2014 Idle Hunting High Fuel Trim

[ito717]

Sitting at a stoplight and all of a sudden my stock 2014 GT Track Pack started bouncing around between 600 and 750 rpm at idle. I pulled up gauges and noted the air/fuel ratio moving, managed to catch a video at the next stoplight:

Hooked up a cheap code reader and noticed long fuel trims seemed high: LONGFT1: ~12.5 and LONGFT2: 7 Recorded a video of these too:

I have removed and cleaned the MAF and Throttle Body and removed the negative battery cable for ~10mins to reset the ECU and relearn idle. Problem still persists.

I'm thinking maybe a vacuum leak, but not really sure where to start?

Thanks in advance,

Ito

 

[SilBult]

If you think it might be a vacuum leak and you have an oil catch can I would check the the fittings and the can itself. Good luck.

 

[ito717]

No oil catch can installed here.

 

[Edqe]

Fuel pump. PCM telling pump to work harder to maintain demand.

 

[ito717]

Fuel pump. PCM telling pump to work harder to maintain demand.

Thanks for the tip. Is there any data from the fuel pump in Forscan that I can see to further validate its the fuel pump?
Smoke tested the whole vacuum system yesterday and didn't find anything out of the ordinary, so my original theory was wrong.

 

[Edqe]

Thanks for the tip. Is there any data from the fuel pump in Forscan that I can see to further validate its the fuel pump?
Smoke tested the whole vacuum system yesterday and didn't find anything out of the ordinary, so my original theory was wrong.

I use BlueDriver scan tool. Gives fuel pressure readings. Not sure about forescan. If you do find it. Fuel pressure should read near 40psi at idle and cruising speeds. Will drop in the low 30’s at WOT and spike up when you let off the trottle. Anything out of the ordinary, start looking at your fuel pump and injectors.

 

[BruceH]

Sitting at a stoplight and all of a sudden my stock 2014 GT Track Pack started bouncing around between 600 and 750 rpm at idle. I pulled up gauges and noted the air/fuel ratio moving, managed to catch a video at the next stoplight:

Hooked up a cheap code reader and noticed long fuel trims seemed high: LONGFT1: ~12.5 and LONGFT2: 7 Recorded a video of these too:

I have removed and cleaned the MAF and Throttle Body and removed the negative battery cable for ~10mins to reset the ECU and relearn idle. Problem still persists.

I'm thinking maybe a vacuum leak, but not really sure where to start?

Thanks in advance,

Ito

Air that hasn't been metered is where I would start. Vacuum leak or something with the air intake. An aftermarket cai could be the culprit as could a dirty maf which would replicate unmetered air to the computer.

You already cleaned the maf and basically have covered all the bases. Maybe it's the pcv?

 

[JMAAS]

Sitting at a stoplight and all of a sudden my stock 2014 GT Track Pack started bouncing around between 600 and 750 rpm at idle. I pulled up gauges and noted the air/fuel ratio moving, managed to catch a video at the next stoplight:

Hooked up a cheap code reader and noticed long fuel trims seemed high: LONGFT1: ~12.5 and LONGFT2: 7 Recorded a video of these too:

I have removed and cleaned the MAF and Throttle Body and removed the negative battery cable for ~10mins to reset the ECU and relearn idle. Problem still persists.

I'm thinking maybe a vacuum leak, but not really sure where to start?

Thanks in advance,

Ito

Hey man did u ever get this fixed having a similar issue but much higher ltft(27+ both banks) and also no sign of leak from smoke test

 

[Juice]

Ito, those trims aren't too bad. About the same as mine. Likely not the issue.
JMAAS, do you have cats?

 

[UpAllNight91]

Positive fuel trims. If it was a fuel pump I would expect to see positive trim more under heavy load than only just at idle. If heavy load trims look good then I would say the pump is fine. Sometimes Positive trims can be caused by misfires and incomplete combustion. As this does send oxygen down the exhaust pipe and the computer sees this as a lean condition, so it adds fuel. Also don't rule out o2 sensors. If they are old it wouldn't hurt swapping them out. And if you do I would replace both front and rear because the rear is used on these cars to keep the front calibrated so the rears are just as important as the front upstream on these cars

 

[delroy]

I have only a basic knowledge but we recently had a similar issue on our Ford Edge with the 3.5L V6.
The purge valve or "solenoid valve" is part of the evap system. The purge valves are notorious for this type of problem. A bad purge valve can affect fuel trims etc. Luckily, they are not expensive and are usually pretty easy to change. Their default position is closed. Just a simple spring and a solenoid. They often plug in directly to the intake manifold. (Not sure about a Mustang.) Investigate this for your engine. It's a bit of a parts cannon approach, but may be reasonable in your case.