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High Idle


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I noticed a few times over the past several weeks that when I first fired her off it went to a really high idle. I tried pumping the gas pedal but wound up having to turn her off and restart it which cleared it. I’ve been so busy with other things like the ac, brakes, and just finished up a RMS replacement that I just added to my list of items to check. 

 

Well I let her sit over nite to allow the anaerobic sealer I used on the RMS r&r to cure and it did the same thing only this time I couldn’t get it out of the high idle situation by turning her off. I’ve visually checked over the throttle linkage to look for any binding but don’t see anything. 

 

Any ideas on what look at next appreciated. 

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7 minutes ago, Griff04 said:

I noticed a few times over the past several weeks that when I first fired her off it went to a really high idle. I tried pumping the gas pedal but wound up having to turn her off and restart it which cleared it. I’ve been so busy with other things like the ac, brakes, and just finished up a RMS replacement that I just added to my list of items to check. 

 

Well I let her sit over nite to allow the anaerobic sealer I used on the RMS r&r to cure and it did the same thing only this time I couldn’t get it out of the high idle situation by turning her off. I’ve visually checked over the throttle linkage to look for any binding but don’t see anything. 

 

Any ideas on what look at next appreciated. 

 

So she sit for a few minutes while I was typing this post, went back and restarted and the idle is fine??  Not sure what the heck is going on!!!

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1 hour ago, HOrnbrod said:

Remove the throttle body and clean. Replace and lubricate throttle linkage and cable. I like to use a dry cable lube like the below for this. If no help try adjusting the TPS.

 

31gEcx2m+3L.jpg

Will add this to my list...

 

Thanks,

Griff04

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If it's an 87 to 90, the TPS is probably going bad.

 

But, before firing the parts cannon at it, check the sensor grounds.

 

The sensor ground circuit affects the CTS, TPS, IAT, MAP, ECU and diagnostic connector grounds. It’s very important and not something to overlook in diagnosing your Renix Jeep as it is common for the harnesses to have poor crimps causing poor grounds. If any or all of the sensors do not have a good ground, the signal the ECU receives from these sensors is inaccurate.

Set your meter to measure Ohms. Be sure the ignition is in the OFF position. Using the positive (red) lead of your ohmmeter, probe the B terminal of the flat 3 wire connector of the TPS . The letters are embossed on the connector itself.Backprobe 2

Touch the black lead of your meter to the negative battery post. Wiggle the wiring harness where it runs parallel to the valve cover and also near the MAP sensor mounted on the firewall. If you have an 87 or 88 with the C101 connector mounted on the firewall above the brake booster, wiggle it, too.

You want to see as close to 0 ohms of resistance as possible. And when wiggling the harnesses/connectors the resistance value should stay low. If there is a variance in the values when wiggling the wires, you have a poor crimp/connection in the wiring harness or a poor ground at the engine dipstick tube stud.

Refreshing of the dipstick tube connection is covered in Renix Ground Refreshing, and the sensor ground upgrade is covered in Tip #6 – Sensor Ground Upgrade.

On 87 and 88 models, you could have a poor connection at the C101 connector as well. See Tip #2 – C101 Refreshing and Tip #27 – C101 Elimination.

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11 hours ago, cruiser54 said:

If it's an 87 to 90, the TPS is probably going bad.

 

But, before firing the parts cannon at it, check the sensor grounds.

 

The sensor ground circuit affects the CTS, TPS, IAT, MAP, ECU and diagnostic connector grounds. It’s very important and not something to overlook in diagnosing your Renix Jeep as it is common for the harnesses to have poor crimps causing poor grounds. If any or all of the sensors do not have a good ground, the signal the ECU receives from these sensors is inaccurate.

Set your meter to measure Ohms. Be sure the ignition is in the OFF position. Using the positive (red) lead of your ohmmeter, probe the B terminal of the flat 3 wire connector of the TPS . The letters are embossed on the connector itself.Backprobe 2

Touch the black lead of your meter to the negative battery post. Wiggle the wiring harness where it runs parallel to the valve cover and also near the MAP sensor mounted on the firewall. If you have an 87 or 88 with the C101 connector mounted on the firewall above the brake booster, wiggle it, too.

You want to see as close to 0 ohms of resistance as possible. And when wiggling the harnesses/connectors the resistance value should stay low. If there is a variance in the values when wiggling the wires, you have a poor crimp/connection in the wiring harness or a poor ground at the engine dipstick tube stud.

Refreshing of the dipstick tube connection is covered in Renix Ground Refreshing, and the sensor ground upgrade is covered in Tip #6 – Sensor Ground Upgrade.

On 87 and 88 models, you could have a poor connection at the C101 connector as well. See Tip #2 – C101 Refreshing and Tip #27 – C101 Elimination.

 

Thanks Cruiser, will definitely look at this. Been a long day, spent most of the day at the deer camp then came home grabbed the g-kids and took them out on the river tubing. 

 

Gonna sit back and chill the rest of the evening. 

 

Aprreciate everyone’s input. 

 

Griff04

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Got the throttle body off today...had quite a bit of build-up all through out it. Got it cleaned up, 3 cans CRC throttle body cleaner, and then reinstalled. Actually idles a lot better now, we will see if the high idle rears it’s ugly head again. 

 

For what’s its worth, no I’m not affiliated with them but I’ve using the CRC products for several years now, they work great, the degreaser product is probably the best I’ve ever used. I work in an industrial maintence environment and have seen a lot of different cleaning products come and go, this has been a go-to for our industrial cleaning needs. Just thought I’d throw that out there.....,

 

Griff04

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19 hours ago, Griff04 said:

Got the throttle body off today...had quite a bit of build-up all through out it. Got it cleaned up, 3 cans CRC throttle body cleaner, and then reinstalled. Actually idles a lot better now, we will see if the high idle rears it’s ugly head again. 

 

For what’s its worth, no I’m not affiliated with them but I’ve using the CRC products for several years now, they work great, the degreaser product is probably the best I’ve ever used. I work in an industrial maintence environment and have seen a lot of different cleaning products come and go, this has been a go-to for our industrial cleaning needs. Just thought I’d throw that out there.....,

 

Griff04

Agree on CRC. Have you tried their Freeze-Off penetrating spray?

 

 

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2 hours ago, cruiser54 said:

Agree on CRC. Have you tried their Freeze-Off penetrating spray?

 

 

I personally havent tried it but the guys in the rebuild shop use it all the time. They start complaining everytime a new vendor comes in the plant peddling new products, they are diehard CRC fans...they tell me all the time, whatever you do don’t take our CRC products away. Lol

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