High rpm?

[Dave88]

Trucks runnning now but its at, id say 3100 rpm. I think this mught be the starter fluid i put in the intake am i right?

[BLHTAZ]

It could be, but if that were the case, it should burn off in a very short time and come back to normal. If it is staying that high, you have a problem somewhere else...possibly the IAC or TPS. If the IAC is sticking, sometimes you can "tap lightly" on the side of it with a wrench or ratchet and it will release and bring the idle down. If that happens, you need a new one.

[Dave88]

I put it in drive and it started spinnin the tires. scared the $#!& out of me because my house was just feet away.

[chicofuentes0224]

My two guesses are that the IAC is sticking or the arm on your throttle body is. Where did you spray the starter fluid? In the throttle body?

Checkfirst to see if the arm is sticking.

If it's not then check the IAC. If you look at the throttle body from the front there's two sensors attached. It's the one with a diamond shaped backing plate up against the throttle body. Don't bother trying to clean it. Go pick up a new one at the auto parts store.

It's listed as either IAC, iddle stepper motor, or idle air control valve.

If the throttle arm is sticking lube it up with PB blaster.

[Dave88]

Nothings sticking, i can tell by looking the throttles not even being pulled.

Starter fluid went into the intake.

[chicofuentes0224]

Then your IAC is probably shot.

Change it out for a new one.

Here's a pic.

 

 

It's the one on the left.

[Dave88]

alright, ill do that if i have problems ill just post in here again.

[chicofuentes0224]

Before I forget, clean out your throttle body with throttle body cleaner. You probably loosened up the carbon buildup with the starter fluid and it's jammin up where the sensors go.

[Dave88]

I think your right, i unplugged the ISC, then started it and nothing changed. Ill buy some today.

[fatcat0491]

Mine Was Having a high idle to. What i did was i even looked at the throttle cable, and it worked fine, But it was held open Just a Lil and that lil goes a long way's. I put a spring from my throttle body linkage to a Piece of metal So that it would snap Shut as soon as my foot was off the pedel.

[Dave88]

I can't even sit in drive without the tires spinning.

[Kenosha Warrior]

First of all, stop putting it in drive, too much High-RPM engagement will crack the case or worse.

 

 

Second of all, Go over your VAC lines. 3100 RPM is fairly high for a 4.o and a good sized Vac leak would do it.

[Pete M]

I had that problem in my 90 and it turned out that the throttle cable wasn't returning and that left the throttle plate open a bit. I'd recommend pulling off the filter box and tube so you can visually check that the throttle body plate is indeed closed at idle. 8)

[james750]

Based on you putting 2 cycle oil in it and now its doing it i would say really dirty injectors. I had this same problem about a month ago and it turned out that I had 3 injectors sticking open. its pretty cheap to fix, either replace injectors (recommended) or go to a shop and they can pressure clean them for you.

[Dave88]

@pete i would do that but i never took the tube off before, and i doubt its ever been taken off. the screw are like welded on there. :mad:

[Dave88]

@james when i first got it running it smoked up for about 3 minutes now it hasnt smoekd at all, i think it just flushed all the $#!& out of them.

[Pete M]

@pete i would do that but i never took the tube off before, and i doubt its ever been taken off. the screw are like welded on there. :mad:

 

Just to clarify, I'm talking about removing the rubber air duct going from the filter to the throttle body. Use the PB blaster and be patient with it. It'll come off eventually. :D

[Eagle]

Nothings sticking, i can tell by looking the throttles not even being pulled.

Starter fluid went into the intake.

No, you cannot tell by looking.

 

The accelerator pedal cable leads to a "bellcrank" linkage that's down low on the left (driver's) side of the engine. There's a vertical rod that comes up from that bellcrank to the upper end that operates the arm on the throttle body. That lower bellcrank can get rusted and nasty, which results in the throttle sometimes not returning to the idle position. It has happened to me twice. You can't see it -- it doesn't look like there's anything wrong. But after spraying liberally with PB Blaster and working the linkage some, my idle went back to normal.

 

That's not the only cause of a high idle, of course. The other ... and more likely ... cause is the idle air controller (IAC), which has already been mentioned to you.

[Dave88]

"The other ... and more likely ... cause is the idle air controller (IAC), which has already been mentioned to you."

 

Thats what I'm going to do.

[chicofuentes0224]

The other ... and more likely ... cause is the idle air controller (IAC), which has already been mentioned to you.

 

Thats what I'm going to do.

 

Yes Dave but sticking a new IAC in there is worthless without a good cleaning first.

 

1) Disconnect the air tube going from the airfilter to the throttle body.

2)Remove your IAC

3) I'd tell you to remove the TPS next but only if you have the means to properly adjust it when you put it back on.

Run a search on here on how to adjust your TPS.

4) Clean out the throttle body, especially where the IAC goes in.

5) Buy your new IAC and plug everything back in.

 

Then if you have any more problems we can discuss more options down the line.

Question: Is the engine now running smoothly (besides the fact that it's at 3100 RPM?

[Pete M]

Be sure to use a "throttle body cleaner" on the throttle body or one that says it's safe for Throttle bodies. Many "carb cleaners" aren't O2 sensor save.

[chicofuentes0224]

Be sure to use a "throttle body cleaner" on the throttle body or one that says it's safe for Throttle bodies. Many "carb cleaners" aren't O2 sensor save.

 

Times one million! DO NOT USE CARB CLEANER!

We're gonna stop adding more problems right here :D

[Dave88]

its real smooth. yea. and my oxygen sensor is busted. its been saying "emmis mait" since i bought the truck. i knwo how to fix that tho.

[Pete M]

That light is on a timer. It's not actually connected to the engine or computer at all. There's a small plastic box under the dash on the drivers side with little gears in it. Yank it out. The older MJs don't have a way of telling you that the o2 sensor is bad.

[Eagle]

its real smooth. yea. and my oxygen sensor is busted. its been saying "emmis mait" since i bought the truck. i knwo how to fix that tho.

You "fix" the light by unplugging the timer box. But as Pete wrote, the timer is not a tester. The only way to test your oxygen sensor is to hook the truck up to a sniffer and see if it's running rich. The O2 sensor is supposed to be replaced every 75,000 miles. The conservative approach when buying a used truck is to assume it's due and replace it. If it improves your fuel economy by a couple of MPG, at today's gas prices the new one will pay for itself quickly.