Okay, I Give Up, I Need Help!

[Comanche County]

Still getting a high idle upon start up. I've changed the TPS, MAP, and IAC. I sprayed soapy water trying to find a vacuum leak. I've put my eyeballs a few inches from every vacuum line and still, I'm getting a high idle upon start up. It's around 2.8-3k. Really annoying. It stopped for about a week and ran fine, now it's doing it again.

 

Any ideas?

 

Thanks,

Jay

[ComancheKid45]

Was the new TPS set to the correct voltage?

[jpnjim]

Check the wires leading to your TPS

I would get an intermittent high idle like that,

move the wires around a bit, and it would calm down.

 

On a different 4.0L it would take 20 seconds or so to start when cold,

always followed by a high idle, till the excess fuel pumped in cleared out.

 

On that Jeep,

turning the key forward to the run position for a few seconds before cracking 'cured' the problem.

 

On your Jeep,

I'd check the whole harness for obvious issues (tho sometimes you can't see it)

& look for a leaky injectors.

If you haven't yet,

taking the throttle body off, and completely cleaning it helps too.

Something might be intermittently stopping the IAC from moving.

[Pete M]

soapy water for a vacuum leak? :hmm: I've always used that for air escaping out (like a tire leak), not air going in. use a flammable substance like starter fluid or propane (unlit of course). when the vacuum sucks in it the leak, the engine rpms will change and alert you to the problem area. :thumbsup:

[Comanche County]

Thanks for the input guys. Still under the hood now. I've got the TPS adjusteded according to guru Cruiser's guidelines. Input and output voltage is within 17%. Now my idle is up to 4k!

 

You're right Pete, soapy water probably isn't the best for a sucking vacuum leak.

 

Kinda scratching my head right now.

[Comanche County]

Jim, if I can't figure this out tonight the I'll take the TB off and clean it good like you recommended.

[Comanche County]

Just took the TB off...cleaning it like a starving Pakistani now.

[Comanche County]

Cleaned the TB, still idling at 4k.

[Pete M]

tried the starter fluid yet? carb cleaner works too. heck, wd 40 might even work, but I recommend using something that evaporates cleanly and quickly. :thumbsup:

[Comanche County]

Yup, tried carb cleaner on all the tubes and hoses. Still idling around 3.5-4k.

 

I've decided to retire for the night and consume some hallucinatory beverages from the New Belgium brewery company and offer a small sacrificial offering to the jeep gods by placing multiple pins in a small voodoo doll of Kim Jun Un.

 

 

[ftpiercecracker1]

What would it do if you disconnected your TPS entirely?

[jpnjim]

You could also check to see if your intake manifold bolts are tight.

They do loosen up.

 

I also unplugged my TPS when diagnosing my issue,

I just can't remember what that did :)

 

I'm running out of ideas.

[ftpiercecracker1]

What would loose intake bolts have to do with excessively high idle? :hmm: Loss of vacuum?

[Biotex]

Any type of a vacuum leak causes a high idle.

[jpnjim]

What would loose intake bolts have to do with excessively high idle? :hmm: Loss of vacuum?

Yep,

big vacuum leak.

 

Crazy idles on Renix's are usually electrical issues,

but it still could be a mechanical/vacuum issue.

 

You said the idle races at start up,

does it calm down afterwards?

[88blackpearl]

My vacum block had a leak...I think....so i just straight hosed them together. It resolved my high problem.

[ftpiercecracker1]

....so i just straight hosed them together.

 

 

 

What ? :hmm: what do you mean straight hosed?

[mountainman]

Hes saying he bypassed the vac block. I'm renix impaired (and proud) so I'm of no help. lol.

[Goose]

Have you tried applying bfh?

[cruiser54]

Did you do the sensor ground test in my TPS write-up?

 

You did your 17% adjustment off the flat plug, right? Where output voltage is 17% of input voltage? Your description of your results has me concerned.

[Comanche County]

Did you do the sensor ground test in my TPS write-up?

 

You did your 17% adjustment off the flat plug, right? Where output voltage is 17% of input voltage? Your description of your results has me concerned.

 

Roger, I'm at 17%. It seemed to have settled down, no more 3-4K idling. But now its idling at 1200 rpms, still a tad high. One good thing happened though, probably from swapping the sensors, it is running noticeably better.

[cruiser54]

That's too high an idle. Has this always been a problem? Anyone ever mess with the throttle butterfly screw?

[Comanche County]

Nope, I've never touched it. I'll check it out in the morning.

[cruiser54]

So, it didn't have this issue when you got it?

[cruiser54]

Have you sprayed around the intake/hoses with throttle body cleaner to find vac leaks at idle? Ever done a ground refreshing?