Rev limiter at 7400?

[vtecNSX1]

I posted this when i first got my car but it was never resolved. No matter how warm the car gets it will never let it rev over 7400 rpms. I have checked the vin and it was not originally an automatic. Does anybody have an idea of what could be causing this? I checked the faq and all it says is that the car must not have warmed up yet. Here is a link to the original thread from http://www.nsxprime.com/forums/showthread.php?t=23061 Thanks in advance

 

[DutchBlackNsx]

Couple of things to check:
- Did you pull the engine codes
- Does Vtec come in
- You checked the partnumber on the ECU to see if it is not an automatic ECU
- Is it clearly the rev limiter, or is it just holding revs
- Try to turn TCS off

You got any other failures on your car, speedo, temp, rev, tcs check engine light?


Mich

 

[EIFFEL]

Does the check engine light comes on when you first turn the key to on position? and turns off when car starts. If the check engine light never comes on, you may have a code stored. when mil is on, you won't be able to rev to 8k.

 

[DocL]

It could also be a problem with the VSS (Vehicle Speed Sensor).

 

[vtecNSX1]

Couple of things to check:
- Did you pull the engine codes
- Does Vtec come in
- You checked the partnumber on the ECU to see if it is not an automatic ECU
- Is it clearly the rev limiter, or is it just holding revs
- Try to turn TCS off

You got any other failures on your car, speedo, temp, rev, tcs check engine light?


Mich

I havent pulled codes i dotn know how.
Yes vtec does come in.
No i havent checked the ecu to see if it is automatic.
its definitely the rev limiter.
i havent tried it with the tcs off.
There are no other problems that i know of, everything else works great.

ya i think the check engine light comes on for a sec until i start the car.

 

[vtecNSX1]

ok i just checked it with the tcs off and it still does it. The check engine light comes on in the on position before i start it but turns off. How can i check the ecu?

 

[nsxtasy]

ok i just checked it with the tcs off and it still does it. The check engine light comes on in the on position before i start it but turns off. How can i check the ecu?

I'm just guessing here, but... swap it with another one known to be good?

 

[DanO]

I’d be surprised if it were a TCS problem. As nsxtasy said above, you can swap the TCS computer with a known good one and try it but you might just try disconnecting your TCS harness at the TCS computer box (located behind the driver’s seat). Many of us run just fine without the TCS computer hooked up. I think if you were having a sensor issue then the TCS light would be on and if it were a temp sensor issue then your gauge would not be reading correctly.

You might want to try swapping with a known good ECU box to see if this cures the problem.

Good luck!

DanO

 

[Briank]

I have some questions for vtecNSX1 about this problem.

Is the rev limit hard or is it just like running out of power.

Is your Idle speed within spec's.

Have you had any work done on the car recently.

 

[vtecNSX1]

nothing has been done to the car recently. It is definitely the rev limiter. the idle speed is fine i think.

 

[Briank]

nothing has been done to the car recently. It is definitely the rev limiter. the idle speed is fine i think.

Idle speed should be 800 +-50, what your idle RPM?

 

[vtecNSX1]

i think my idle is somewhat lower than that, maybe around 500.

 

[DutchBlackNsx]

At this stage you should:

- Verify ECU partnumber, also check for 'used' screws on the ECU cover, or write it down, and post it here.
- Pull engine codes
- Clear ECU memory (pull clock fuse for a few minutes)
- Go out and drive, hit rev-limmiter a few times
- Pull engine codes again

Pulling the engine codes is in detail discribed in the service manual which you can download here . Please check the section 'Fuel and emmisions'.

To make sure, please discribe the rev-limmiter, just to be sure. Different cars have different rev-limmiters.

If you don't feel confident with the manual out on your lap pulling screws and bits off the interiour off, see a dealer


Mich

 

[nsxtasy]

Swapping the ECU with someone else's is relatively easy. It's located on the wall behind the passenger seat. It screws out and has a big connector plug.

 

[vtecNSX1]

ive decided to get a new ecu anyways so well see if that helps. I just havent decided between the SOS supertune or the Dali super hot chip, but thats another thread.

 

[vtecNSX1]

O and i can tell its the rev limiter cause it kinda bounces off it. i dont know how else to describe it.

 

[Taj]

Could your tachometer reading is wrong and the actual rpm is over 8000? Check your tachometer reading and compare it with an external unit.

 

[Briank]

Could your tachometer reading is wrong and the actual rpm is over 8000? Check your tachometer reading and compare it with an external unit.

Taj might be on to something, a 500 rpm idle is very low and would cause CEL's so if you are reading low at idle it's possible you are reading low at the high end also.

 

[sutphen77]

I have the same problem between 7000 and 8000

 

[vtecNSX1]

actually i just checked and my idle is about 800. sorry bout that.

 

[vtecNSX1]

I ordered the supertune ecu from SOS so well see if that fixes the problem.

 

[RP-Motorsports]

A couple extras....

Honda ECU's will kick in an early rev limit if low on oil and/or gas.
(but usually lower like 5k)

Oil Pressure could also affect it.

Hopefully a new ECU will solve it.

 

[vtecNSX1]

my oil is fine i checked it recently, and it has done this even after a fresh oil change. Gas is fine also. the oil pressure is fine too, i think it must be something with the ecu so hopefully this will fix it.

 

[vtecNSX1]

ok i just installed my new supertune ecu and it is awesome. I think that the problem is my tach is somewhat incorrect because before the rev limiter would kick in at 7400 and now it kicks in at 7800.

 

[DutchBlackNsx]

Hey, why not post your speed at rev.limit in 2nd or even better, 3rd gear?