My 87 I6 has developed an intermittent high idle. No tach, so I don't have the RPMs, but it acts as though I have it floored. It's hard to keep it still with the brake on the floor.

It was running fine until about two weeks ago. It started this once or twice when the tank was near empty. Now it's doing it on a daily basis regardless of fuel level.

If I turn it off and restart it, it will occasionally act normal.

The IAC, TPS and MAP Sensor were replaced about three months ago.

Thoughts?

 

vacuum leak probably or loose bolts on the intake manifold allowing for a inconsistent air/fuel ratio.

 

pull your iac and tps again and make sure they are clean, ive seen new iac's act up.. i sprayed mine down with carb cleaner and wiped clean gently.

 

What brand tps did you use? I have had an autozone tps last less than 3 weeks and exhibit high idle symptoms.

 

# thoughts.
Did you adjust the new TPS?
Have you ever refreshied your grounds, checked the sensor ground circuit?
Have you refreshed the c101 connector?

 

yes, the tps was adjusted and the grounds are refreshed and the circuit is good. I have not refreshed the c101 connector.

I'm leaning towards the IAC. I'm going to clean it today and see if that helps.

 

Good. Then do the c101 anyway becuase it's such a source of problems.

 

Cruiser I have a dumb question for you. What is the c101? I see this often but have no idea what it is.

 

Renix Jeep C101 Connector Refreshing
　
The C101 connector on 1987 and 1988 Renix Jeeps was a source of electrical resistance when the vehicles were new. So much so that the factory eliminated this connector in the 1989 and 1990 models. The factory recommended cleaning this connector to insure the proper voltage and ground signals between the ECU and the fuel injection sensors. We can only imagine how this connector has become a larger source of voltage loss and increased resistance over a period of almost 25 years. The C101 connector needs to be cleaned at least once in the lifetime of your vehicle. Chances are it’s never been done before.

Almost every critical signal between the engine sensors, injectors, ECU, and some to the TCU, travel this path through the C101 connector.
The C101 connector is located on the driver’s side firewall above and behind the brake booster. It is held together with a single bolt in it’s center. To get the connectors apart, simply remove the bolt and pull the halves apart. You will find the connector is packed with a black tar like substance which has hardened over time.
Take a pocket screwdriver or the like and scrape out all the tar crap you can. Follow up by spraying out both connector halves with brake cleaner and then swabbing out the remainder of the tar. Repeat this procedure until the tar is totally removed. This may require 3 or more repetitions. Wipe out the connectors after spraying with a soft cloth.
If you have a small pick or dental tool, tweak the female connectors on the one side so they grab the pins on the opposite side a bit tighter before bolting both halves back together.
　
Revised 07-17-2012

 

Thank!
Now I know why I have never ran across a problem with it. All my XJ's range from 1992-1998.
Good to know.
Thanks again.