Car Stalling or "Stuttering" when Idle

[dboutote]

Hi,

I drive a 2017 Fiesta ST. It has 5K miles (and change) on it. Custom e-tuned by Jason @ Dizzy.
Mods:

• COBB FMIC and Piping Kit
• COBB High Flow Air Filter
• COBB RMM
• Whoosh Hybrid Turbo
• Whoosh Catless Downpipe
• Flowmaster American Thunder Catback Exhaust
• Mountune Sound Symposer Delete
• Mountune High Flow Induction Hose
• NGK Step Colder Plugs (gapped .023)
• Turbosmart Dual Port Shortie BOV

I haven't had the car for very long (as you can probably tell by mileage). I live in Florida so it takes some heat. The car tends to drop below 600 or 500 RPM and "stutter" or seem like it's about to stall when in idle and then jump back up to it's desired RPM (800-850 range). The car stalled for the first time when I came to a complete stop and pushed the clutch pedal in while in Neutral. It drives fine other than that. I've looked up almost everything from the CPV/fuel feed, bad spark plugs, fuel pressure sensor, etc...

Kinda not sure if taking it to Ford at this point is an option. Really don't want them to blame the bigger turbo or tune or anything like that. All I know is that it's obnoxious and I really would like to get rid of it.

 

[TyphoonFiST]

Spark plugs might be gapped too tight....

 

[PunkST]

Have you been over filling the fuel tank when you get fuel? There have been repeat issues across the range of cars with the evap system due to overfilling the tank.

Another thing to check is vacuum leaks. They can do some odd stuff. On my old car i had a line tear and for 6 months it idled like it had a big set of cams, lol.

 

[LastMK7]

Recheck your BOV. If it has moved at all from its factory setting then it could be causing idle issues.

 

[Sam4]

I tried the one-step colder approach (93 tune w/Livernois), and did not like the way the car ran. Back to factory temp and everything is copacetic.

 

[dboutote]

I tried the one-step colder approach (93 tune w/Livernois), and did not like the way the car ran. Back to factory temp and everything is copacetic.

that's interesting, I'll try this

 

[SlowDunny]

• NGK Step Colder Plugs (gapped .023)

That is a tight spark gap, loosen that bad boy up to 0.026

 

[flat_lander]

Dizzy tuning recommends .028 on their website. Agreed, they need opened up.

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[TyphoonFiST]

Spark plugs might be gapped too tight....

Must be a huge cave....in here

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[dboutote]

Here's a video of what happens... I rev a little bit and this

http://imgur.com/rnFmiou

View: https://imgur.com/rnFmiou

 

[green_henry]

112 F? If the car thinks it's that hot, maybe it's just trying to save itself from melting

 

[TyphoonFiST]

Here's a video of what happens... I rev a little bit and this

http://imgur.com/rnFmiou

View: https://imgur.com/rnFmiou

Does it do it only with the A/c ? Or does it do it regardless?

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[TyphoonFiST]

Do you have a tune or is it stock? If its tuned have the Tuner set the idle higher see if that helps.

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[dboutote]

112 F? If the car thinks it's that hot, maybe it's just trying to save itself from melting

Haha, I live in FL. I don't know if I have a thermostat issue either

 

[dboutote]

Do you have a tune or is it stock? If its tuned have the Tuner set the idle higher see if that helps.

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He set it to 850. I revert it back to stock tune so I can take it to the dealership on Wednesday. It does it with and without A/C on.

 

[SlowDunny]

Judging by the fact you have a full tank it, I think it is related to the evap/venting for fueling.

I just replaced my evap purge valve hunting down the same issue. On fill ups, even after leaving the filler in for 15-20 seconds after filling, I would get this rich AFR spontaneously at idle and the ecu would overcompensate and make it almost stall.

 

[dboutote]

Hey guys,

Car does it even when it's 52mi to E / all the time.
I have replaced the Lowside Fuel Pressure Sensor (an issue I read about in the EcoBoost Mustangs), Fuel Rail Pressure Sensor up at the fuel rail, Throttle Body assembly (was wondering if throttle position sensor was glitching), MAF replaced and I've even gone back to stock tune and it still does it. Spark plugs are gapped at .026.

Thinking it is a bad MAP sensor. Any ideas?

 

[dboutote]

Did a smoke test and there is no vacuum leak. Did a compression test and got 185/195/200/200. All in good condition there.

What could this be!?

 

[Intuit]

Car is brand-spanking new. Bad this and that is unlikely. Due to changes, some things are out of parameter, for which the ECU needs to be reprogrammed for. (by qualified personnel who actually know what they're doing)

 

[Ford ST]

Well you really shouldn't ever run it on the stock tune with an upgraded Turbo.
With all these upgrades that have been done at what point did you start having issues?

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