ukfinance2002

I have had a couple of odd occurrences with the rev limiter at my last couple of autox and wanted to know if the same happens in your car.

Depending on the course, there are times when I will bounce off the rev limiter before entering a braking zone. Normally it sounds like ignition cut and goes "pop,pop,pop" at a rate of about 3-4 per second.

But as of late, I have been getting what sounds like fuel cut from time to time where the car just goes "buuhhh" with no additional hits of the limiter.

The first time this happened, I thought that maybe I had lifted at the first hit of the rev limiter but I have been able to duplicate it with the throttle to floor. Once it recovered from the "fuel cut" it went back to ignition cut.

Please keep in mind that this is not from the infamous left hand sweepers and I normally race with a full tank on slick asphalt.

I have flipped through the service manual with no leads on what might be causing this. Also, I'm pretty sure the ecu controls both fuel and ignition cut.

Thanks,

Chris
(when I do a search all I get are all the new s2k owners afraid of over revving)

payneinthe

I have never experienced it, but this sounds like what people refer to as the "hard limiter".

This will give a *slightly* better set of results, but still hard to find. Look at PilotSH's (James Yom)'s messages about Atwater and Houston NTs.

https://www.s2ki.com/forums/index.php?act=S...2rev+limiter%22

Jonathan 2.4

I hope I'm understanding you correctly, but why not just shift before you hit the rev limiter? I assume because of your name that you have a 2002 and your limiter should be 9kRPM's.

Or are you saying there is a fuel cut somewhere before the actual 9kRPM?

Jonathan

jzr

Sometimes shifting isn't the right thing to do.

Chris, the car exhibits 2 different rev limiters - one is a rapid spark cut, the other, sometimes referred to as the *bleh* limiter, is a fuel cut. There have been several different theories as to why and how the computer selects which one to use, none proven conclusively.

This video has a couple hits of the limiter in its first 20 seconds. The first one at the top of 2nd gear is the spark cut, the second time at the top of 3rd (where you'll see my head fling forward as fuel gets cut before braking for the hairpin) is the fuel cut. Both are perfectly normal, though the fuel cut is certainly more annoying.

ellisnc

JZR, do you actually have data supporting a "spark cut?"

As far as I know there is no such thing. Everything is a fuel cut. The difference you feel in a hard and soft limiter as you describe them is only the difference of the refueling RPM. Therefore, what feels like a soft fuel cut would refuel at let's say 8800 if fuel cut off is at 9000 and the hard fuel cut would be a refuel at 8500 for example. If you keep adding to the counter that decides where to refuel (which is the reason you get the lower refueling point in the first place) then the engine speed at which you refuel will continue to be reduced.

You can try this in neutral if you'd like sometime... I'm not sure what the lower bound is but I wouldn't be surprised if you could get the refueling point down to about 3-4k rpm after 20 seconds or so.

jzr

I'm trying to remember if we monitored A/F in those situations on the car to see which it was, but don't recall. The "nicer" limiter may very well be a rapid fuel cut.

modifry

I'm curious, how would you tell by A/F if it's an ignition cut or fuel cut? If they (for instance) cut every other cylinder firing as a soft ignition cut, wouldn't they stop the injector for that cycle too?

I've seen documentation in the manual of the fuel cut, but not about an ignition cut. Do you know of any documentation for it?

One more thing - SHIFT BEEPER!

Gregg Lee

tape is not data?

Anyway this does happen. When I get the total cut it has always been on a second rev limit in quick succession.

jzr

Spark in the absence of fuel would lead to a lean condition; fuel in the absence of spark should lead to a rich condition. Cutting off both would still probably make things lean, since the motor is still pumping air.

Beeper? I don't need no beeping beeper! Still, if it keeps someone else from blowing up their motor, I'm all for it.

DSF_S2k

How can cutting off both make things lean when the motor is pumping air? I thought that rich and lean conditions within the engine were based on combustion of the fuel air mixture. So if there is no combustion, then it can be neither lean or rich. Is that not a correct assumption?

Dale