2006 MT ~90k miles

I was on an 800+ mile road trip (August in the midwest), cruising at 80 mph, and upon pulling into a rest area, my idle started fluctuating. It would go down, and then back up again. When it went up, it would go into the 1000s, slightly overshooting the normal idle speed. It never died. It just bounced.

I've never noticed anything like this before, and it doesn't do it now that I'm back home. But I have seen it do it a couple times after that first time. I thought about Seafoaming. I found in a search that if you disconnect a battery cable, the computer does an idle relearn? How does that work? Do you really have to let it sit there for 15 minutes idling? That seems odd to me. What if the battery cable is disconnected and the car is never allowed to idle for 15 minutes? What happens then? How do you know the procedure is completed or successful?

Haven't done a tuneup yet. No other symptoms. If I start driving, power is not interrupted. Cold starts are fine. No check engine light.

Thanks in advance.

 

This is not totally uncommon with an engine that has been running under these conditions on a hot day. The internals get quite hot and the fuel can vaporize quickly as it is drawn into the engine, thereby causing a few cylinders to starve slightly until things cool a little and/or stabilize. For what it's worth, you should never turn off at a rest stop or gas station after having run at highway speeds for a while and turn off you engine right away. You should let it idle for a minute before shutting it down. Of course, if the rest stop or fill up means you need to drive a couple of minutes a low speeds, then you don't need to do this.

Another cause of this can be fuel that your engine doesn't seem to like as well as other fuels (my '04 manual TL doesn't run as well on Shell as it does on Amoco, which is BP). As for using SeaFoam, if you don't normally use a fuel system cleaner, then yes.. do this.

 

90k miles!!!
its ready for seafoam in the gas- 1 can to 1/2 tank, and vac port at TB- most of 1 can- `deep creep` aerosol seafoam is much easier to use there

AND its ready for new NGK Iridium spark plugs- accept no subsitutes- no kidding!
acura says they last to the 105 service-- but-- there are several things that wear them out early, like driving on Earth
Many ziners are replacing them at 60-70 and getting 1+ mpg increase~

top teir gas = tier 1 grade gas, is appreciated by the TL
especially type S with its higher 11 to 1 compression ratio
76 recently posted signs advising they are tier 1, that customers using T1 spend less time at the gas station... reading signs!! lol

tier 1 has more-`up to twice the min. amount the govt requires` of cleaners- so it cleans byproduct residue much better
E10 gas sucks for combustion cleanliness

plenty of youtube vids on `intake cleaning` with boroscope camera- the carbon layer crud on valves and pistons is unreal,,,goes away with proper cleaning and restores like new running

 

Thanks for the tips. When should the spark plug wires be replaced? Can I wait until the computer tells me to change the timing belt?

Should I take it to an Acura dealer for the valve adjustment? There's a shop in town called JH Car Care (just Hondas). I wonder if they're more experienced. Some time down the road I'll need new syncros. Is the entire gearset replaced at that time? I don't think the Acura dealer here has ever done a 6MT, and that makes me uneasy about taking it there.

 

TL does not use plug wires.

I would do nothing in the immediate future until you run another tank or two of gas through there to rule out a bad batch of gas.

After that I would start by checking the throttlebody and cleaning if necessary. Some people have issues with this but mine is extremely clean on both sides and I've never cleaned it.

Then there's the DBW, EGR, blown headgasket, etc.

What grade of fuel have you been using?