2003+ Idle Relearn Procedure for 3.8L Montero

[haolepinoy]

Does anybody have or know where I can find the correct idle relearn procedure for a 2003+ 3.8L Montero? I've been looking through my Factory Service Manual and can't find it mentioned. I've found a few TSBs online but they are for overseas models (GDI and Diesel variants)...and they're all different so I don't think the same procedure will work on mine (well, I know it doesn't because I've tried them to no avail).

Thanks.

 

[nckwltn]

disconnect the battery for about 20 minutes

 

[haolepinoy]

I know how to make it forget.

Trying to help it RELEARN a proper idle the right way rather than the hard way (which is me sitting in traffic with the ac on stalling out constantly because it hasn't yet figured out that 450 rpm ain't gonna cut it).

 

[loremordred]

I'd clean your throttle body, air intake, and it should help.


It helped mine when that was happening to me. Also check battery power/alternator/fuses.
Sent from my LG-H901 using Tapatalk

 

[nckwltn]

Haha. I'm reading you now. The only way I know is to drive it around. But cleaning my throttle body and air maf sensor helped with idle in the past... not so much that it just worked, buy better than 450..... maybe like to 600

 

[haolepinoy]

Sorry I haven't said thank you for the replies. Life has been a little overwhelming and honestly haven't had time to mess with this issue much. I did remove the throttle body and clean it up (it wasn't that bad)...did the EGR valve too for kicks and giggles. I'm wary of cleaning the MAF since it's a Karmen Vortex version. Everything I've read about them tells me DO NOT CLEAN THEM EVER OR YOU WILL RUIN THEM...plus it's not very dirty anyways. Throttle body gasket was in decent shape, though it is an aftermarket Fel-pro version (doesn't have the metal impregnated in the gasket material like the OEM or the Victor Reinz). Not sure if that makes a difference, though the FSM did say that a bad gasket would cause poor idle. I think I'll buy a new one (correct one) for next time.

After getting everything hooked back up I idled the truck for a while (10 mins), no ac or accessories. Idled properly at 700 rpm, but at some point it began to play with things...almost as if it were adjusting itself. I wish I had taken better notes, but it wasn't random ups and downs, more like it was trying different trims and adjusting itself. Shut engine off for a few minutes and started it again, this time idling with the ac on...engine idle would bump up like the FSM indicates, but the voltage would drop (I have a plug in digital voltage gauge that I keep plugged into the center console 12v outlet). It is this "drop" that I think is causing my stalls, because I'm not getting enough spark to run.

I've had my eye on the alternator for a while since it doesn't seem to keep up with demand, but am a little gun shy on pulling the trigger to buy a new one since I'm not sure if it's the, or the only, culprit (see my other "slaying electrical gremlins" thread...which I need to update as well). A question that I can't yet figure out is who controls the alternator's voltage output? Is it the internal voltage regulator (which, well, regulates the voltage) or is it the PCM (which tells the regulator to regulate based on demands, etc.)?

I'm hoping to fix some wiring gremlins this week (hard to find time) including: new battery terminals, cutting back corroded positive and negative cables to crimp on new ring terminals, checking the alternator "B" terminal side of the positive cable (including voltage drop tests, et.al.), refinishing all engine compartment grounds, etc. I may even remove the alternator to clean it (pretty sure it's covered in oil like everything else under the hood). Hoping to make something better and rule out any "other" issues. Then we'll try the new alternator step if needed (they're really not that expensive...compared to a PCM ).

Again, thanks guys for the advice...still wish I could find the TSB for the relearn procedure though. If it exists, and I find it, I'll be sure to put it up here for all future owner's reference.

P.S.: I really despise the previous owner and his lackey mechanics because it seems like everything under the hood has been over-torqued in the past...so many stripped threads particularly if the part is aluminum. I'm longing for the day when I can find a 3rd Gen in a junkyard because I've got a list a mile long of small parts I need to replace. Anybody in Virginia that sees one, please let me know.

 

[Salonika]

Read up on doing voltage drop tests, they are very useful for diagnosing alternator issues. All you need is some long test wires with alligator clips and a volt meter.

 

[haolepinoy]

Read up on doing voltage drop tests, they are very useful for diagnosing alternator issues. All you need is some long test wires with alligator clips and a volt meter.

10-4 on that one. Found the three different procedures in the FSM and picked up a test light plus my Fluke. Hoping to start probing around soon.

 

[mbialick]

I just had my timing belt, water pump, and cam seals changed at a shop. After picking my montero 3.8l back up the idle drops so low it’s about to stall when I come to a stop. I took it back to the shop and he did a re-learn procedure. The car ran great and idled perfect. On my drive home later that day idle dropped back down again to almost stall at stop. Anyone deal with this? I’m reading it could take weeks for it to fully adjust or could be a dirty throttle body and relearn took it back to oem settings.
Idle was perfect before the service and immediately after the relearn.
Frustrations high!

 

[coffeegoat]

It could still be learning or it could a dirty throttle body. It took mine roughly a week to figure itself out, running AC at idle was particularly challenging early on. Cleaning the throttle body is pretty easy, depending on how good of a job you do it only takes about 10 minutes, search around for a full procedure but every time I change the oil I usually do a quick version. My procedure is to warm up the truck and then have someone hold the throttle at ~2000 RPM, spray in cleaner for 30-60 seconds at a rate that doesn't kill the engine, and then increase the spray to kill the engine. Let is sit for 10 minutes, fire it back up and hold it at 2000 RPM until the smoke clears. It's not as thorough as you can/should do with a really dirty unit, but it keeps things tidy.

 

[haolepinoy]

The re-learn procedure is located on page 6-26 of the owner's manual under the heading "What to do if the engine speed becomes unstable after the battery is replaced."

Everything idle-related on the 6G75 engine is logic-based, relying on sensor inputs and outputs to regulate engine rpm. It will tune itself based on several drive cycles. The relearn that your shop did was probably just a battery disconnect, which reverts the PCM back to a baseline tune. That's likely why it idled well when you picked it up at the shop, but after driving it a bit (with the PCM tuning itself during the subsequent drive cycles) the idle dipped again.

Try the Owner's Manual method and actually sit and watch the tachometer during the 10 minute period. You'll actually see it hop around, testing itself at different engine speeds. When the hunting around stops that means it has learned enough.