2008 JKU revs

awdel87

New member
I have a 2008 JKU that revs up to 1200rpm when park, I want to know what could cause this to happen, I when to a mechanic and told me the JK does not have a iac, when I ask about the iac going wrong. I did oil change and tps is new too.
 
I have a 2008 JKU that revs up to 1200rpm when park, I want to know what could cause this to happen, I when to a mechanic and told me the JK does not have a iac, when I ask about the iac going wrong. I did oil change and tps is new too.

Is your gas pedal catching at all?
 
Every time you park?

I have a 2008 JKU that revs up to 1200rpm when park, I want to know what could cause this to happen, I when to a mechanic and told me the JK does not have a iac, when I ask about the iac going wrong. I did oil change and tps is new too.

Does it do it every single time it is in park or only after its been driven? If it is only after it has been driven does it do it after short easy drives or only after long or hard drives (like lots of elevation gain on a hot day)?
 
It's basically when I turn it on, it keeps going hight and low, it's my first JK, so I don't have an idea if is normal or not.
 
It's basically when I turn it on, it keeps going hight and low, it's my first JK, so I don't have an idea if is normal or not.

Ok, so when you turn it on you notice it upping the revving. Now does it do this revving after you've driven it for say 20 minutes, long enough for it to warm up a bit, and then put it in park?

The reason I ask that is because my 08 starts out idling high when i first turn it on. After a bit it will start to settle down and drop to what is it's normal idle, but it does go through a bit of a song and dance before it settles down. That being said once I start driving it around and put it in park there is no issue with above 'normal' idle revs - it only happens when its cold started. I don't know if that fits your profile or not, but that's what mine does. It's also got some other not so pleasant growling sounds before it warms up as well, but thats another story. Let me know if your issue is the same or different if you would.
 
...... and tps is new too.

are you sure you have the correct tps? did you double check installation and make sure the tps arm Is under the throttle lever properly and the lever is not hanging on something?

you might try resetting the ecu by disconnecting both ground and positive for at least 20 minutes.

you may have to take it in to the dealer to have them adjust the tps
 
Ok, so when you turn it on you notice it upping the revving. Now does it do this revving after you've driven it for say 20 minutes, long enough for it to warm up a bit, and then put it in park?

The reason I ask that is because my 08 starts out idling high when i first turn it on. After a bit it will start to settle down and drop to what is it's normal idle, but it does go through a bit of a song and dance before it settles down. That being said once I start driving it around and put it in park there is no issue with above 'normal' idle revs - it only happens when its cold started. I don't know if that fits your profile or not, but that's what mine does. It's also got some other not so pleasant growling sounds before it warms up as well, but thats another story. Let me know if your issue is the same or different if you would.

X2. Both my 2012 JKUR and '92 MJ do the very same thing. I've been told an ice cold engine at start up and normal idle is a bit dirty so while the CPU is getting out of bed like the engine the extra rpm's keep the emissions a little cleaner. I could be in left field here, but it sounds like a reasonable explanation.:twocents:
 
Solved?

X2. Both my 2012 JKUR and '92 MJ do the very same thing. I've been told an ice cold engine at start up and normal idle is a bit dirty so while the CPU is getting out of bed like the engine the extra rpm's keep the emissions a little cleaner. I could be in left field here, but it sounds like a reasonable explanation.:twocents:

^^ Sounds reasonable to me.

For the OP I paid attention to the starting RPMs this morning and sure enough it was hanging out around 1200 RPMs until I pressed on the gas a couple times and it went back below 1000 RPMs to its 'normal' idle. It seens to be quite normal during a cold start and the actual reasons are probably what Linebacker said I'd bet.
 
Cool, then it's normal in my JK too, now I always heard a small sound every time I turn the steering wheel.
 
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