Unusual idle problem

[danjeep]

Goodmorning,

After having some fun on the weekend, I noticed while driving home that when I am slowing down say for a set of traffic lights when I put the clutch in the revs drop down to say around 300rpm and then it revs itself a little to about 1000rpm and then comes back to idle. Has anyone seen or had this problem before if so how did you remedy it? Its still under warranty but I don't want to have to take it there if it is an easy fix I can do myself. BTW I have a 2005 Sport manual.

Thanks in advance

Cheers

Dan

[stu]

from what ive been told is sound like a faulty o2 sensor....where the jeep computer puts too little fuel in the mix because of a faulty reading then over corrects this problem by putting in too much fuel...it then discovers its putting in too much fuel and corrects the problem by starving the motor which starts the problem over again.

[Jeff]

Is your speedo working correctly? Had a similar fault when the speedo gear was a bit loose.

[Wooders]

Could be one of too many things - if you've got the warranty you can claim then go for it.....although I am not sure if the O2 Sensor is classified as warrantable ;)

[danjeep]

I am pretty sure my speedo is working normally, how much approx is an o2 sensor? How do you reset the computer?

Thanks

Dan

[Maddragon]

had a simular problem a few weeks ago. had to get a new throttle sensor ($294 + labour). the check engine light would keep coming on too. working great again now.

[Jonesy]

Throttle postion sensor

[jun180]

I am pretty sure my speedo is working normally, how much approx is an o2 sensor? How do you reset the computer?

Thanks

Dan

from what i have heard to reset the computer unhook the batteries and turn the lights on let it drain the spare charge out of the system. let it sit for 15 min or so then start her up again...but im not 100% sure

[Wallace]

you dont need to turn the lights on. Just take the positive off the battery and go inside for 10-15minutes. Go back out and connect her back up (make sure to do it in one go... so as not to create sparks and what not).

Start her up and thats how you reset the computer.

Although - im doubting this will fix the problem you mentioned. BUT.... anything is worth a go i guess.

Thanks
Will

[danjeep]

I reset the computer, checked if there were any error codes and all that comes up is "done" so i assume that means no error codes, and I haven't seen the engine light come on, looks like I'm going have to take it to the dealer let them sort it out

Thanks for the help

Cheers

Dan

[krankieone]

Mine does it after swiming goes away after a couple of days

[MR EXTREME JEEP]

Mine does it but I ignore it.:roll::wall:

[danjeep]

Mine does it after swiming goes away after a couple of days

I did a river crossing on the weekend, so that maybe the problem???

[huub]

Could be one of too many things - if you've got the warranty you can claim then go for it.....although I am not sure if the O2 Sensor is classified as warrantable ;)

just for your information had my o2 sensor replaced and yes it is warrantable
atleast my stealership didnt charge me to replace mine

[MR EXTREME JEEP]

just for your information had my o2 sensor replaced and yes it is warrantable
atleast my stealership didnt charge me to replace mine
HArdly called a stearlership in that case.

[Barefoot]

Mine occasionally does the same thing,my 02 sensor is being replaced under warranty shortly so I'll see if it fixes it.

[Locked Lizard]

Did a search and found this problem. I too, seem to have joined this club. I do alot of water crossings and I reckon that may be the cause as well. I sprayed a heap of crc around and seemed to fix problem for abit. I went out again 2 weeks later and got wet, and problem starts up again. I have 2 questions

1: Is it worth replacing this sensor? or when it get's wet it'll just happen again?

2: Where is the sensor? so I know which one to spray with crc to help prevent this happening again. Someone have a photo or great explanation of which one it is?

3: Does anyone have a good idea to help prevent this happening? try duct taping plastic over it? Is something like that possible?

I think that is 6 questions.

Cheers, JASON.

[MattW]

Pretty sure the O2 sensor is on the exhaust so duct tape not a good idea unless you like the smell of burning plastic

[Rodgebone]

there are two O2 sensors....one is upstream from the cat near the starter and the other is just aft of the cat next to the transfer case...id be suspect of the wire connectors as the units themselves appear very well sealed...try crc on those as well

if you want to reset the computer to the factory default setting disconnect the POSITIVE cable from the battery and touch it to the negative terminal for 30 seconds...turn the key on but do not start...turn the headlights on (to discharge the capacitors in the computer)...turn the lights off and then turn the key off....reconnect the positive cable....the computer is now reset...id suggest letting it idle for 15-20 minutes before driving it so the computer can relearn its idle strategy then drive it nice and neat (like nanna) for a day....the computer will continue to relearn and refine its parameters for the next 50 key cycles...it will also learn to adapt to your normal driving habits whether u drive like nanna or a hoon

[Barefoot]

Mine occasionally does the same thing,my 02 sensor is being replaced under warranty shortly so I'll see if it fixes it.

Replaced the sensor a month or so ago and haven't had the problem occur since.

[Locked Lizard]

there are two O2 sensors....one is upstream from the cat near the starter and the other is just aft of the cat next to the transfer case...id be suspect of the wire connectors as the units themselves appear very well sealed...try crc on those as well

if you want to reset the computer to the factory default setting disconnect the POSITIVE cable from the battery and touch it to the negative terminal for 30 seconds...reconnect it...turn the key on but do not start...turn the headlights on (to discharge the capacitors in the computer)...turn the lights off and then turn the key off....the computer is now reset...id suggest letting it idle for 15-20 minutes before driving it so the computer can relearn its idle strategy then drive it nice and neat (like nanna) for a day....the computer will continue to relearn and refine its parameters for the next 50 key cycles...it will also learn to adapt to your normal driving habits whether u drive like nanna or a hoon

I know where 1 is, I'll go looking for the other, thanks. See how that goes, if no luck I'll try to reset and drive as stated.

[Wallace]

dont reconnect the battery in the beginning where roger says :hammer: only after you have drained the capaciters with the headlights on.

But yeah, i find that resetting the computer every once and a long while helps with a few of the running problems i end up with (pinging and ticking and the like).

[Rodgebone]

dont reconnect the battery in the beginning where roger says only


oops, sorry....you are quite right Will....the caps need to discharge with the battery DISCONNECTED....thanks for catching that man! :%

[shannon]

Hey guys, my car is stalling as well. my speedo doesn't work while the car is cold but after about 30k the speedo will start to work and then the stalling goes away and she runs fine. the speedo will only start working if i come to stop and then take off again. checked the cogs, speedo conection, and dash conections can some one help??

[Jonny Jeep]

Disconnecting the battery for several minutes is enough to clear codes. If anyone wants to reset their adaptive memory here is the full explanation and the link to the original thread it's from.
Forced Flash

This very simple procedure will Erase the “Adaptive Memory” stored inside the TJ PCM and allow a new “Adaptive Memory” to be developed.

After performing this procedure the PCM will re-learn and store into Adaptive Memory your engines performance characteristics.

Please perform these steps exactly as they are written, in the order they are written. This will cause the adaptive memory in the PCM to be erased and cause the PCM to go into Fast Learn Mode adaptive mode.


* Disconnect the POSITIVE battery Terminal and touch it to ground for 30 seconds. (This is to discharge the PCM capacitors, which maintain the Adaptive Memory.
Reconnect the Battery Cable
Turn Ignition Switch to the “On” position but DO NOT start the engine
Turn Headlight “On”
Turn Headlights “Off”
Turn Ignition Key “Off”


The PCM Adaptive memory has now been flashed, or erased from the PCM.

When you start the engine it will be running off a set of pre-programmed tables that come with the PCM from the factory.

When you get the engine up to operating temperature the PCM will start to collect data for the “Adaptive Memory”.

The PCM will collect data for Adaptive Memory for the first 50 Warm-up Cycles.


Warm-up Cycle

A warm-up cycle happens when all of the following conditions exist.

Engine is running
A raise of 40F in engine temperature must occur ABOVE the engine temperature at start-up
Engine Coolant Temp must reach at least 160 F.


Once your engine has gone through 50 warm-up cycles in at least a 500-mile distance the PCM adaptive memory is set. It WILL NOT Change unless you flash it out and start all over again.

This procedure is vitally important for this installation as the install includes much larger fuel injectors and a lot more air being forced into the engine.

However I believe a lot of folks may find it useful on their own Jeeps.



That info is from the following jeepsunlimited thread (post 108 )
http://www.jeepsunlimited.com/forums/showthread.php?t=511089&page=6