madmanmax3000

Just wanted to chime in as another 16 year old who got the TSX as a first car. I looked at every car imaginable in the 30-35k range (G35, Altima SE-R, 325i, C230, Accord Coupe, IS300, and even an R32!) and am so happy with my decision. For this price, there is really no better car IMO. My only concern is that I may have become a mod addict.

sauceman

sauceman, who is also curious to know...

Saintor

It is not because of the tranny that the engine shakes at idle under load - obviously..

jcg878

Nope, can't think of a soul

dom

fdl?

05_TSX_GP

What is meant by engine shakes at idle under load (on AT)? Do you mean the RPM varies (hovers around 800rpm)? If that's what you mean, I think that's just because more electric current is being drawn (cooling fan, a/c, etc.) while idling, thus engine kicks up a bit to compensate. I've seen that on even MT cars, any car really.

Saintor

Nothing to do. Engines fight against brakes, thus is under load. You can recreate this with a manual. Brakes on, release the clutch and rev a bit to whatever engine speed an automatic revs at stop on D. My Accord 4 cyl. was terrrible in this aspect.

ClutchPerformer

But with an MT, the engine is NOT under load at idle. SO THE TRANNY HAS SOMETHING TO DO WITH IT.

CGTSX2004

iTrader: (1)

And you're honestly telling me that a BMW doesn't do this?

Saintor

Exactly (I6 only). Certainly not at the same level of your typical I4.

05_TSX_GP

That still does NOT make a single bit of sense to me.

First off, whatever steps you listed most certainly do not recreate a scenario of an AT - because AT does not have a clutch. AT and MT boxes are just completely different mechanical devices. They both have same function but internals are way too different for any "experiment" to be conducted on MT to be claimed to be recreating an AT situation.

Secondly, according to your steps on the MT, it invovles "rev a bit", that means the engine is NOT at idle anymore!

05_TSX_GP

Just realized there's a third point that your assertion troubles me... which is - now you've put the brakes into the equation too!! So maybe the brakes were making the engine unsmooth on your Accord I4?

Oh no, a forth point just came to mind now... doesn't the engine on AT also rev around 800rpm at stop on D? That's also the usual idle rpm when an MT car is in idle.

oh, ever try your experiment on an AT by doing stop and put it to N? That would take the tranny and brakes out of the equation.

drchaos

Alright guys, time for some engineering 101.

What the problem is (e.g. 'lugging') is when the throttle is closed so that the air flowing into
the engine is not very high, and thus the the power that it can put out is fairly low, *and* you
induce an extra load on the engine, meaning extra mechanical work that it has to do. Engines
can only put out a certain power at certain speeds, and the extra load causes the RPMs to get
too low. Since an engine is an air pump, that also means that the amount of air that it sucks in
is lower, and hence with less air per unit time, the less power it can make.

The difference between AT and MT consists only of what kind of load you put on the engine, but either way
the response of the engine doesn't matter.

In a MT, when you are in gear, but with the clutch pedal pressed in, then everything is fine
since the engine only spins one side of the clutch freely. When you start to let up the clutch
pedal (that's "engaging" the clutch) then you start to get some friction between it and the other plate.
If your foot is on the brake (and brakes are much more powerful than engines), then the wheels
don't move, and so the driveshaft doesn't move, and connected back through the MT, the receiving
plate can't move, and thus you get one disc turning, touching another disc which is stationary,
and so you get friction (and burning up your clutch) and this is a load on the engine, resulting in low RPMS.

In an AT, there is not a primary clutch (though there are in fact 'clutches' in the AT body itself to switch
gears), there is a 'torque converter' which is a fluid coupling. Think of one turbofan turning fluid which then turns another turbo fan. It is possible for the receiving turbofan to be stationary and the other one turning and moving fluid around (there are really 3 fans but that's just a detail).
I.e. since the flow is a fluid and not a solid disc, you can have more slippage allowed. That's why you can keep your AT in gear with your foot on the brake at a stoplight.

However, the engine still has to turn the input propellor and there is still a pump operating the fluid in the torque converter. You are spinning fluid which hits the stationary receiving fan, and this causes fluid friction, and also a load on the engine. When you shift an AT into neutral there is either some disengagement
of the engine shaft from the input of the torque converter, or some stopage of the pump in the torque converter itself, so that it isn't turning the fluid inside at all or if it is there isn't as much friction between the
various turbofans. Thus with less load, the engine RPMs go up until it reaches a new, smoother equilibrium, i.e. happy idle.

Being unsmooth is simply a property of putting too much load on an engine when there is not enough air to give it more power to make up for the load.

05_TSX_GP

Thanks for the detailed refresher lesson

From this definition (I think it's a good one) then, the tranny (especially since the original complaint was an I4 on an AT being unsmooth at stop in D) and its "helper" components have LOTS to do with that "unsmooth" observation then.

drchaos

Yes. There can be a number of reasons for a bad idle in D in an AT.

Firstly, the engine can be not in as good tune as it should be, spark plugs, plug wires, clogged fuel
injectors, misadjusted mass-air meter, bad EGR valve, etc.... And if it is borderline out of tune, then
when you put it in a more loaded situation, e.g. autotrans in 'D', then the problem is more obvious.

That's a case when the problem is in the engine and the AT is working fine but is only making the engine problem more clear.

It can be otherwise, however. Modern cars (e.g. late 80's to now) try to do various things to improve fuel consumption. In city driving it turns out that you spend a fair amount of fuel at idle, and so it's good to minimize that. What they then do is to make the idle lower (i.e. less air and hence less fuel), but under
load from an AT in Drive, it would be too rough. So they have all sorts of automatic servos and
control mechanisms to deactivate the torque converter when stopped in 'D', either mechanically or
in fluid side, and then immediately reactivate it when you start to accelerate. That's probably computer controlled now and something that is supposed to be unnoticable. If there is a problem in this system,
electronic or hydraulic, it may be that the AT's torque converter is not disengaged the way it is supposed to be at 'D', and the engine is actually fine.

PWTSX

hmm all good cars.

TSX has the best value.

gatrhumpy

iTrader: (1)

Why did you bring to life all these old threads?!

Sclass88

These threads are so old. Quit reviving old threads that don't really have merit any longer.

majin ssj eric

^^Nostalgia???

jdepasqu2

A assume you are talking about Piazza Acura of Ardmore......, I just got an 07' NHBP 6sp. with navi from there for only $27,000......, and they treated me really well also......., They do seem like a good place to deal with.....