Help! Rev limiter kicks in at 7300 RPM!

[paulviriyapan]

So I've had the car three weeks now. The problem is that the stupid rev limiter kicks in at 7300 RPM. From what I read that should be 8300 RPM; furthermore, the fun supposedly starts at 7000 RPM. Is there anything I should do or check to fix this? Is there any way that you can adjust the limiter settings yourself (without a computer set up)? Any help greatly appreciated. Thanks.

 

[Vytas]

You must have not let the engine warm up completely. The engine will not rev to 8000rpm if it's cold. You should drive the car normally until all the mechanicals get to operating temperature. The temp gauge should be a click or two below half. Then you'll be able to reach redline no problem.

 

[dgaetano]

If the engine is not warmed up the VTec will not engage. Without it the car loses about 1K rpm off the red line.

There was a nice thread on this a few months ago in the old forum, but I'm not certain how to find it now...

-Daniele

 

[NSX-Racer]

...also when too hot

The same can happen when the engine's too hot - I experienced that on Hockenheim short track after some laps after an Integra - limiter kicked in a bit under 7000. One more lap with free air solved the problem.

 

[nsxtasy]

I agree that it's possible the car is just cold. See where it cuts off when it's fully warmed up. If you can't rev to redline when warm, then there's a problem.

From what I read that should be 8300 RPM

The rev limiter kicks in at an indicated 8300 RPM, which corresponds to an actual 8000 RPM.

Originally posted by dgaetano
There was a nice thread on this a few months ago in the old forum, but I'm not certain how to find it now...

There was a post about the rev limiter and tach error on the newly-formed NSX e-mail list here. Those wishing to join the list can do so from its home page.

 

[BadCarma]

I wait a tad longer then water temp to come up,I wait for oil and tranny temp to warm to optimal before engaging v-tec or 8000. not that I have any facts that make it correct it is from some reading i've done that is generic to all high performance engines and am not sure of the validity but it is only a few minutes longer and cant hurt. Nsxtasy, your a wealth of info.does this have any merit?
david

 

[nsxtasy]

does this have any merit?

Yes, it makes sense to wait for everything to reach normal operating temperature before hard acceleration and revving to redline. But that's basically what the ECU is doing for you automatically, by lowering the rev limiter until it's all warmed up.

 

[supercharged]

This can also happen at the upper extreme; i.e. over-heating or oil starvation will cause this to happen to protect the engine.

 

[Soichiro]

>>The problem is that the stupid rev limiter kicks in at
The STUPID rev limiter? You mean the high-tech device that virtually no other car (except for top line racers) has and can save you from destroying your engine? Yeah, pretty stupid.

 

[Lud]

The ECU adjusts the rev limiter to keep you from damaging your engine when it is too hot, too cold, short of oil, etc. If your rev limiter is kicking in below 8000 RPM when the car IS warmed up, there is a problem with it. Take it to a qualified mechanic.

BadCarma's thinking is correct. Oil temp is key, and oil is not up to proper operating temperature/viscocity as fast as the water. Various metal parts should also be allowed to expand to their "worn in" operating tolerances, etc. The ECU retards redline based on water temperature. The water temp goes up well before the rest of the car is warmed up.

Water temp goes up within a matter of just a couple minutes (unless you have a faulty thermostat). If you start it cold, you should warm the car up for a good 15-20 minutes of easy dryving before you run it hard -- meaning either high RPM or heavy throttle.

While the ECU rev limiter is there to prevent you from outright damaging your engine, a little extra warm up can help you minimize wear and extend it's useful life.

 

[Lud]

The STUPID rev limiter? You mean the high-tech device that virtually no other car (except for top line racers) has

Most modern cars have a rev limiter.

 

[nsxtasy]

Most modern cars have a rev limiter.

Do most modern cars have a rev limiter clever enough to have a lower limit when the car is cold than when it's warmed up?

 

[Larry Bastanza]

Lud,

Totally agree. As an indicator of proper warn oil temp, I use the oil pressure gauge to insure I am idling at about 1 on the gauge.

Some cars are different so the absolute # may vary. Take your car out for a good drive, as Lud recommends 15-20 minutes, fully warn and check your oil pressure gauge at idle. You can use it as a reference.

When the oil pressure is there you are OK to have VTEC fun.

HTH,
LarryB

 

[Lud]

Larry's advice is good. The warm-up time also varies with ambient temperature.

nsxtasy - On modern engines that rev high it is pretty standard. Your ITR should do it too, though the specific RPM cutoff points probably differ. Engines with a low redline may not implement this feature because they don't rev high enough for it to be as critical.

 

[huckster]

hhmmm. My new s60 Volvo does not have a cold engine lower rev limit. It did have a lowered rev limit up until about 5k miles. I was really surprised when one day-BAM-the car started accelerating twice as fast and was higher revving. Do new nsx's also have a lowered 'break-in' rev limit??

 

[nsxtasy]

Do new nsx's also have a lowered 'break-in' rev limit??

No.

 

[paulviriyapan]

Okay, discovered a funny thing. I TURN OFF the TCS, and the engine revs to 8,000. Umm...is this normal, or should I be concerned? Is the TCS designed to keep the engine from revving that high, or is my car goofy? Thanks.

 

[nsxtasy]

Is the TCS designed to keep the engine from revving that high

No. The TCS operates only based on wheelspin, and has nothing to do with the rev limiter. However, it's possible that you are encountering wheelspin (particularly at higher revs) and that this is causing the TCS to kick in.

The most common causes for the TCS to kick in are (a) use of tires in sizes other than the stock sizes; (b) lack of smoothness with throttle (accelerator) inputs; (c) use of tires that are not very grippy. Especially (a). What size and model are your tires?

 

[paulviriyapan]

Factory '91 wheels and tires, 16" in front and 17" in back. With the TCS on I can't hit 8k. But when I turn it off, I can hit no problems. What could be wrong?

 

[paulviriyapan]

Incidentally, the PO installed the COMPTECH chip in there, so I don't know how and if this would affect the Rev limiter.

 

[nsxtasy]

Factory '91 wheels and tires, 16" in front and 17" in back.

The factory '91 wheels are 15" in front and 16" in back.

However, if you have tires in the OEM sizes for '94-01 (215/45-16 front, 245/40-17 rear), that should NOT set off the TCS.

You might want to call Comptech and ask them if their chip can lower the rev limiter.