Possible 2 step for stick shift cars...

[QUASAR]

Just thinking about this...

Is it possible to set the park/neutral rev limit lower (say 2500 rpm) on a stick car, and leave all the other rev limit parameters alone. I guess it all depends on how the computer recongnizes park/neutral in a 6 speed. My guess is when the MPH=0 the car is considered in park or neutral. Once you drop the clutch and the car moves (MPH>0) the rev limit would turn off and retain the "in drive" limiter. So by setting the P/N rev limit you could create your own 2 step....

My car is in the body shop or I would try this now. The idea has been burning me up though. Someone try it! If it works it would be great for launching at the track/street!

[Dirk_Diggler]

I was told this cant be done and is dangerous to do. That parameter cuts fuel. Not al the fuel but some and leaves a nice mixture to detonate its tail off. The harlan 2 step that cuts spark would be better.


Can Ken, Keith or Gameover onfirm this.

[QUASAR]

Doesn't the same thing happen when you hit your regualr rev limiter? The engine doesn't blow up then, why would it be any different at a lower RPM. I do see what you are saying, but why didn't GM cut spark then?

[Dirk_Diggler]

My response was based on word of mouth, I guess we will need HPTuners and company to reply. I aasked the same question as you did because I thought fromthe factory sprak retard was 6200 and fuel cutoff was 6500 or something like that

[Casey]

We will take a look into this to make sure.

The way to go is to cut the fuel, not the spark.
Raw unburned air/fuel going out the exhaust will turn
the Cat into a blowtorch.


Ken

[QUASAR]

If it cuts fuel COMPLETELY on a certain cylinder, then it wouldn't be a probelem (i would think)

I was the one that was holding the vid camera for harlan when the 2 step was first tried out on a car. And I almost got burned from flaming exhaust! Lol!

Oh and I dont have cats anyways...no emissions testing here in MI....

[Dirk_Diggler]

We will take a look into this to make sure.

The way to go is to cut the fuel, not the spark.
Raw unburned air/fuel going out the exhaust will turn
the Cat into a blowtorch.


Ken

Cool!!!!!! Looking forward to hearing aresponse as I am a stick guy in need of some type of two step

[BlackWS6]

Very interested in this as I still run cats and can't use Harlan's 2-step because of the cats.

[QUASAR]

I tried it out at 2500 rpm. It does work, but its not as "quick" as say pulling the spark like in a harlan unit. The car is considered in park/neutral when ever the clutch is in or stick is in neutral. Dead stop, rolling, whatever, as long as you are not in a gear with the clutch out it is considered P/N and the lower limiter is used.

That kind of stinks because you cant rev it up while you are rolling, but how "livable" it is depends on where you set the rpms. On a dragradial I figure launch rpm would be around 3000 so it may not be too bad.

[Dirk_Diggler]

TTT any word on this.

Quasar maybe there is a delay that can be used that we dont see in order to make this work

[Dirk_Diggler]

TTT

[BlackWS6]

Well, my HP Tuners should arrive next week (just in time for Bowling Green!) so I'll play around with it and see if it's livable for doing a launch at the track.

With my non-sticky tires, I usually launch ~3000 RPM and feather the clutch.

Is HP Tuners saying that the P/N rev limiter cuts fuel? If so, it should be cat-friendly.

[arthansen]

I have a V6 M5 and I set the P/N rev limiter to 3000 rpms (my launch rpm). I then did a few practice launches and it works great. You can't floor it because (I think) it tries to go into PE mode but with about half throttle, it levels off nicely at 3000 rpms. When I let the clutch off, the transition is perfect. I adjusted my peddle so the clutch switch is very sensitive. If I let off 1-2 mm, the switch is deactivated. As soon as I let off, the RPMs start up and the clutch engages. I will try this at the track next time I go. I will post the results.

p.s. If I am rolling, the limiter does not effect anything and I can rev all I want?!

[Dirk_Diggler]

Before we get al gung ho about this i want to make sure it is either cutting ALL fuel or spark. If it cuts some fuel and leaves spark that could be a nasty outcome as you would detonate yourself to death

[arthansen]

We are using the RPM Fuel Cut Off vs Gear. According to the help file:

RPM Limits
The VCM has a number of RPM limits that disable fuel if exceeded. The Cutoff RPM is the RPM at which fuel is disabled and the Resume RPM is the RPM at fuel is re-enabled.

It cuts fuel (all of it) and does nothing to spark.

[Dirk_Diggler]

What about the p/n fuel cutoff.

My rev limiter (what you are using) is set to 6700 i would like more information on the Park neutral option. But i guess from what you say that holds true also. I will verify if ALL of the fuel is being cut via WB

[arthansen]

The P/N Fuel cut off is exactly what I am using. From the documentation, it sure looks like all fuel is cut and it sure acts like it.

I will look at it with my WBO2 and see if I can see anything. I am not sure what the difference would be from some fuel or all fuel to the WBO2. I would think they would both show as lean (excess 02). I will give it a try.

[Dirk_Diggler]

Some fuel would be less that 20:1 all the fuel will be 20:1 (which is the EFI limit)

[arthansen]

While bouncing off the limiter at 3000 rpms, the A/F ratio consistently hits 20-22 AFR.

[BlackWS6]

OK, where are you guys setting this? I set my P/N rev limit to 3000, with the re-enable at 2990. I've got the M6 tranny and want to launch at 3,000 RPM.

When I'm sitting still, shifter in neutral or first, clutch in, I can rev all the way up. I didn't see exacly *how* high it would rev, but it went to 5K in a hurry when I gave it some gas.

I double checked by downloading the tune from the car and checking it in editor ... yup .. it says 3000 RPM.

What gives?