Blaze9

This just started happening a few days ago out of the blue. When ever the RPM goes over 2k when in drive and then you come to a complete stop, the RPM drops to just below 500 (498 according to Torque (OBDII app) hooked up to the car). I'm not sure why this is happening, but when it does, the car shakes (originating from the engine) noticeably for less than a second.

I'm going to take it to my dealer soon, but does anyone know what may casue this issue? I don't want this to cause any damage to the car (if that's possible).

Thanks,

justnspace

iTrader: (1)

any work done underneath the hood recently?

Blaze9

Nope, nothing. I just got the oil changed (30k miles) less than a month ago. They did ask me to replace the engine/cabin filters, but I decline (going to do that myself). I haven't yet touched the engine filter yet, but I did purchase a K&N dropin and a generic cabin filter. Other than that, there was nothing done to the engine of the car recently.

It's a 2012 3.5L btw. Forgot to include that in the origina post.

justnspace

iTrader: (1)

so, you did in fact put in the K&N air filter?

Blaze9

No, I didn't put it in yet.

justnspace

iTrader: (1)

so, that rules out any intake problems.
hmmm.

Blaze9

I'm going to put that off until I bring the car in. I don't want them to say it was due to a "incorrectly installed engine filter" and void warranty repairs.

Mr Marco

Maybe your car is depressed. I don't know what part of the country you live in, but up here in the north we suffer from seasonal affective disorder or S.A.D. for short.
Maybe your car is/has SAD.
I would first start by taking out on a good long country drive. Those short commutes to and from work are hard on a car. What with all that stomping on the brakes and cutting in and out of traffic. Cars like to be driven through the twisties and they also like a smooth right foot. Then take it out for a good drink. Don't fill her with that cheap CostCo gas. Go to the 76 station and buy some 92-3 octaine at $4.89 a gallon. Splurge and get the touchless wash too. She'll get a nice massage at the end from Enrico & Philippe. Boy howdy, those guys really know how to treat a lady. Spend some quality time with her too...I would also take her out to the drive in. Nothing is better than spilling a few a kernels of pop-corn down under the seat and releasing a couple of butter farts into her ventilated and perferated leather. She'll love it!
And while we're on the subject of girls, tell your wife to keep her fucking hands off her!

justnspace

iTrader: (1)

^i also was going to suggest maybe a case of bad gas?

Mr Marco

Yep, low octaine in the SHO would do the same thing to me. I stopped lending my car out after I realized people were returning with a full tank of REGULaR GaS.

Blaze9

Haha, that was a lovely read. Thanks.
She goes up and down the east coast at least 4 times a year. (Just came back from NC to north NJ less than 3 weeks ago. The car's only 1.5 years old and she's got 30k miles already!) I love long rides down Interstate 95. And I'm the only one who drives this car, and I always fill up at the same place, (almost always, 9/10 times) and I always get 93 octane.

I don't think it's bad gas. I hope it's something that simple, but I doubt it. Sister has an IS350 and we both filled up together last week, her's isn't showing any issues.

Mr Marco

Hmm, that is odd then. take her in fo sho.

Blaze9

Haha, I like your signature!

silkysmooth_96

Probably the torque converter. If it isn't allowing the slippage between the transmission and engine that it's required to at a stop then it will drag down the RPM as you come to a stop, then eventually release the pressure.

Does it do this in neutral or park if you rev the engine and let it drop to idle?

I'd be interested to hear the solution once it's fixed!

Blaze9

Nope, in park and neutral it doesn't do that. Also, this morning it wasn't as bad as yesterday. Today it went lower than usual (around 500, 550) and it didn't shake as badly.

CerberusKy

iTrader: (1)

Could be a vacuum hose leak... had that on my old audi, and once I fixed it the car ran fine for almost a week before the next problem.

Blaze9

I had that happen to my Camry after I (on accident...) gunned it from a stop in the rain and the traction control took over and made the car shake. The hose got loose and the engine kept on stalling/doping RPMs. I haven't hit any large bumps or potholes in this car, and I haven't had traction control do that in a long time. I do go over abnormally high speedbumps every day due to my university's parking lot being full of them.

justnspace

iTrader: (1)

^thats what I was getting at with the air intake.

could it be possible if you opened the hood and physically check for anything that looks out of place?

03tLsNBP

iTrader: (9)

I noticed this same issue happening on my 2G within the last few weeks only. Curious to find out what it is, though I'm not under warranty so I probably wouldn't fix it.

Just a thought, does this have anything to do with the extreme temps we've been having in the northeast lately (<20 deg)? My car was running fine before it got this cold.

Blaze9

I'm in North NJ, and yesterday it was around 10F in the morning, and today it was about 18F... Crazy cold. That's what I thought as well in the beginning.

Blaze9

Started the car today at my college, and drove down the lot. No issues at all... Hit 2-3kRPM, went down and stopped, and RPM was super steady on the way down, lowest was around 600-700, no shaking, not even a limp.... I wonder what could have been the issue... Hmm...

Tonyware

It may be the good-old EGR valve passage Honda J engine problem. Gets filled up with carbs, most likely from bad gasoline. Fill up with some high octane gas from a busy gas station and throw some STP cleaner in the tank too (the silver bottle). Go out for a half hour + highway drive to clean things up. If you really want to do some serious work, unbolt the top of the intake manifold and clean up that EGR passage with some car spray cleaner (there is a bolt/unbolt sequence though, and that make things more complex if not mechanically inclined....

(check the engine coolant level too, just a guess)

Blaze9

I'll definitely drop a bottle of STP cleaner if you think it'll help. As for the manual cleaning, It doesn't seem too difficult (used to do all maintaince my self back when I was going to school, but now there's hardly any time). Just gotta wait for the weather to clear up and get warmer. Been cold/raining/snowing here the past few weeks.

All engine fluids seem to be at an adequate level. Just got the maintenance done a month ago, and I just checked the oil/coolant levels this morning (cold engine)

dvdpgb

Same exact problem. Dealer recall on the torque converter. They will run a software update and it fixes the problem more than half the time but sometimes the actual torque converter will have to be replaced.

Blaze9

They updated the firmware/software on my transmission (I think, I'll have to look at the statement), and it did solve a good bit of the RPM drop, but there are still some rare drops. Not nearly as frequent as before. I'll drop the car off again later next month. Thanks for that info.

Teddybear

Bumping this.
I've noticed this on my 2010 when it's really cold out.

OP, if you're still around, what ended up happening? Did you find out what the issue was?

csmeance

The problem is a simple one to fix!

The ECU has to relearn the idle any time after it looses power. In the cold the battery provides less current and can starve the ECU of power.

The service manual states that you have to idle the car for approx 15 minutes with ALL ACCESSORIES TURNED OFF (A/C, radio, heated seats, etc). The cooling fan should kick on and off twice. After this is done, the car has releaned it's idle speed.

My 2004 TL had a low/weak battery and was doing what you describe. The RPM's would drop near 400-500 at redlights esp when the A/C kicked on/off.

I got a new battery and did the idle relearn procedure and the problem was fixed!

Blaze9

Nope, it seems like during the next service they update the firmware of another piece of hardware and it solved it. I haven't had this happen since. I didn't do anything abnormal to the car at all.

Teddybear

Thanks! Would resetting the ECU with an OBDII scanner work?
I have a suspicion my battery is on the low side as well.

csmeance

If the battery is low, it'll starve the ECU of energy and will cause the issue to repeat. Get a new battery (google autozone/pepboys coupons and pick up in store for 40% off)

After you get the new battery do the idle relearn and you'll be good to go. Only HDS can reset the ECU for the idle relearn so I'd just unhook the battery for 30 minutes. Make sure you have the radio/navi security codes!

Teddybear

Thanks! i'll check the voltage this weekend when it warms up a bit.

naiju84

Hey there OP, was the issue ever resolved? I am in the same exact boat as you. Took it to the dealer several times and ofcourse they could not duplicate it. But got the TC updated and the rpm still surges at times when coming to a stop and also sometimes when the AC kicks in at a stop. I replaced the EGR valve and also poured a bottle of BGK fuel injector cleaner in there too. But it’s still there. I have inspected under the hood and haven’t seen any hoses broken or leaking. But if there was leak it would do it all the time. One other thing I noticed is that if the AC is on and you shift from neutral to Drive, the rpms go down. I have a 2014 TL Fwd with 26k miles.

justnspace

iTrader: (1)

idle surge is indicative of a vacuum leak.

Check the intake manifold...

A4D7

If using torque obd2 sometimes it can cause a rpm drop or shudder, try connecting to different protocols or getting a more reputable adapter to connect to. I had this problem in my subaru, it imitated a vaccum leak. Didn't have any problems with my 3g tl though. If you've checked everything else without any luck, drive without it for a week.

naiju84

I don’t have anything connected to it. But thanks for the reply.

naiju84

Hmmmm... I did not think of the intake manifold. Thank you for the suggestion.

justnspace

iTrader: (1)

^specifically the back of the intake mani, where all the vacuum hoses get hooked up

naiju84

Thank you ... will keep you guys posted!!!

wayver

Did you ever get to the bottom of this?

My car does something similar, where the revs will drop low and bounce up again. This tends to happen right when the car upshifts, but doesn't really need to / I take my foot off the gas at around the same time (when driving uphill through a parking lot and slowing down for speed bumps, or uphill and slowing down to turn of the road).

naiju84

Hey there
I did not get a chance yet to do so. Sorry!!!