Sponsored

MAF / Stalling question (HELP)

Voo Doo

Well-Known Member
Joined
Apr 18, 2015
Threads
128
Messages
2,587
Reaction score
1,863
Location
Surrey BC
First Name
Ric
Vehicle(s)
2019 BULLITT DHG
Well this sounds like the issue I am having. IDK if turbulence is the factor though. Yes it has dies before while still coming to a stop, but I have also came to a complete stop and then for no reason it starts to stumble 10 seconds after stopping and then will at times even act like its missing a few cylinders when I go to take off. I do have a JLT 110 CIA with tune on it, however it just started doing it about 6 months ago and the tune has been on for a couple years. Thought it was bad gas so switched stations a couple time with no change. Very intermittent too, I may go days or a week and its fine then all of a sudden its acting like a turd.
So....do you downshift or simply push the clutch in and coast to the stops??? You have turbulence somewhere!! Too much air!! Try down shifting if you don’t already do it!!...or just leave it in gear til you stop!!
Sponsored

 

Zelek

Well-Known Member
Joined
Feb 11, 2016
Threads
102
Messages
4,818
Reaction score
4,772
Location
Hutto, TX
First Name
Matt
Vehicle(s)
2021 Mustang Mach 1
So....do you downshift or simply push the clutch in and coast to the stops??? You have turbulence somewhere!! Too much air!! Try down shifting if you don’t already do it!!...or just leave it in gear til you stop!!
Unfortunately, that's not always an option sometimes when you catch a stop light wrong or unexpected traffic. A lot of the times I downshift and just engine brake as long as there's plenty of room. My car died twice on me last week leaving work just going home with a 2018 JLT intake and tune. RPM dips to about 500, Lamba goes to about .76 to .78 then it dies. Sometimes I'd be able to recover from it and give it a little gas to keep it from dying. It's a very intermittent problem though.
 
OP
OP
Meat coyote racing

Meat coyote racing

Well-Known Member
Joined
Sep 4, 2018
Threads
17
Messages
98
Reaction score
35
Location
28376
First Name
Zack
Vehicle(s)
2017 GT PP
Well this sounds like the issue I am having. IDK if turbulence is the factor though. Yes it has dies before while still coming to a stop, but I have also came to a complete stop and then for no reason it starts to stumble 10 seconds after stopping and then will at times even act like its missing a few cylinders when I go to take off. I do have a JLT 110 CIA with tune on it, however it just started doing it about 6 months ago and the tune has been on for a couple years. Thought it was bad gas so switched stations a couple time with no change. Very intermittent too, I may go days or a week and its fine then all of a sudden its acting like a turd.
Well, for what it's worth, it has been 7 months since I adjusted the air filter (moving it away from the big mouth) and I haven't had a stall since. I am still convinced it was turbulent air.
 

Zelek

Well-Known Member
Joined
Feb 11, 2016
Threads
102
Messages
4,818
Reaction score
4,772
Location
Hutto, TX
First Name
Matt
Vehicle(s)
2021 Mustang Mach 1
Well, for what it's worth, it has been 7 months since I adjusted the air filter (moving it away from the big mouth) and I haven't had a stall since. I am still convinced it was turbulent air.
Think the Velossatech is causing the extra turbulence? The times mine died were at pretty low speeds, but possibly enough to funnel some extra air through the filter.
 
OP
OP
Meat coyote racing

Meat coyote racing

Well-Known Member
Joined
Sep 4, 2018
Threads
17
Messages
98
Reaction score
35
Location
28376
First Name
Zack
Vehicle(s)
2017 GT PP
Think the Velossatech is causing the extra turbulence? The times mine died were at pretty low speeds, but possibly enough to funnel some extra air through the filter.
I think the Velossatech was a contributing factor. It was probably the big mouth, MMD V series grille, and PMAS air filter placement. They all equated to too much air blowing on the filter which was causing stall issues coasting, in neutral. The car would never stall in gear and in 20.00 vacuum
 

Sponsored

natepcbfl

Well-Known Member
Joined
Jul 20, 2016
Threads
7
Messages
422
Reaction score
203
Location
New Hope, AL
First Name
Nathan
Vehicle(s)
2015 Mustang Premium GTpp 50th AP ---- 1989 Mustang GT 25th Anniversary
Vehicle Showcase
2
So....do you downshift or simply push the clutch in and coast to the stops??? You have turbulence somewhere!! Too much air!! Try down shifting if you don’t already do it!!...or just leave it in gear til you stop!!
I usually only downshift when I am going to go around a corner, otherwise I just push in the clutch and put in N when coming to a stop light or stop sign. I dont think turbulence is the issue since I can't recreate it, even if I take the exact same path at the same speed and everything. If it was a turbulence issue it should have been happning right after the JLT was installed, yet like I said it was on for a year and a half before this issue arose out of the blue. The only thing consistent with it is, it happens after driving for a bit.
 

natepcbfl

Well-Known Member
Joined
Jul 20, 2016
Threads
7
Messages
422
Reaction score
203
Location
New Hope, AL
First Name
Nathan
Vehicle(s)
2015 Mustang Premium GTpp 50th AP ---- 1989 Mustang GT 25th Anniversary
Vehicle Showcase
2
Update for this morning. I got off the highway this morning, merged into traffic doing about 30, came to a stop at the light. Car was fine for about 10 seconds then it started it shit. RPMs dropping, tapped the gas and it straightened out went to take off about 20 seconds later and the car was spitting and sputtering. After driving about 10 seconds it was ok. Got up to 45mph, pulled into the bank to make a deposit. pulled into the parking lot, pulled up to the ATM and after about 20 seconds it started again. Went to leave and again its running like shit but went away after i got to about 30mph. Got to work never got above 45mph. Pulled in the parking lot and broke out the video and started recording, pulled into my parking spot, put into N, pulled the parking brake and was still recording for about 45 seconds and no issue. Of course just after I shut off the video it started up again. Pedal tap and it stopped. This weekend I will be replacing the stock plugs and cleaning the CIA filter and MAF. No fuel filter to clean from what I have gathered :(. Turbulence has definitely been ruled out, at least for my issue.

2015 GTpp w/50AP - 96k on the clock
 

natepcbfl

Well-Known Member
Joined
Jul 20, 2016
Threads
7
Messages
422
Reaction score
203
Location
New Hope, AL
First Name
Nathan
Vehicle(s)
2015 Mustang Premium GTpp 50th AP ---- 1989 Mustang GT 25th Anniversary
Vehicle Showcase
2
Monday update.
Changed the plugs Sunday and although it didnt spit and sputter when I was trying to take off at any point this morning it did stumble once at a red light just for a second and then also when I parked ( 40 seconds into the video). It only stumbled once and just briefly in the video, usually it acts up for a duration of at least 3 to 5 seconds. MAF will be cleaned tonight, retest. CAI will be cleaned next, retest. Had a buddy mention O2s anybody had the O2s make this issue happen?
 

CrashOverride

Well-Known Member
Joined
Aug 18, 2018
Threads
45
Messages
680
Reaction score
376
Location
Under a hood
Vehicle(s)
2015 Mustang GT
Without a log I can't tell, but I think your voltage is too low. 12.7v seems low. When it almost stalls, it falls to what looks like 12.2v.

Is that your original battery?

Fuel injector drivers need the voltage to be very stable, there is only so much offset to compensate for lower voltage. Other sensors get screwy at lower voltages as well. I haven't paid attention to what my car reads voltage wise, but typical charging voltage is above 13v.

If you are going to clean your MAF, only use MAF cleaner.

I'd buy a OBDLink-MX and connect it to your computer or phone, and log a few different parameters including the MAF period. It will not only help you with this issue, but future issues, or for ForScan, or even for future cars. I consider it just as needed as a ratchet nowadays.
 

natepcbfl

Well-Known Member
Joined
Jul 20, 2016
Threads
7
Messages
422
Reaction score
203
Location
New Hope, AL
First Name
Nathan
Vehicle(s)
2015 Mustang Premium GTpp 50th AP ---- 1989 Mustang GT 25th Anniversary
Vehicle Showcase
2
Without a log I can't tell, but I think your voltage is too low. 12.7v seems low. When it almost stalls, it falls to what looks like 12.2v.

Is that your original battery?

Fuel injector drivers need the voltage to be very stable, there is only so much offset to compensate for lower voltage. Other sensors get screwy at lower voltages as well. I haven't paid attention to what my car reads voltage wise, but typical charging voltage is above 13v.

If you are going to clean your MAF, only use MAF cleaner.

I'd buy a OBDLink-MX and connect it to your computer or phone, and log a few different parameters including the MAF period. It will not only help you with this issue, but future issues, or for ForScan, or even for future cars. I consider it just as needed as a ratchet nowadays.
Just got a new battery almost 2 weeks ago. IDK what the voltage is supposed to be while idling. I know its fine while driving, as you can see pulling into the parking t it was at 13.9. If the low voltage is the culprit then it should do it all the time when the voltage is low, right? Even after the stumble I'm sitting there with 12.7v and no issues for the remainder of the video. I will have to see about logging things , but IDK how to tell what the logs would say. Maybe Ill be able to post it up here and someone might know what is the issue.
 

Sponsored

CrashOverride

Well-Known Member
Joined
Aug 18, 2018
Threads
45
Messages
680
Reaction score
376
Location
Under a hood
Vehicle(s)
2015 Mustang GT
Just got a new battery almost 2 weeks ago. IDK what the voltage is supposed to be while idling. I know its fine while driving, as you can see pulling into the parking t it was at 13.9. If the low voltage is the culprit then it should do it all the time when the voltage is low, right? Even after the stumble I'm sitting there with 12.7v and no issues for the remainder of the video. I will have to see about logging things , but IDK how to tell what the logs would say. Maybe Ill be able to post it up here and someone might know what is the issue.
It's hard to say if the voltage caused the stumble or if the stumble caused the voltage drop. I think you're okay at 12.7v, but 12.2 is fairly low.

I think the problem is the MAF though. If you did a mail order tune, I would reach out to them and see if they would be willing to tweak your tune to utilize the stock MAF. The PMAS one is different, and I doubt that the tuners know the properties as well as the stock one. If the calibration isn't correct, then it's going to run poor. At idle, the airflow across the sensor is quite low, so it is especially vulnerable to hunting idle and so forth at idle.

The nice thing about the stock MAF is that the values are known for it. If you throw in a bigger MAF chamber (Larger diameter intake) then the flow will go down --but-- you can tweak the tables fairly easy by reducing the airflow period by the percentage of change. Arguably, it is much easier to tweak a sensor with known values/curves than to tweak an unknown sensor.
 

natepcbfl

Well-Known Member
Joined
Jul 20, 2016
Threads
7
Messages
422
Reaction score
203
Location
New Hope, AL
First Name
Nathan
Vehicle(s)
2015 Mustang Premium GTpp 50th AP ---- 1989 Mustang GT 25th Anniversary
Vehicle Showcase
2
It's hard to say if the voltage caused the stumble or if the stumble caused the voltage drop. I think you're okay at 12.7v, but 12.2 is fairly low.

I think the problem is the MAF though. If you did a mail order tune, I would reach out to them and see if they would be willing to tweak your tune to utilize the stock MAF. The PMAS one is different, and I doubt that the tuners know the properties as well as the stock one. If the calibration isn't correct, then it's going to run poor. At idle, the airflow across the sensor is quite low, so it is especially vulnerable to hunting idle and so forth at idle.

The nice thing about the stock MAF is that the values are known for it. If you throw in a bigger MAF chamber (Larger diameter intake) then the flow will go down --but-- you can tweak the tables fairly easy by reducing the airflow period by the percentage of change. Arguably, it is much easier to tweak a sensor with known values/curves than to tweak an unknown sensor.
Ill be cleaning the MAF tonight and testing, then the filter this weekend. I have an SCTx4 that I used the canned tune supplied for a JLT 110mm CAI. Its been fine for quite some time so I am leery on thinking the tune is the issue. I did have a friend tell me he was having a similar issue and it ended up being a O2 sensor.
 

natepcbfl

Well-Known Member
Joined
Jul 20, 2016
Threads
7
Messages
422
Reaction score
203
Location
New Hope, AL
First Name
Nathan
Vehicle(s)
2015 Mustang Premium GTpp 50th AP ---- 1989 Mustang GT 25th Anniversary
Vehicle Showcase
2

natepcbfl

Well-Known Member
Joined
Jul 20, 2016
Threads
7
Messages
422
Reaction score
203
Location
New Hope, AL
First Name
Nathan
Vehicle(s)
2015 Mustang Premium GTpp 50th AP ---- 1989 Mustang GT 25th Anniversary
Vehicle Showcase
2
UPDATE: I changed the plugs - no success ... cleaned the MAF and filter - no success ... going to throw the stock airbox and tune on tonight and see if it still is an issue. If it still does it then I guess I will have to visit the stealership and ask about this TSB ... TSB 15-0128 - https://ford.oemdtc.com/1263/idle-dip-or-loss-of-rpm-with-clutch-pedal-depressed-2015-ford-mustang This is a seriously aggravating issue.
Installed four VCT solenoids Saturday and the idle is rock solid. I honestly dont remember the last time the idle sat so still, it has always wiggled on the gauge a little.
IMG_0240.webp
Sponsored

 
 








Top