Engine RPM problem
 

I originally posted this on another acura forum but did not receive that many suggestions or answers. Let me know what you guys/gals think


This is my first post so hopefully the information I wrote down will makes sense.

I joined this forum just to post this; since we are all TSX owners I thought everyone would benefit from this.

Sorry about the short form but it’s to much to type.

I have a 2009 Acura TSX with about 11,000 kms.

Brought in my car to an Acura dealership with break problems because it was squealing. Thought it was due to the recall but the service guy said it wasn’t. I still have over 80% on my breaks. He said maybe it’s the breakdust but it’s not due to the recall so they did not replace the breaks. They did however take it apart and cleaned off the break dust. Didn’t have to pay anything, warranty covered. (my breaks are still squaling, pissing me off)

Anyways that’s not the problem
So a couple of weeks ago before I went to the dealership, I was driving on the highway, figure what the heck I’ll give my car a good boot.

Changed to “sports mode” and played with the tiptronic. Floored 2nd gear then changed to 3rd gear, still flooring the car on 3rd gear, once I reached 4000rpm I noticed the RPM needle drop a little bit and the engine hesitated for about a second, after that second it went back to normal. After seeing that, I tried it for about 3 other times and everytime when I hit 4000 RPM on 3rd gear (flooring it) the needle and engine hesitated.

When I brought in my car for service I told them about my breaks squealing and also the engine problem.
Went out with the technician for a road test and duplicated the same engine problem. He said that he has never seen that before and has no idea what the problem is. He will call Acura Canada to see if they know of any other know cases.

Got a call back today from the service department, there is no answer yet but they tested out another TSX and they had the same problem. They informed Acura Canada that it is not just my car and I am waiting for an update.

Since this is not just my car now, I was wondering if you guys have the same problem?
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This is not a problem, this is VTEC changing its camshaft profile:

http://en.wikipedia.org/wiki/VTEC

And yes, it happens on my car as well.

Have the same problem, I hate it:ugh:, almost the only thing I dont like on my car. You dont have the problem when you drive it on automat instead the sort mode with paddle shifter?

Is the VTEC engagement point/RPM really that low (4k) on the 2nd gen? In the 1st gen, it's at 6k (or 4850 RPM for those with Hondata).

When my VTEC engages, the RPMs shoot up (not dip down), and there is no hesitation. If my sister's home later today, I'll play around with her 2g TSX to see her VTEC engagement point and behavior.

By "engagement point", do you mean the moment when VTEC engages behind the scenes, or the moment when the driver feels it? I think we might be referring to two different things.

Here's something I found on Acura.com, which seems to be exactly what's happening here:

Intelligent Variable Timing and lift Control (i-VTEC®) increases horsepower by advancing valve timing relative to engine rpm. High-rpm airflow is enhanced by opening intake valves longer and deeper at approximately 4500 rpm.

on 2nd gen TSX's, VTEC kicks in at 5k...YO!

hmmmmm i'm pretty sure it's not the Vtec, i had a 2000 honda civic SI before and that never happened. Plus vtec is suppose to kick in and propel the car not make the engine lag or rev down.

I have this update as well from the other forum, forgot to post it

Ok so Acura call me back.

They did a couple of test at their head office in Canada.
They found the same problem with the cars they test drove in Toronto.
The head office thinks that it is a “torque regulator” problem but they are not 100% certain.
They are now going to take a “snap shot” of the problem and analyze it.
Will call me back with an update in a couple of weeks.

I wonder if they are going to do a recall for this problem since it has been confirmed from numerous test drives?

second comment

Got a voicemail back from one of the service tech guys.
basically this is what he said.

They ran more test on multiple 09 tsx and found out that it's the torque converter kick in.
They do not know if this is a problem or a normal characteristic (wtf?).
They haven’t had any complains about it and will monitor the situation.

This is what he suggested
“maybe it’s my driving habits, this only happens on higher rpm, I could regulate how high my rpms are when I drive”.
They will contact me if there is any future updates.

So this is pretty much BS, I haven’t called him back yet with a response.

From the sounds of it, they won’t do anything about unless there is more peeps that complains.

Wow, thanks for the leg work. I stand corrected.

Well we can all still PRETEND Like it's VTEC kicking in....yo.

its definitely vtec yo

I checked this out on my drive home tonight and noticed the RPM drop at 4K.

If you check out the torque curve on the dyno plot, it might explain why.

http://www.vtec.net/articles/article.../09TSX_6MT.gif
http://www.vtec.net/articles/article.../09TSX_6MT.gif

Ive felt the dip between 3100-3500 RPM but never really felt the dip at 4000 since the duration was fairly short. Note, this plot was on a MT so there is no torque converter. I also have an AT. Now if you mix in what Acura told you with the torque converter locking up at 4K, it would kind of make sense to see a dip in RPM.

There's already a slight drop in engine torque which we know has nothing to do with AT since the plot is of a MT. If you add the additional load of locking up the torque converter, you should experience a drop in RPM. The reason why torque converters lock up is to get better fuel economy when traveling at highway speeds (3rd gear @ 4000rpm is around 50-60 mph).

Lets say you're riding a bike with the rear wheel off the ground and you're pedaling at a good pace. Next the bike drops down and the tire hits the ground. You now have an additional load to power. You cant instantly compensate for the additional load so your pedaling slows down, but you put down more power to get back up to speed. Same thing is happening in the torque converter. Below the lockup rpm, the torque converter is constantly slipping. At the lock up point, the engine and transmission are locked up so they spin at the same speed which means the engine see's full load from the drivetrain instead of letting it slip in the torque converter. Think of the lock up point as the moment the rear tire of the bike you were pedaling hits the ground.

I bet Acura/Honda will say its normal. With the dyno plot and the data of the torque converter lockup, I wouldn't be worried and just consider it a quirk of the car.

Sorry for the engineering babble, hope you guys can see whats going on though.

thunderbt3, thanks for the explanation. I googled some more info regarding torque converters and lockups and found that we're not the only ones experiencing this RPM dip. Many other AT cars, including BMWs, encounter the same issue.

Now I know why some people prefer MT over AT. Not because of the RPM dip, but because of the fundamental difference between how the transmission is attached to the engine, the fluid vs. mechanical difference. Fascinating stuff for sure.

sweet, good answers!!
Thanks thunderbt3 and mrotocinclus for the info. This forum is waaaaay better then the one i joined b4, glad i joined this one.

M/T for me, no problems at all :)

Thanks for the explanation! As far as the breaks, same issue here. They are claiming its break dust but it didnt help when they cleaned them off. Im instructing them to replace the brakes per the settlement when i go in tomorrow.

BREAK: when you snap a twig or drop a glass

BRAKE: That thing that stops the car (there's 4 of them)

Boy sometimes a manual trans car is a pain, but every time I've had one, it had less quirks and problems than the auto trans versions.

The proper term is "four" not "4" unless you are talking about age or money. A numerical digit that is under two syllables should always be written out.

seriously simba did you really have to correct him for making a typo? i believe we all understood which version of "Brake" he was talking about. its no fun being a grammar cop man

I have the same issue and I've had it on my 06 auto RSX also. Its because of the auto tranny and gearing setup. It just drops out of the power band. I'm sure a 6spd auto would fix it.

This happens for me when I'm in the "s" mode with my AT. When I am in 5th gear and drop it down to 4th for a quick boost or to pass someone it will dip down and then come back up. Thank you to those who already did the leg work on this issue. It bother the chit out of me.

Any updates on this problem? I had my 09 in at the dealer last week to look at this and the tech was stumped, had never heard of it before, and was going to "make some calls".

Any chance Acura has an update to the software/ECU or something that will fix this? Having a noticeable hesitation in the sweet spot of the RPM range is really disappointing.

torque converter lock up?
https://acurazine.com/forums/showthr...ghlight=torque

Thank you for explaining the Torque Conv. lock up. But in my case, I don't see the issue to be the converter since driving in full auto (d-mode) there isn't any problem accelerating. If TC Lock up is the issue, the problem should be consistent whether you accelerate on D-mode, S-Mode or S-Mode Manual. also on D-mode coming from a steady pace and will try to pass, a hard press on the gas pedal will initiate a downshift and rpm shoots up. Meanwhile, with the issue I am having, driving on either D-Mode and S-mode, when I flick the negative (-) paddle to initiate a downshift on a same scenario, the RPM drops and i can feel a loss of power pretty much like a fuel cutoff. the engine pretty much stalls for a moment and then strangely come back to life. it's not even close to the bike example. totally different. I do understand the physics working behind the bike example and it's not the case on here.
I can explain explain where the bike example applies.
When accelerating and you flick the Positive paddle let's say at exactly 6000rpm, the RPM shoots up a bit to 6300rpm (that is the rear wheel of the bike coming of the ground.. your pedalling became a lil bit faster because suddenly there was no friction between the tire and the ground) and once it shifted to a gear the RPM drops (but does not continuously drop and lose power) not just because it moved to a higher gear but because there was friction again. Now that is normal... what isnt normal is that when you shift up.. the RPM, after jumping slightly up.. drops significantly and any gas pedal activity does nothing... it's like it went dead for a moment then it wakes up again.

6MT...................

*grin*

Thank you. That helped a ton

Geeeeeeez.