Rough idle with auto start/stop disabled and A/C on

[rcadd1ct]

Watching it I think it is the auto stop start logic circuit.

It is about to shut off and then sees the switch to bypass the start stop and it does a little bobble.

 

[flea_sly]

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[REMIX]

Old thread but currently at 1,700 miles I have this rough idle thing occasionally. It likes to hesitate a bit on acceleration after a cold start @ around 1/2 throttle, too, almost like if I completely took my foot off the gas. Kind of startled me today because it lurched pretty hard. Smooth as butter after that happened. What gives?

 

[MAMiller44]

Reviving this old thread, anyone ever find a solution?

I have a 2019 w/ 13k miles and have this, bringing it into the dealership on Monday. Mods include AFE CAI, Boomba BOV adapter, and Cobb Stage 1 93 tune. Mine ONLY occurs with A/C on. I can have cooled seats on and the air on full blast if it's venting, but the moment you click to actually turn the A/C on it'll do it. Can't see a noticeable drop in RPM when it happens. I'll plug in the Cobb Accessport this weekend to remove the tune and not freak out the dealership...when I do I'll also drive around a bit to check with the digital readout to see if RPMs change and that's what's causing it.

I'll keep everyone posted with what I find on Monday.

 

[Traffic22]

I have a 2018 with 11k miles now, does same thing, but usually only at the first stop. Once I drive off and stop agin, idle is smooth. I just assumed it was a little load on the engine from the AC.

I recently had the PCM software updated, and it’s not as bad. Notice a little hiccup once in a while, but again, usually only the first time I come to a stop.


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[MAMiller44]

After pulling the Cobb tune off, it still did it but after the truck warmed up for 10+ minutes it definitely wasn't as bad. With or without the tune I didn't catch any noticeable drop in RPMs when the compressor kicks on. The dealer pretty much checked everything that would normally cause a rough idle and everything was copacetic. I got in three different Raptors they had on the lot. One new Shelby 2020, one new stock 2020, and one used 2019...all did the same thing. So my comfort level is there that it's normal and not affecting anything. When I'm done with engine/exhaust modifications and get a custom tune, I'll probably ask to increase the idle RPM just a smidge to get rid of it.

 

[SRPRACING]

It’s quite normal. It’s just the nature of the ecoboost. It gets better with higher quality fuel.

 

[MAMiller44]

It’s quite normal. It’s just the nature of the ecoboost. It gets better with higher quality fuel.

Seeing as I only use top tier 93 I’d be really pissed off on anything less lol

 

[Smokey]

my '19 with 20k on the odometer does the same thing after start up on hot days. it's never happened when the outside temp is below 85*.


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[GCATX]

my '19 with 20k on the odometer does the same thing after start up on hot days. it's never happened when the outside temp is below 85*.


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Same.
I think it happens when the cooling fans kick into high speed. Those things really howl.