My Jeep now hates the summer time

kmart017 · Aug 19, 2021

Hi all! It’s been a while since I posted.

So when the weather started to warm up earlier this year, there were a couple days where it got pretty hot. On those days my idle would sit about 900 - 1000 rpms. As the summer continues and there were more warm days, this happened more often so I started paying more attention. If the temperature outside is 85 degrees and up, it sits at a high idle. 84 degrees and lower, it sits normal at about 700. In really hot weather (100 and up) the tachometer fluctuates at the higher end.

There are no codes, short term fuel trim is higher, no noticeable performance issues, there is a hissing sound from the front left which can only be heard from inside the cabin, the air conditioner has no impact on the rpms, and it is the same in drive and in neutral eliminating possible transmission issues. I threw $20 at it and replaced the MAP sensor but that did nothing.

My current theories are the air intake manifold, vacuum line, throttle body (I replaced the throttle body at 80k I think), or the brake booster (highly doubt it but it sits right in front of the driver). I’m pretty confident it’s an air/vacuum problem. Any ideas? Also,the Jeep is a 2015, 2.4, 4x4, with 140k miles on it.

Thanks in advance!

mr_et2 · Aug 19, 2021

First thing I'd do is change the spark plugs if they've been in there for near 30k miles.

kmart017 · Aug 20, 2021

mr_et2 said:
First thing I'd do is change the spark plugs if they've been in there for near 30k miles.

I changed the spark plugs a few months ago, properly gapped, etc. But bringing that up, Ill check the condition of the coil packs/seals which haven’t been changed since I got the vehicle.

Mikeandrews27 · Feb 10, 2022

kmart017 said:
Hi all! It’s been a while since I posted.

So when the weather started to warm up earlier this year, there were a couple days where it got pretty hot. On those days my idle would sit about 900 - 1000 rpms. As the summer continues and there were more warm days, this happened more often so I started paying more attention. If the temperature outside is 85 degrees and up, it sits at a high idle. 84 degrees and lower, it sits normal at about 700. In really hot weather (100 and up) the tachometer fluctuates at the higher end.

There are no codes, short term fuel trim is higher, no noticeable performance issues, there is a hissing sound from the front left which can only be heard from inside the cabin, the air conditioner has no impact on the rpms, and it is the same in drive and in neutral eliminating possible transmission issues. I threw $20 at it and replaced the MAP sensor but that did nothing.

My current theories are the air intake manifold, vacuum line, throttle body (I replaced the throttle body at 80k I think), or the brake booster (highly doubt it but it sits right in front of the driver). I’m pretty confident it’s an air/vacuum problem. Any ideas? Also,the Jeep is a 2015, 2.4, 4x4, with 140k miles on it.

Thanks in advance!

Finally someone with the same weird problem as me!! Not kidding man, I literally just joined this forum to reply to you. I have literally the same EXACT issue going on that I can’t figure out. Just like your Jeep, mine will start idling around 900/1000 as soon as the temperature hits 85 degrees. When it drops to 84, the idle returns down to normal. I wasted a month last summer trying to solve it and could never figure it out. Even the mechanics I asked had no clue. No codes or anything. Just a high idle when the outside temperature hits 85. Did you ever figure out what was causing your issue?

Ignatz · Feb 11, 2022

Just my 2c worth but I wonder if it's programed that way to keep the coolant circulating a little faster when it's exceptionally hot outside?

Mikeandrews27 · Feb 11, 2022

Ignatz said:
Just my 2c worth but I wonder if it's programed that way to keep the coolant circulating a little faster when it's exceptionally hot outside?

I doubt it because you would here more people talking about it if they all did it. I noticed mine after getting gas last summer. It’s very noticeable because when it’s idling at 900 the steering wheel gets a very annoying vibration chatter and the Jeep noticeably lurch’s forward faster when letting of the break from a stop. It almost seems like it’s getting too much gas. Like it your slightly pushing down on the gas pedal to raise the rpm’s.

mr_et2 · Feb 11, 2022

Sounds like what my FD2 does when I shift into L. Raises the RPMs

DeepCherry2015 · Feb 11, 2022

My 2015 2.4L 4X4 High Altitude also does that. I noticed it most this past summer, as of 6/1/21 traded my car and wife got the new '21 Durango and I got the Patriot as my daily driver. Tend to agree with Ignatz on this. After observing it happen a multitude of times, and seeing and getting no ODBII codes when I scanned it, it absolutely must have something to do with being programmed to behave that way. Additional RPMs for faster coolant circulation? Maybe.
Maybe adding a little more air as it changes mixture due to temps? Maybe.

My plugs are also relatively newer, and this behavior only occurs in extreme hot temps. If plugs were worn/bad, you would get the typical ROUGH idle and hesitation on acceleration on these. For whatever reason have to think it is intentional behavior programmed in. I know running A/C on most models often "bumps" up the idle, but usually no more than 50 - 100 RPMs over normal, so must be something else, as it doesn't always do it when A/C is on.

Mikeandrews27 · Feb 13, 2022

DeepCherry2015 said:
My 2015 2.4L 4X4 High Altitude also does that. I noticed it most this past summer, as of 6/1/21 traded my car and wife got the new '21 Durango and I got the Patriot as my daily driver. Tend to agree with Ignatz on this. After observing it happen a multitude of times, and seeing and getting no ODBII codes when I scanned it, it absolutely must have something to do with being programmed to behave that way. Additional RPMs for faster coolant circulation? Maybe.
Maybe adding a little more air as it changes mixture due to temps? Maybe.

My plugs are also relatively newer, and this behavior only occurs in extreme hot temps. If plugs were worn/bad, you would get the typical ROUGH idle and hesitation on acceleration on these. For whatever reason have to think it is intentional behavior programmed in. I know running A/C on most models often "bumps" up the idle, but usually no more than 50 - 100 RPMs over normal, so must be something else, as it doesn't always do it when A/C is on.

I think it’s odd that it happened to us after recent spark plug change. Did you change the plugs yourself? I did them myself and did everything exactly how they said to. This problem didn't start until about a month after the plug change so I don’t even see how it could be related. But if the Jeep was programmed this way then how come it didn’t do this from the factory? My Patriot is a 2015 too and it just started doing this last summer. Also it’s a pain to drive because of the vibrations from the steering wheel/horn. I wish it would just throw a code. I really have no clue on what it could be after beating my head against the wall for a week last summer. The fact it only happens at certain temperature is the weirdest part.

factotumer · Feb 13, 2022

Mine has the same high idle issue in the heat when it’s above 85 (30C on the outside temp dash display). It also high idles in the cold below 14 (-10C on the dash display)

It's a 2015 Patriot North 105,000 miles, 2.4, 6 speed, I follow the maintenance chart. Use regular copper OE NGK plugs, synthetic oil, K&N air filter and a Pioneer with a CRUX S00CR-26 for the can-bus. I’m in Ontario and our temperature can be from -40F in the winter to just over 100F in the summer, but most of the year we’re between -10C/14F and 30C/85F - the sweet spot for the idle. Canada is metric so I have outside temp in Celsius on the dash.
When it’s over 30C or under -10C the idle jumps about 200 rpm. Between -10C and 30C it drops to idle quickly after starting. Above 30C or below -10C it never drops the high idle and is rough in drive when stopped no matter how warmed up or cold the engine is. If the temp goes in or out of the -10C – 30C range on a trip the idle speed consistently follows the dash temp reading like it’s part of the ECM programming to high idle out of the sweet spot temp range.
I drove for a couple of years with a recording scanner and it never ever showed any issues. Other than rear bearings, all I have had to do is normal maintenance.
But if anyone has a solution, I’d appreciate it.

DeepCherry2015 · Feb 21, 2022

I have changed the plugs myself. Used OE Champion coppers, at correct gap. Was doing it prior to plug change, and after, so NOT related to plugs. The OE coppers on these, after about 30K miles, show symptoms of misfire or hesitation on acceleration. Gaps open up a crazy amount in just 30K - like from .044 to .055-.060! I've done millions of plug changes on all makes/models of cars from back in the 50s to the present, and have not seen that big of a gap increase. Even using OE coppers in my 5.7 Hemi, all 16 plugs show maybe an increase from .044 to maybe .048-.050 tops.

I think this has to be some kind of programmed behavior based on a combo of outside and engine temps.

factotumer · Dec 19, 2022

I finally have the high idle for summer and extreme winter solved on my Patriot. When it was fully warmed up the temp needle always stayed almost touching the half way mark, never over, no matter the outside temperature. I replaced the thermostats and housing. Sticky thermostats. Would only open part way. Now it shows an 1/8" below the half mark or less in colder weather. Not enough to show an "overheat" in Canadian summer but enough to run to hot in a Canadian winter on a long drive. And cause a high idle. The antifreeze might last 10 years but the thermostats don't. BTY I flushed the system clear with distilled water - no tap chlorine water. I didn't use a chemical flush because the old antifreeze was sediment free. I refilled with Preston 10 year HD truck all compatible OAT, POAT, HOAT & IAT. I didn't mix it with any of the OEM and confusing purple or orange non compatible.

Justindm83 · Sep 14, 2023

kmart017 said:
Hi all! It’s been a while since I posted.

So when the weather started to warm up earlier this year, there were a couple days where it got pretty hot. On those days my idle would sit about 900 - 1000 rpms. As the summer continues and there were more warm days, this happened more often so I started paying more attention. If the temperature outside is 85 degrees and up, it sits at a high idle. 84 degrees and lower, it sits normal at about 700. In really hot weather (100 and up) the tachometer fluctuates at the higher end.

There are no codes, short term fuel trim is higher, no noticeable performance issues, there is a hissing sound from the front left which can only be heard from inside the cabin, the air conditioner has no impact on the rpms, and it is the same in drive and in neutral eliminating possible transmission issues. I threw $20 at it and replaced the MAP sensor but that did nothing.

My current theories are the air intake manifold, vacuum line, throttle body (I replaced the throttle body at 80k I think), or the brake booster (highly doubt it but it sits right in front of the driver). I’m pretty confident it’s an air/vacuum problem. Any ideas? Also,the Jeep is a 2015, 2.4, 4x4, with 140k miles on it.

Thanks in advance!

Has anyone figured it out

Justindm83 · Sep 14, 2023

factotumer said:
Mine has the same high idle issue in the heat when it’s above 85 (30C on the outside temp dash display). It also high idles in the cold below 14 (-10C on the dash display)

It's a 2015 Patriot North 105,000 miles, 2.4, 6 speed, I follow the maintenance chart. Use regular copper OE NGK plugs, synthetic oil, K&N air filter and a Pioneer with a CRUX S00CR-26 for the can-bus. I’m in Ontario and our temperature can be from -40F in the winter to just over 100F in the summer, but most of the year we’re between -10C/14F and 30C/85F - the sweet spot for the idle. Canada is metric so I have outside temp in Celsius on the dash.
When it’s over 30C or under -10C the idle jumps about 200 rpm. Between -10C and 30C it drops to idle quickly after starting. Above 30C or below -10C it never drops the high idle and is rough in drive when stopped no matter how warmed up or cold the engine is. If the temp goes in or out of the -10C – 30C range on a trip the idle speed consistently follows the dash temp reading like it’s part of the ECM programming to high idle out of the sweet spot temp range.
I drove for a couple of years with a recording scanner and it never ever showed any issues. Other than rear bearings, all I have had to do is normal maintenance.
But if anyone has a solution, I’d appreciate it.

Anyone figure it out?

Ignatz · Sep 15, 2023

I'd seen the previous posts and I have no solution, although I don't think it's a problem. Mine idles at about the same speed, though initially a little higher in winter before it drops down to normal. I think that has to do with getting the vehicle up to operating temperature more quickly in winter -- both for emissions control and occupant comfort.

My Jeep now hates the summer time

kmart017

mr_et2

kmart017

Mikeandrews27

Ignatz

Mikeandrews27

mr_et2

DeepCherry2015

Mikeandrews27

factotumer

DeepCherry2015

factotumer

Justindm83

Justindm83

Ignatz

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