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

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Cones169

Member
Joined
Apr 7, 2019
Posts
16
Reaction score
6
Location
Long Island
Does anyone have a issue when the a/c is on and and the auto start/stop is disabled. When i first start truck and am just idling in drive the rpm's jump up and down like it wants to stop like when using the auto stop. It eventually goes away after driving for a small bit and then coming to a stop.
 

TxCOR

Active Member
Joined
Sep 8, 2018
Posts
59
Reaction score
62
Location
Florida
I have noticed this too, but its not a big variation in RPMs. I haven't really paid much attention since there hasn't seemed to cause any actual driving issues...

Curious if anyone has dug into this and found it to be something greater than just a cold rough idle.
 

rcadd1ct

Member
Joined
Sep 25, 2016
Posts
18
Reaction score
1
Location
earth
I was having this and the dealer cleaned the intake and it helped for about 7k. Now I get it again. Almost at 30k now. I might change plugs soon.
 

quikag

Full Access Member
Joined
Jul 20, 2019
Posts
324
Reaction score
318
Location
Dallas
New ‘19 less than 1k miles. It’s hot out here in DFW and when I come to a stop rpms are around 500ish. Then I guess the AC compressor kicks in and rpms jump to 750 or so and if I only have my foot lightly on the brake, it’ll try to move forward a bit which is a bit disconcerting. I push a touch harder on the brake and all is well. The rpms don’t fluctuate after settling at 750rpm.

It’s kind of annoying actually, so now I just push a bit harder on the brake while waiting at a light and ignore it when the rpms jump a bit.
 

91Eunos

Full Access Member
Joined
Oct 18, 2018
Posts
644
Reaction score
904
Location
Hill country, Tejas
I do have that too... was going to take it in to the dealer to have it checked out, but now that you mention it, it’s only been happening since I had the cam phasers replaced under warranty. I assumed it was a loose vacuum fitting or something similar, but may be an “update” to the ECU that changed an idle setting.

I always have the engine shutoff disabled but will try it enabled. Will also try it in Sport mode to see if it goes away.
 

sdspa

Member
Joined
Mar 31, 2019
Posts
20
Reaction score
10
Location
Philly
I have a rough idle. It’s more of a feel than seeing the rpm needle move. And it’s when the AC is on or off, and doesn’t matter if stop-start is on or disabled. So I think it’s different than a change in idle due to the AC compressor. I really hope this isn’t a precursor to the cam phaser problem...
 

docskeet1

Full Access Member
Joined
Sep 11, 2018
Posts
376
Reaction score
245
Location
Athens GA
I have an 18, ESS disabled with Forscan. My idle seems too slow at times on a hot day with the AC on and the truck is cold. Smooths out/goes away when the truck warms up. Pressing on the brake has no effect.
 
Top