Want slightly higher idle

[LJ-MXer]

Jeep runs fine. Idles fairly smooth. Gauges show AC high low side numbers close enough to spec. In Southwest Florida right now the heat index is 100 plus and the humidity hangs around 100%, and I have a hardtop that's uninsulated and hot to the touch.
Question 1: is  how high is too high to set the idle without causing any damage to the engine? I THINK the manual is looking for 750rpms at 14%? Currently with the engine OFF with foot off the gas I'm reading 11.15% and 72.2%. I was under the impression at zero throttle I was looking at 14% maybe 15 and it wide open throttle 75 because of how the computer reads the throttle position
Question 2: is it the correct procedure to adjust the Allen screw underneath the throttle linkage to achieve these results or is it something that has to be done in the ECM?Was considering 800-950 to help the AC a little bit and not have to feather the clutch in stop and go traffic, to make stop and go traffic a little more tolerable during DD commutes. 2006 6speed LJ. TIA.

 

[Steel City 06]

The idle RPM is adjusted only through the PCM. You’ll need HP Tuners to do that, and that’s pricey. (But you can change a lot of other things as well.)

Factory idle speed is programmed at 648 RPM without AC and 720 RPM with AC, though it will go higher if the engine is still not fully warmed up or is overheating.

Higher idle speed won’t hurt the engine at all, unless you set it stupid high. Very low idle (less than 600 RPM) can cause wear issues however. The only major effect from a higher idle is significantly higher fuel consumption.

 

[g.hayduke]

I would look for alternative solutions. Good window tint and insulated headliner can make a huge difference.

Personally, I would leave the factory idle settings alone. Messing with that to improve your A/C performance seems unwise. Just rev it a bit as needed, if needed. And do something about the hot top.

 

[Steel City 06]

There are a few other ways to make the AC colder, with varying degrees of success.

The biggest one is to switch to a hydrocarbon refrigerant such as a R290/600a blend (e.g., Envirosafe, Duracool). They’re actually both more powerful and more fuel efficient than R134a, and better for the environment. The caveat is these are flammable refrigerants (R290 is literally propane and R600a is isobutane) and there is a slight increase in risk there. Super common in Canada but not as much in the US. (Certainly don’t use it in a leaking system or if you like to get into road rage shootouts…)

Using a heavy duty fan clutch will have a slight benefit in AC temperatures as well due to the higher airflow, but it will only be maybe a 3-5 degree difference.

 

[LJ-MXer]

The idle RPM is adjusted only through the PCM. You’ll need HP Tuners to do that, and that’s pricey. (But you can change a lot of other things as well.)

Factory idle speed is programmed at 648 RPM without AC and 720 RPM with AC, though it will go higher if the engine is still not fully warmed up or is overheating.

Higher idle speed won’t hurt the engine at all, unless you set it stupid high. Very low idle (less than 600 RPM) can cause wear issues however. The only major effect from a higher idle is significantly higher fuel consumption.

Appreciate the response. Does adjusting that allen screw act not as an idle adjustment but to fine tune the throttle blade? Key on, engine off, pedal to the floor I'm only reading 72% and IIRC 75% should be WOT?

 

[LJ-MXer]

There are a few other ways to make the AC colder, with varying degrees of success.

The biggest one is to switch to a hydrocarbon refrigerant such as a R290/600a blend (e.g., Envirosafe, Duracool). They’re actually both more powerful and more fuel efficient than R134a, and better for the environment. The caveat is these are flammable refrigerants (R290 is literally propane and R600a is isobutane) and there is a slight increase in risk there. Super common in Canada but not as much in the US. (Certainly don’t use it in a leaking system or if you like to get into road rage shootouts…)

Using a heavy duty fan clutch will have a slight benefit in AC temperatures as well due to the higher airflow, but it will only be maybe a 3-5 degree difference.

System is tight, no leaks, pressures are ideal, it's just hot and humid. Researching Heavy duty and Severe duty fan clutches but Haydens quality control has allegedly been declining.

Anything special I need to take into consideration prior to switching refrigerants?

 

[LJ-MXer]

I would look for alternative solutions. Good window tint and insulated headliner can make a huge difference.

Personally, I would leave the factory idle settings alone. Messing with that to improve your A/C performance seems unwise. Just rev it a bit as needed, if needed. And do something about the hot top.

I've been thinking too hard about Hot Heads and DEIs headliners. Heard mixed reviews on the longevity of their adhesives and velcro.
Short term might go with a spider shade or something similar to create an air gap under the hard top.

 

[TJMexico]

... In Southwest Florida right now the heat index is 100 plus and the humidity hangs around 100%, and I have a hardtop that's uninsulated and hot to the touch. ...

Where I live we have heat (not heat index) of well over 100F daily. My hardtop is black. I don't want to deal with insulation, but I do plan on painting it a lighter color. One option is to paint the entire top (either myself or professionally) gray, the color of primer, more or less.

What I am leaning toward, though, is just painting the flat top of it a light gray. Seems like someone else here did that and it made a lot of difference. And you just do the very top so that it's not readily visible from street level. I can do that by myself, relatively inexpensively.

 

[LJ-MXer]

Where I live we have heat (not heat index) of well over 100F daily. My hardtop is black. I don't want to deal with insulation, but I do plan on painting it a lighter color. One option is to paint the entire top (either myself or professionally) gray, the color of primer, more or less.

What I am leaning toward, though, is just painting the flat top of it a light gray. Seems like someone else here did that and it made a lot of difference. And you just do the very top so that it's not readily visible from street level. I can do that by myself, relatively

 

[LJ-MXer]

Where I live we have heat (not heat index) of well over 100F daily. My hardtop is black. I don't want to deal with insulation, but I do plan on painting it a lighter color. One option is to paint the entire top (either myself or professionally) gray, the color of primer, more or less.

What I am leaning toward, though, is just painting the flat top of it a light gray. Seems like someone else here did that and it made a lot of difference. And you just do the very top so that it's not readily visible from street level. I can do that by myself, relatively inexpensively.

Can't look any worse than my original "Bright Metallic Silver" paint that's never seen a garage and a fair share of tight trails!

 

[LJ-MXer]

Would an additional, electric pusher fan, infront of the condenser do more harm than good?

 

[LJ-MXer]

Would an additional, electric pusher fan, infront of the condenser do more harm than good?

 

[Steel City 06]

Appreciate the response. Does adjusting that allen screw act not as an idle adjustment but to fine tune the throttle blade? Key on, engine off, pedal to the floor I'm only reading 72% and IIRC 75% should be WOT?

Nope. Idle is controlled through the idle air controller, which bypasses the throttle plate.

All adjusting the screw is going to do is create an apparent vacuum leak that will cause the engine to run rough and throw a check engine light. Might even go into limp mode if it's bad enough.

The throttle position sensor doesn't go from 0-100%. It's usually in the range of 13.7% to 74.4% or something along those lines. That is normal. The PCM knows what those setpoints are so it knows to assume WOT at ~74% throttle. It's slightly different among rigs. (It's also actually interpreted as a voltage rather than a percentage by the PCM, and that relationship is not linear.)

 

[LJ-MXer]

Nope. Idle is controlled through the idle air controller, which bypasses the throttle plate.

All adjusting the screw is going to do is create an apparent vacuum leak that will cause the engine to run rough and throw a check engine light. Might even go into limp mode if it's bad enough.

The throttle position sensor doesn't go from 0-100%. It's usually in the range of 13.7% to 74.4% or something along those lines. That is normal. The PCM knows what those setpoints are so it knows to assume WOT at ~74% throttle. It's slightly different among rigs. (It's also actually interpreted as a voltage rather than a percentage by the

Nope. Idle is controlled through the idle air controller, which bypasses the throttle plate.

All adjusting the screw is going to do is create an apparent vacuum leak that will cause the engine to run rough and throw a check engine light. Might even go into limp mode if it's bad enough.

The throttle position sensor doesn't go from 0-100%. It's usually in the range of 13.7% to 74.4% or something along those lines. That is normal. The PCM knows what those setpoints are so it knows to assume WOT at ~74% throttle. It's slightly different among rigs. (It's also actually interpreted as a voltage rather than a percentage by the PCM, and that relationship is not linear.)

Thanks. I knew it was voltage just wasn't sure abour the exact voltage numbers.

 

[ColoJeep]

Where I live we have heat (not heat index) of well over 100F daily. My hardtop is black. I don't want to deal with insulation, but I do plan on painting it a lighter color. One option is to paint the entire top (either myself or professionally) gray, the color of primer, more or less.

What I am leaning toward, though, is just painting the flat top of it a light gray. Seems like someone else here did that and it made a lot of difference. And you just do the very top so that it's not readily visible from street level. I can do that by myself, relatively inexpensively.

I color changed the hardtop from black to desert tan . It made a big difference in interior temperature .

 

[KennethS]

Where I live we have heat (not heat index) of well over 100F daily.

Same here. Actual heat, not heat index that applies only to sweat based cooling systems.


I just push the pedal enough to bring the engine up to around 1100 RPM while I’m stopped in traffic. That keeps the vent temperature from rising while I’m sitting still.

 

[GoldenGorilla]

Question 1: is  how high is too high to set the idle without causing any damage to the engine? I THINK the manual is looking for 750rpms at 14%? Currently with the engine OFF with foot off the gas I'm reading 11.15% and 72.2%. I was under the impression at zero throttle I was looking at 14% maybe 15 and it wide open throttle 75 because of how the computer reads the throttle position

1.1 - I've bumped my idle up to 800 in HP Tuners because my MORE Bombproof motor mounts were transmitting the idle directly to the chassis and it was a bit choppy at the stock setting around 672 rpm. I noticed on fast warm up at 900 it was smooth so I tried a few increments til I got that and landed on 800 rpm.

1.2 - I noticed this oddity with the reported throttle position in Torque. I thought it might be compensating for IAC position, but am not sure. I do not see this variance in HP Tuners VCM Scanner. 0%-100%, no problems.

Question 2: is it the correct procedure to adjust the Allen screw underneath the throttle linkage to achieve these results or is it something that has to be done in the ECM?Was considering 800-950 to help the AC a little bit and not have to feather the clutch in stop and go traffic, to make stop and go traffic a little more tolerable during DD commutes. 2006 6speed LJ. TIA.

2 - You need to go through the PCM via HP Tuners MPVI3. Yes, it's pricey, but you can do other things with it like bump up timing at WOT a few degrees, or turbo your jeep, or... You want to let the ECM control the idle air controller (IAC), otherwise you'll just be causing yourself other headaches.

Aside from these, I installed a Boom Mat in my CO TJ years ago and it's great for reducing the hardtop heat radiating into the interior. I did it for the sound reduction, but the insulation factor is great too. Our temps don't get quite as high rarely getting over 102, but at 6000+ feet the solar intensity can be significant. It's not the easiest thing to install, but it works well.

 

[Zorba]

Install a hand throttle, and paint the top of the hard top white.

 

[LJ-MXer]

Install a hand throttle, and paint the top of the hard top white.

If I set the hand throttle to 1K the gas pedal will override it but will it settle back down to 1K when I let off the pedal?

 

[Zorba]

If I set the hand throttle to 1K the gas pedal will override it but will it settle back down to 1K when I let off the pedal?

Yes.