DuckDodgers

Amusing little experience today (and I searched but could not find another reference).

Stopped at a light, in neutral, off the clutch. I wanted to rev it a bit because I had added a fuel system cleaner and wanted to work it through the revs a few times, hoping to help the cleaner out...

...what should happen, but the engine hits a rev limit at 4500! WTF, I thought perhaps the gas was bad, but taking off, it ran smoothly up to redline. Took a moment on a quiet commercial street to fiddle with it, and the limit is only there when your wheels are not rotating.

Any experiences or knowledge?

S14 n Tsx

never had that experience before.. sorry that I couldn't help.

savage

it so you don't blow you engine... you shouldn't be revving that high when there is no load on the engine...

PACman

Yea, when not under load (in neutral), the rev limit is 4500rpm.

JTso

iTrader: (2)

it's by design. AT is 5000 and the limit is lower if not warmed up.

Benz_05_TSX

iTrader: (1)

^ I have AT and went up all the way to 5k!

fadinglionhart

maybe AT's still have the load of the torque converter to spin up?

DuckDodgers

OK...why? Now, I'm not suggesting that it's a good practice, but I doubt the engine would blow from just that...(but I'm not an engineer...)

My understanding of the difference between reving to 7000+ under load (in gear) and not under load (in neutral) is that the acceleration of the engine would be faster with no load...but it seems mechanically unlikely (if not plain impossible) that one condition would shread the engine where the other just lets you accelerate well. Now, if the arguement was about a lack of cooling air flow, we can talk.

One thought of "concern" was that to get a fast 0-60 time it is sometimes necessary to rev the car up to a high rpm and dump the clutch (I do not know what the accepted practice is for maximizing your acceleration in a TSX, so I'm NOT suggesting doing this)...so if a gear is selected, but the clutch is not released, is it still a 4500 limiter? What is the switch...neutral position switch, ABS sensors not in motion, etc? I also wonder why this isn't referenced in the OM or the SM (that I could find).

A Cake On

Rev limiters on a naturally aspirated car are a good thing. Not so much on a car with forced induction though. But thats besides the point. Be glad that it's there, cause if your motor is up at 7000 rpm and somthing goes wrong it's going to be big.

DuckDodgers

Agreed...if it doesn't big brother me at a stand-still! This is pissing me off...anyone got Honda's reasoning?

jlukja

^^ Honda thinks the TSX is not a race car and can't think of a reason why you would want to?

savage

I should have probably said that better, i doubt it would blow your engine if you did it a couple times but over time it think it would wear down the engine and lead to problems. Someone had explained it once, I can't find the post, but the engine is designed to support some minimum load which should be present during those high rpm's to help balance the internals.

I am not sure what the switch is on the TSX, it is probably the car's ecu which should know the speed of the vehicle for VSA and such. Reving up and dropping the clutch is good for launch times, but you can also over-rev on a launch and lose traction. I think Hondata may raise that rev-limiter slightly but i don't think it would remove it.

some related links...

https://acurazine.com/forums/showthread.php?t=33728
https://acurazine.com/forums/showthread.php?t=14085

JTso

iTrader: (2)

Dumping the clutch won't increase the acceleration when the wheels are hopping. I believe VSS (vechicle speed sensor) is responsible for detecting movement of the car and limits the rpm. The fuel cut-off info is in the service manual under Fuel & Emissions section.

DuckDodgers

Thanks for the feedback. I'm not looking to race the TSX, and I don't do tire squealing launches anyway. I just don't like a nanny that I haven't been told about and that I can't disable if I wish.

I know ABS falls in this category...and yes, I'd like to be able to turn it off (but I know why we can't...lawsuits. Of course, if you hit someone on gravel you can sue the manufacturer for not providing an off switch as it is proven that locking the tires on gravel reduces your stopping distance). I'm just opposed to dumbing down your control options on a vehicle because the population, in general, is too stupid to be trusted with such control.

Zoopa

The current BMW M3 has the same feature. Apparently a lot of people were revving the engine, with no load on it, and destroying the head. German engineering...

savage

the M3 had a bad bearing... that is why so many we blowing their engines... i remember hearing about a couple people who blew their engines while just cruisin on the highway, not reving hard...

http://yoy.com/yoy/auto/m3_failwhat.shtml
http://members.roadfly.org/jason/m3engines.htm


also the M3 has a real launch mode with SMG. The new M5 and M6 also have this. Basically you press the brake, step on the throttle and it will launch at the optimum RPM each time... They also supposedly have an easter egg mode which lets you launch them even higher, but i think after a limited amount of those launches your warranty on the power train expires. Something about how each of those launches eating up clutch...

aaronng

Revving with no load at full throttle causes a high rate of RPM increase, which is bad for your engine. If you were to rev it up to 7000rpm in neutral at the same rate as you would in 1st gear, it won't be as bad.