high idle (before & after cleaning IAC)

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My truck was idling pretty high (not sure of the rpm, no tach), so I searched the forum and found the info on cleaning the IAC. Cleaned up the sensor, cleaned the passage and gave the throttle body a good bath. It's still idling high. Bad IAC valve or maybe a vacuum leak?

 

The RPMs increase when I press on the brake pedal. I found a plugged vacuum line going from the EGR to a metal disk shaped doohickey that is attached to the driver side below the top of the throttle body.

[Oizarod115]

:idea: DON'T DRIVE THE TRUCK LIKE THIS,

but, try removing the vacuum line to the brake booster, and plugging that port. see if that fixes the high idle.

if the booster is going bad you could be getting air in through it which would explain the brake pedal affecting the idle-speed.

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:... plugging that port. see if that fixes the high idle....

 

Bingo! Thanks for the tip! Looks like I'll be getting a new booster. Is there any (like off a ZJ) that would be an "upgrade"? After I found that plugged line, I decided to check all the vacuum lines once the weather gets a bit warmer. Little too frosty to be yanking on rubber hoses in my unheated garage.

[Oizarod115]

a 95-96 cherokee booster is a bolt-in swap, but you will need to bend new brake lines to go from the master-prop valve (also two metric-standard adapter fittings) lookin about like 25-30 bucks in brake lines (high estimate) and you'll need booster, master cylinder and either a different brake light switch setup or drill the rod out and make it fit.

[Wildman]

Also........if you found the vacuum line to the EGR capped off, more than likely, the EGR valve is not working, and really no worries about that.

 

If you want to check it, just plug the vacuum line in to the EGR valve while the engine is running, if it's malfunctioning, it will choke the engine right out.

 

I agree with the upgrade for the brake booster.......and here's a write up for it -

 

http://www.madxj.com/MADXJ/technical/te ... pgrade.htm

[maddzz1]

if you do the booster upgrade grab the pedal assembly with the bracket and newer brake switch too. If you have a standard it will be adirect swap, you just have to splice the two wires for the brake switch. If you have an automatic it is a bit different. the shift cable for the tranny is on the brake pedal bracket for the mj. which also makes this a good time to switch to a floor shift.

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Thanks guys! Looks like I'll be swapping in the double diaphragm booster once ye olde tax check comes in. A new booster and rotors/pads should greatly improve my stopping ability! While I'm under there might as well track down the cause of the play in my steering wheel. Do you think a junkyard booster is a safe bet or should I go with a remanufactured one?

 

 

This board is a life saver, you guys are packed full of great info. I've been on other auto/bike boards and found a lot of people that weren't very helpful or had the "if you have to ask, you shouldn't be doing it" attitude.

[Wildman]

Unless your pockets are very deep........I'd go the JY route, just check the mileage on the donor, I'm sure you don't want to grab a vital part off some thing that has over 200K on the clock :eek:

 

Me......I'm kind of annual on the brakes, look, your MJ is 22 year old, all the lines are that old (in most cases) or they been "patched" by others, so, re-doing the brake lines, replace all the soft lines, and Yes, replace the rotors, pads, and calipers are high on my list.

 

Plus, don't neglect the rear brakes, the lines that run behind the gas tank are Very prone to rot out. Oh, and then the load leveler :roll: One of the items that in my neck of the woods don't hold up, so that needs to be addressed. Then you have the soft line in the rear, and the wheel cylinders.

 

My point, I'd radder do the complete brake system all at once, get everything new and fresh, knowing that there is not going to be a problem down the road, and improve the stopping power over all, Then move on to the "other" upgrades :D

 

You mention "play" in the steering wheel?? as in loose steering column, or steering wheel moves 1/2 turn before the wheels move?? Yea, check that out to see what your problem is, it could be caused by several different items.

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You mention "play" in the steering wheel?? as in loose steering column, or steering wheel moves 1/2 turn before the wheels move?? Yea, check that out to see what your problem is, it could be caused by several different items.

 

You can turn the steering wheel side to side w/o getting movement from the wheels.

[Wildman]

That's what I was wondering :hmm:

 

Yea, better check that out, it could be the steering gear (box) is worn out :(

 

Time for the up grade :brows:

 

viewtopic.php?f=2&t=15106

 

Or a Durango steering box :D

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That's what I was wondering :hmm:

 

Yea, better check that out, it could be the steering gear (box) is worn out :(

 

Time for the up grade :brows:

 

viewtopic.php?f=2&t=15106

 

Or a Durango steering box :D

 

I've got a grocery list for the Junk Yard now! Looks like I"ll pick up a '95 ZJ box while I'm getting the XJ steering box. Thanks for all the help! :D