.
Transferrin that Tuner as your own, and having it correctly communicate with all your devices is easily done by calling American Muscle, BAMA’s “Tunes for life” transfer to your name, e-mail, address, VIN# costs around 150$, you’re then the registered owner of the device, and can acquire updated tunes as many times as you want, as you add more Bolt-on parts, as long as the Car is still yours, it’s unlimited. Data logging is free as well.
If you didn’t transfer the Tuner over to you, it won’t communicate with your devices, but will not affect what the Tuner has on it already. Can you confirm if you do the transfer, can you please post that before plugging into the car?
You’ll find your laptop will also get along
much better with your CPU
Best!
- John
It’s the original tuner that was used to tune the car, my concern is that if when I try returning the car to stock and it fails, will I still be able to drive the car?
 

08GT500

Active Member
Jul 12, 2018
460
52
38
Massachusetts
Hi, The only concern with the Mod’s listed would be the CAI. If it’s a canned tune, you should have no issues in reinstalling the same if you need to.
Some require a tune to run correctly, some require no tune. What CAI on installed on the Car?
- John
 

08GT500

Active Member
Jul 12, 2018
460
52
38
Massachusetts
If you have an engine pic, it could easily be picked out if there’s any mods not mentioned by the previous owner that require a Tune, injector colors, etc..
 

Paradox2018

Member
Oct 9, 2019
21
2
13
19
Pennsylvania
Hi, The only concern with the Mod’s listed would be the CAI. If it’s a canned tune, you should have no issues in reinstalling the same if you need to.
Some require a tune to run correctly, some require no tune. What CAI on installed on the Car?
- John
I’m not 100% sure of the model name/number but I know it’s a K&N CAI
 

08GT500

Active Member
Jul 12, 2018
460
52
38
Massachusetts
Hi, EV-1 19lb injectors for GT’s 01’, 02’-03’ went 21lb, MAF calibration delegates size. Don’t have Longtubeheaders- right? I took the I make & am zooming in closer. Is there a Pony on the top of your Throttle body? That’s OE.
I’ll brb, looking at zoomed pic..
-John
 

Paradox2018

Member
Oct 9, 2019
21
2
13
19
Pennsylvania
:nice:
Sent a PM, just FYI
I don’t see any pm from you but it’s dark outside and I’m in bed for the night so I’m not 100% certain but I’m pretty sure there is a pony on the throttle body. Not too much has been modified according to the previous owner

He wasn’t too detailed with the info when I got it
 

08GT500

Active Member
Jul 12, 2018
460
52
38
Massachusetts
Best pic I have right now. I can get a better one in a couple hours
Hi, only thing I see different cause is the CAI, the placement of the MAF and IAT are different than stock. It will probably have no effect, and again- you will be revert back to the previous Tune, for whatever reason.
You won’t lose your OE tune with an X3, nothing is deleted without at minimum 2 “are you certain you wish to delete this?” warnings.
Your 2001 Mustang GT’s stock injectors should be Yellow in color, 19 lbs. Even if larger, it’s the MAF that needs to be calibrated for the injectors, not the CPU.
I cant see if you have Headers, Long Tube headers require a tune due to 02 sensor location. Shortys are run without a tune, are better with a tune, but will run fine without.
Accel Coils have no affect, and the vacuum system routing looks stock. If it has no internal mod’s, L.Tube headers, it should have no problems running the stock tune. Bringing me to another question...
Why wouldn’t you diagnose the issue as is, running the Tune it has?
Don’t use the Tuner, use a Scantool you can borrow from a friend, or go to Autozone & borrow theirs. You want to see what the fuel pressure is, as reported by the CPU. Get a Scantool that allow you to watch streaming parameters, and run with freeze frame data, so when the code occurs, it holds every parameter, (and where they should be as reference) when the problem starts.
I’d be looking for a cracked vacuum line, connectors that may not be seated fully, and any wiring that may be cut, or scraping on the Chassis.
A fuel pressure gauge would be very helpful to mount permanently on the rail. Check your Fuel filter, and go from tank and follow connectors, lines having to do with the fuel system forward. I think changing the tune may complicate things for you.
Would you like help in finding the reason it throws a code, or continue in removing the Tune from the Car.
I strongly suggest troubleshooting the error, then working with the Computer reflash. I can pretty much guarantee they’re unrelated. The X3 is a great Tuner, but it’s scantool limitations are vast.
I’ll help you whatever your decision, get you on track for Tunes with BAMA, if you plan on adding a few basic Bolt-on’s in the future.-k?
Best!
- John
 

Paradox2018

Member
Oct 9, 2019
21
2
13
19
Pennsylvania
Hi, only thing I see different cause is the CAI, the placement of the MAF and IAT are different than stock. It will probably have no effect, and again- you will be revert back to the previous Tune, for whatever reason.
You won’t lose your OE tune with an X3, nothing is deleted without at minimum 2 “are you certain you wish to delete this?” warnings.
Your 2001 Mustang GT’s stock injectors should be Yellow in color, 19 lbs. Even if larger, it’s the MAF that needs to be calibrated for the injectors, not the CPU.
I cant see if you have Headers, Long Tube headers require a tune due to 02 sensor location. Shortys are run without a tune, are better with a tune, but will run fine without.
Accel Coils have no affect, and the vacuum system routing looks stock. If it has no internal mod’s, L.Tube headers, it should have no problems running the stock tune. Bringing me to another question...
Why wouldn’t you diagnose the issue as is, running the Tune it has?
Don’t use the Tuner, use a Scantool you can borrow from a friend, or go to Autozone & borrow theirs. You want to see what the fuel pressure is, as reported by the CPU. Get a Scantool that allow you to watch streaming parameters, and run with freeze frame data, so when the code occurs, it holds every parameter, (and where they should be as reference) when the problem starts.
I’d be looking for a cracked vacuum line, connectors that may not be seated fully, and any wiring that may be cut, or scraping on the Chassis.
A fuel pressure gauge would be very helpful to mount permanently on the rail. Check your Fuel filter, and go from tank and follow connectors, lines having to do with the fuel system forward. I think changing the tune may complicate things for you.
Would you like help in finding the reason it throws a code, or continue in removing the Tune from the Car.
I strongly suggest troubleshooting the error, then working with the Computer reflash. I can pretty much guarantee they’re unrelated. The X3 is a great Tuner, but it’s scantool limitations are vast.
I’ll help you whatever your decision, get you on track for Tunes with BAMA, if you plan on adding a few basic Bolt-on’s in the future.-k?
Best!
- John
Thank you for all the help! I will add some more pictures of the engine in case that will help... I’m not sure about the headers/long tube headers but the previous owner didn’t mention anything so I doubt my car has them.

I’d like some help with figuring out why the code is being thrown. I recently changed the fuel filter because I thought that might fix the issue and that helped the car run better but the code was still coming back.

I’ll check for vacuum leaks tomorrow and I’m also changing the spark plugs tomorrow just as a precaution
 

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08GT500

Active Member
Jul 12, 2018
460
52
38
Massachusetts
Hi, Great Pic’s! It’s helpful to have a fuel pressure gauge on the fuel rail (pic below), use a 1/4”NPT Y filling to install both the valve & gauge, gauges are typically 1/8” NPT, use a 90 degree fitting for the gauge in the 1/4” NPT Y, so the gauge will sit, horizontally.
Motor does appear stock, aside from the CAI & Coils, can’t quite see- but seems like stock exhaust manifolds, assuming OE Cat’s are still in place. Issues like this can range from the fuel pump, a line split inside the tank at the pump, wiring to the pump, connectors under the tank, inertia switch wiring loose, fuel pressure regulator, worst- CCRM, but car primes when key turns, correct? Fans kick on when car’s warm, correct?
Pull the line off the Fuel pressure regulator, see if you taste, or detect very strong odor of fuel, line from regulator in mouth with small suction applied.(Pic showing regulator below). Get a list together later today, 2:45 here, up at 4:30AM. Niters!
- John
 

Paradox2018

Member
Oct 9, 2019
21
2
13
19
Pennsylvania
Hi, Great Pic’s! It’s helpful to have a fuel pressure gauge on the fuel rail (pic below), use a 1/4”NPT Y filling to install both the valve & gauge, gauges are typically 1/8” NPT, use a 90 degree fitting for the gauge in the 1/4” NPT Y, so the gauge will sit, horizontally.
Motor does appear stock, aside from the CAI & Coils, can’t quite see- but seems like stock exhaust manifolds, assuming OE Cat’s are still in place. Issues like this can range from the fuel pump, a line split inside the tank at the pump, wiring to the pump, connectors under the tank, inertia switch wiring loose, fuel pressure regulator, worst- CCRM, but car primes when key turns, correct? Fans kick on when car’s warm, correct?
Pull the line off the Fuel pressure regulator, see if you taste, or detect very strong odor of fuel, line from regulator in mouth with small suction applied.(Pic showing regulator below). Get a list together later today, 2:45 here, up at 4:30AM. Niters!
- John
thanks, I’m about to run to the auto store and get the fuel pressure gauges to monitor that.

Yes the car primes when the key is turned and the fans kick on when it’s warm. The only issue I have is when I start the car it sometimes won’t catch, the rpms drop and it will turn back off. If I crank it again right after it starts no problem.

I will also pull the line and smell/taste for fuel.
 

Paradox2018

Member
Oct 9, 2019
21
2
13
19
Pennsylvania
Hi, Great Pic’s! It’s helpful to have a fuel pressure gauge on the fuel rail (pic below), use a 1/4”NPT Y filling to install both the valve & gauge, gauges are typically 1/8” NPT, use a 90 degree fitting for the gauge in the 1/4” NPT Y, so the gauge will sit, horizontally.
Motor does appear stock, aside from the CAI & Coils, can’t quite see- but seems like stock exhaust manifolds, assuming OE Cat’s are still in place. Issues like this can range from the fuel pump, a line split inside the tank at the pump, wiring to the pump, connectors under the tank, inertia switch wiring loose, fuel pressure regulator, worst- CCRM, but car primes when key turns, correct? Fans kick on when car’s warm, correct?
Pull the line off the Fuel pressure regulator, see if you taste, or detect very strong odor of fuel, line from regulator in mouth with small suction applied.(Pic showing regulator below). Get a list together later today, 2:45 here, up at 4:30AM. Niters!
- John
It’s raining where I live so I haven’t been able to do much yet, but I did a little driving while data logging the fuel rail pressure using the SCT scanner. The fuel pressure while off and when starting it up was around 50psi and idled around that too. When I start to drive it drops to around 45 and then shortly after it remained at a pretty constant 39. Is this low?
 

08GT500

Active Member
Jul 12, 2018
460
52
38
Massachusetts
Hi,
Can do the rest on a better day. Answer to your question- No, pressure is not too low at 39 PSI. It’s actually pretty optimal. It’s the higher side that is unusual, 50 psi. It’s within range, just a bit excessive jumping to that without slamming the GO pedal to the floor at escalating rpm’s so the pressure keeps up behind the fuel volume being used.
@ Idle, range is between 30-50 calculating various scenario’s.
Since you have a returnless system, the pump controls the fuel pressure to maintain pressure >30lbs while running through hard acceleration. You have an FPRS on the front of your drivers side fuel rail, this is to communicate actual fuel pressure in the loop It has a vacuum line & plug attached to it.
Check the connections for both.
I’m interested in what your pump’s PRIME pressure is, the fuel system pressurizing the lines on a cold start.
That will be great information. This issue started occurring suddenly, correct? Wasn’t like this when purchased?
Acceleration have any flat spots, or interruptions while driving normally, or hard?
Best!
- John
 

Paradox2018

Member
Oct 9, 2019
21
2
13
19
Pennsylvania
Hi,
Can do the rest on a better day. Answer to your question- No, pressure is not too low at 39 PSI. It’s actually pretty optimal. It’s the higher side that is unusual, 50 psi. It’s within range, just a bit excessive jumping to that without slamming the GO pedal to the floor at escalating rpm’s so the pressure keeps up behind the fuel volume being used.
@ Idle, range is between 30-50 calculating various scenario’s.
Since you have a returnless system, the pump controls the fuel pressure to maintain pressure >30lbs while running through hard acceleration. You have an FPRS on the front of your drivers side fuel rail, this is to communicate actual fuel pressure in the loop It has a vacuum line & plug attached to it.
Check the connections for both.
I’m interested in what your pump’s PRIME pressure is, the fuel system pressurizing the lines on a cold start.
That will be great information. This issue started occurring suddenly, correct? Wasn’t like this when purchased?
Acceleration have any flat spots, or interruptions while driving normally, or hard?
Best!
- John
Sorry for the gap in my reply’s, I’ve been super busy over the last few days and working on the car in my free moments.

I used all the information you helped with to narrow my problem down to a few things, I changed the spark plugs and the car has been running great after that so far. I haven’t been able to drive a lot though.

I think the spark plugs were the issue, as they were never changed by the previous owner. Whenever I drive more later today I’ll reply again letting you know if the problem is still happening or not.

Thanks again for all the help so far, I really appreciate it!
 
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