2019 Mustang 5.0 idling issues

[uikube]

Having issues with the 5.0, its a 2019 10r80, performance pack 1. where it randomly idles down when at a stop.
Mods, intake, headers, E85R Lund tune

Fixes i have tried so far:
Checked with Lund, Not a tune issue.
No Vac Leaks that i can find (triple and quadruple checked)
Replaced VVT Solenoid on driver side (read that this one could go bad so i replaced it just in case)
E85 is always testing good.
NO CODES
Mass air flow sensor looks good, hard to diagnose if it could be this or not outside of replacing it (did CAREFULLY spray it out with MAF spray)
Put 5w-30 oil in just in case ( i read FBO set ups need thicker oil)

I am at a loss. and on the border of selling it. any suggestions would help, thank you!

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[joe603]

I'd have another tuner take a stab at it. Wengerd is fantastic and can probably offer a free tune (with a speed limiter) to see if it makes the issue go away.

 

[DougS550]

Having issues with the 5.0, its a 2019 10r80, performance pack 1. where it randomly idles down when at a stop.
Mods, intake, headers, E85R Lund tune

Fixes i have tried so far:
Checked with Lund, Not a tune issue.
No Vac Leaks that i can find (triple and quadruple checked)
Replaced VVT Solenoid on driver side (read that this one could go bad so i replaced it just in case)
E85 is always testing good.
NO CODES
Mass air flow sensor looks good, hard to diagnose if it could be this or not outside of replacing it (did CAREFULLY spray it out with MAF spray)
Put 5w-30 oil in just in case ( i read FBO set ups need thicker oil)

I am at a loss. and on the border of selling it. any suggestions would help, thank you!

Mine does that. Whipple stage 2 3.5 pulley on E85. Wengerd said he will address that issue once my final data log is complete.

 

[NGOT8R]

@uikube do you have a video of rhe erratic idle, so we can hear it?

My 2019 with Headers, x-pipe, axle back, PMAS (tuned by Lund for E85 also), has done a couple of weird things regarding idle. At first the idle would hang for 10-15 seconds when coming to a stop in neutral. This issue worked itself out with lots of driving. However, recently, the idle has been fluctuating (drops down about 200 rpm and returns to normal idle). I only notice this when the cylinder head temp reaches 210+.

 

[uikube]

@uikube do you have a video of rhe erratic idle, so we can hear it?

My 2019 with Headers, x-pipe, axle back, PMAS (tuned by Lund for E85 also), has done a couple of weird things regarding idle. At first the idle would hang for 10-15 seconds when coming to a stop in neutral. This issue worked itself out with lots of driving. However, recently, the idle has been fluctuating (drops down about 200 rpm and returns to normal idle). I only notice this when the cylinder head temp reaches 210+.

i can get a video for you. but the issue is the same for me, i will come to a stop at a light and the car will shudder and idle down form 750 ish rpms down to 500 and back us, repeatadly.

 

[ORRadtech]

This may, or may not be useful. But if someone with a stock car told me those symptoms one of the first things I'd think is a failing evap purge valve. They can sometimes cause that dip in idle without throwing a code.
Don't know how it affects a supercharged/ tuned car so if it's not applicable or helpful feel free to ignore.

 

[uikube]

This may, or may not be useful. But if someone with a stock car told me those symptoms one of the first things I'd think is a failing evap purge valve. They can sometimes cause that dip in idle without throwing a code.
Don't know how it affects a supercharged/ tuned car so if it's not applicable or helpful feel free to ignore.

to clarify, this is what you're talking about?

 

[NGOT8R]

i can get a video for you. but the issue is the same for me, i will come to a stop at a light and the car will shudder and idle down form 750 ish rpms down to 500 and back us, repeatadly.

What are your cylinder head temps when the idle fluctuation occurs? Mine doesn’t do it all of the time, only when the temps get north of 200*. I wonder if it’s an issue with the cam phasers and solenoids? I saw a video a couple of years ago where Alex Flores’ car did it. Take a look here. The first stumble occurs at 7:05 into the video, but please watch the entire video for more info.

 

[ORRadtech]

to clarify, this is what you're talking about?

Yes, that's the one. If that's what the 5.0 uses it's a simple swap. My wife's Fusion's one looks like an octopus with all it's tubing.

 

[uikube]

Yes, that's the one. If that's what the 5.0 uses it's a simple swap. My wife's Fusion's one looks like an octopus with all it's tubing.

i'll take a look into it, thank you!

 

[ORRadtech]

i'll take a look into it, thank you!

You're welcome, I hope it helps. It may not, idk.
But I've had 3 Fords with the idle drop symptom and that fixed it. 3 different engines (no v8s) and only one threw a code.

 

[uikube]

This may, or may not be useful. But if someone with a stock car told me those symptoms one of the first things I'd think is a failing evap purge valve. They can sometimes cause that dip in idle without throwing a code.
Don't know how it affects a supercharged/ tuned car so if it's not applicable or helpful feel free to ignore.

I checked this today after I saw your comment. and unfortunately no issues with it. Did some tests I found online and everything checks out

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