1988 Jeep Cherokee curbside idle very high

Did the high idle just start since the manifold was replaced?

The only things I can think of is either a vacuum leak, idle air control valve, or throttle position sensor.

Mr./Miss/Mrs./Other Jay. Please read my profile and maybe some of my CJ5 & 7 Answers in their forums. Even read some of my other answers that pertain to Cyber-Rigs (such as yours). You will see why my wife and others call me, A/n/a/l

I do not know your plight here, but sometimes it gets really busy--I just play here, I am a member like you. That answers alot more. This is one of my hobbies now.

This site has been really a lifesaver for me.I broke my foot at work, and was "Reclinerized" for a long time.

This site gave me something to do and something to learn.I even pizz people off here too!

The worst thing about being a Cyber-Tech is, WE DO NOT KNOW WHAT YOU, OR YOUR EVIL BUDDY DID TO IT ALREADY. AND EVERYONE IS SCARED TO TELL, OR JUST FORGETS. This really throws in a new twist sometimes!

It's hard enough to explain stuff, while you are looking over their shoulder!

I am not a Backyard Mechanic.I am Better Than That!

I am a Self Certified Rear Lawn Vehicle Technician (SCRLVT) (sorta what you wanna be)

Ever since, even before I had my drivers license, I've strived for Perfection when repairing my, or anyone elses vehicle.'Cause I want to repair once. Not twice. And get the best efficiency at the same time!

Yes, I have pizzed off many people along the way, questioning their answers. But I didn't care. This is "MY STUFF" we are talking about. And It Matters alot to me. No Half-Azzing on my stuff. Or my Mom and Dads. Friends Etc!

My rigs. Have not been in a Pro-Shop, in over 15 years (probably longer than that). But I have, and I get the answers I need. Especially on the Cyber-Stuff (my weakness) I understand the "Mechanicals".I am not up to par on the sensors.I'm used to the Traditional Diagnoses (basically by ear). But the computer stuff CONTRADICTS. The Old Way alot.
Yes, You guessed right.I'm still PIZZING people off. To gain knowledge for myself.I even still find new places to gain my knowledge.I make the system, work for me!

I find the least expensive parts---Even if it means "Part Swapping" to diagnose--Inexpensively from a Salvage Yard. Just to verify the problem. Dependant on the part, I will PURCHASE a new one. Once it is Figgered out.

I do not like working on cars. Especially the new ones.I DO IT OUT OF NECESSITY.I DO NOT "TRUST" OTHERS ON "MY MACHINE"!

I am not rich---I have seen too many HORROR STORIES. Experienced 1st hand, in a company plumbing truck. Joe DUMB-AZZ changing the oil with an IMPACT WRENCH. Saw results on another rig (using the same "quick change oil place") The rubber plug they installed, fell out and my friend, destroyed her engine really fast. They had told her they were installing the plug, at the time (she had no clue. WHY? EXACTLY). But I do."IMPACT MAN. You can do damage with your bare hands too.I see too many, who do not care 'cause "IT AIN'T THEIRS"

So, now down to you.I do not know your rig. But my Dad has a '86 Thunderbird. Close in years to you. So It may have similar systems!

He (we) Had a Idle problem on it. So you know whats I duzz. Crank on the throttle body Idle screw. Wrong! I just totally messed up "BASE IDLE!"

Now I have 2 problems----that are creating even more problems."Base Idle" is the STANDARD THROTTLE SETTING in which everthing is calibrated to (other sensors, thru Mr. Computer). So now other issues arise 'cause stuff ain't "In Sync", and I am pulling my hair out.I was ignorant, and knew no better.I did learn, it does't work like the old stuff!

Tune in tomorrow, with a reply, And I will continue my Novel. Its not too much longer, as to what I learned, and how to overcome it. How to get base Idle right again.

Gotta go help my Pap, go to Doc, having the chemo stuff, is very weak. Traveling 30 miles to get to his house.

Respond

The Medic

OK JAY, Just so you know.

You have now been dealing with 2 people at this site,

1st Guy. JacobandNicholas (ASE certified mechanic-really knows newer rigs)

2nd Guy, Me, SELF CERTIFIED REAR LAWN VEHICLE TECHNICIAN.I have earned "Helper Status" and I know my CJ Jeeps well.I do understand other vehicles, but I really only answer, if I think its within my capabilities.1ST guy is probably laughing at my ignorance of newer rigs!

I answered you, because I saw you were "Unhappy", to say the least.I thought maybe I could help with some input. Since I had spent so many hours researching the '86 T-Bird (close in years w/ yours, maybe w/same type systems.)

EVERY TIME SOMEONE ANSWERS A POST, ALL INVOLVED GET A AN ALERT, AND YOUR POST COMES TO THE TOP!

So, Jacobandnicholas. Is monitoring this as well, he may be your best bet as far as Computer Rigs go.

Information in detail, is our best friend, as far as helping anyone

. So Do you have throttle body fuel injection?

Have you messed with the idle adjustment?

Have you/ or do you have a THROTTLE POSITIONER (not throttle positioning switch, you'll have that too, maybe) on your body? (I was shown the EZ way to reestablish BASE IDLE, and "Zero In" the positioner again should your system be similar to my Dads, IF NEED-BE for your too.)

Regardless--answer the questions and any other info you can muster.

A Repair manual as mentioned in my profile may aid you in I.D. Ing stuff, and be useful for future SCHEDULED MAINTENECE and Repairs, keep it in your rig. Someone else may be able to use it to help you!

I'M GONNA GIVE THE OTHER GUY (J & N) A CHANCE TO GIVE YOU A BETTER ANSWER THAN I, BUT I WILL COME BACK SHOULD HE NOT RESPOND IN A DAY OR SO.

REMEMBER US IN "FEED BACK" GIVES THE NEXT POOR VICTIM A GLIMPSE OF THEIR ANSWERER!

DON'T GIVE UP ON US YET!

THE MEDIC

Jayanne,

I am so sorry. I never received a follow up for some reason. I have to thank CJ Medevac for bringing it to my attention. When there is a follow up from a customer, I receive a notification via my email, but this time I never got one. I always respond within one day of receiving notification. Again, sorry about that.

As far as the idle issue, don't replace the throttle position sensor if it was checked and okay. I really think you have a vacuum issue we are dealing with at this point. Have you checked the EGR to make sure it isn't clogged with carbon?

Let me know. (I will keep this in my mail. If I don't hear from you in the next couple days, I'll get back to you.)

Joe

Hi Jay,

If the 3 sensors are connected wrongly at the the intake manifold, they can cause the engine to perform erratically.

What are the wire colors for each of the connectors?

Did you try to adjust the ISA?

You mentioned taking pictures of the parts around the throttle body, that should help.

I got this message. Yes, if they were connected in the wrong place it would cause the engine to act irratic.

Here is what I can tell you about the tps. It usually won't have an affect on the base idle but as soon as you hit the gas is when the problem would start. That is what is making me lean toward a vacuum leak. It doesn't have to be a vacuum hose. It could be the actual intake itself, loose throttle body.

I checked a schematic and everything looks correct. I hate to say it, but I'm at a loss. If you disconnect the idle speed motor, does that change anything?

FYI: I'm going to ask another tech to look at this and see what he says.

Let me know.

Joe

I hate to butt in, Buuuuuuuut,

When I messed up base Idle on my Dad's T-Bird ('86 3.8L) The procedure I was shown to get it back was:

1) Crank up, get to operating temp

2) I Shoved my finger inbetween the Throttle Tab on the Throttle body and the "Throttle Positioner"?

3) When I did that, the "Positioner" Backed up on its own, As I "RODE" it down with my finger.
(It was trying to reduce the RPMs, I created w/ my ONE finger, holding throttle open, and simutaniouly, slight pressure on the Positioner)

4) As soon as it backed all the way up (bottomed itself out), My BUDDY UNPLUGGED IT. Now it was out of the way!

5) Then using my Dwell/ Tach Meter, I adjusted the IDLE SCREW (That I Messed With, in the beginning!)

6) I believe I set The FORD's (Base)Idle to 400 RPM (whatever it was supposed to be, according to our reference)

7) Then we plugged the positioner back in

8) SUPPOSEDLY, as the "Positioner" pushed itself back out, and CONTACTED the "Throttle TAB".

9) When it TOUCHED the tab, It had "ZEROED" itself to the system.(Now calibrated!)

10) Everything seemed, "GOOD TO GO", on Pap's car.

Is this the correct way to do it?

Will it work for Jay?

DO NOT DO THIS, JAY, UNLESS J&N TELLS YOU TO!

The Medic

Try dropping the idle speed thru the ISA-plunger

Adjustments

This adjustment is only required after the ISA motor has been replaced, and is only used to establish the initial position of the actuator.

NOTE:An ISA Exerciser Tool (Part No. Ele. AB.99) is required to successfully complete the adjustment of the ISA motor. Slight modification to the ISA Exerciser Tool (Part No. Ele. AB.99) connector may be required so that it can be connected to the ISA motor. Use a hobby knife, and cut grooves in the casing of terminal (A) that match the grooves in the terminal casing of terminals (D) and (B).

Disconnect and remove the air inlet bonnet.
Start the engine and allow it to reach normal operating temperature.
Turn air conditioning to OFF position.
Diagnostic Connector Identification

Connect a tachometer across diagnostic connector D1 terminals 1 and 3.
Disconnect the Idle Speed Actuator (ISA) electrical connector from the motor.
Connect the ISA Exerciser Tool (Part No. Ele. AB.99) to the ISA motor.
Using the Exerciser Tool, extend the ISA plunger fully.
Idle Speed Actuator (ISA) Motor Adjustment

Turn the Adjustment screw, while watching the tachometer, until the engine speed is 3500 rpm.
Disconnect and remove the ISA Exerciser Tool (Part No. Ele. AB.99) and connect the ISA electrical connector. Idle speed should return to normal after a few seconds.
Re-install air inlet bonnet.