Launching with a two step

[grape of wrath]

Anyone use a msd two step to launch with. I've tried using it it a couple times with no success. I have it set to 3000 rpm's and it does its popping thing but after I release the monetary button the car hesitates before getting up to speed. It seems like it's loading the cylinders with gas too much. Any thoughts or secrets?

 

[Turbo-Fun]

Anyone use a msd two step to launch with. I've tried using it it a couple times with no success. I have it set to 3000 rpm's and it does its popping thing but after I release the monetary button the car hesitates before getting up to speed. It seems like it's loading the cylinders with gas too much. Any thoughts or secrets?

I have used a two step with no problem. I don't have any secrets with using it. It's an MSD DIS-4 used in conjunction with a trans brake. I will be installing an AMS 500 boost controller for next years racing season. I index and bracket race so I am shooting for consistency. I also use menthanol injection and will be adjusting that to delay the alcohol turn-on point because of the two step. But I am launching strong with a best of 1.54 60' on Hoosier DR's. Maybe you need to take some idle fuel or low RPM fuel out of it. If you have alky, change the turn-on point to 200 rpm's over your programmed launch. Make sure to increase the ramp speed for the alky as well. Sorry I couldn't be more help.

 

[Turbo-Fun]

I just rememberd something - You cannot keep the gas pedal to the floor while on the two step. I did have a problem when I first installed the two step and I was keeping it floored while on the two step. The motor did not like this at all. I've learned this from others but can't exactly explain why. You can initially floor it to get the RPM's up but once on the two step, come up off the floor to about 3/4 pedal or just enough to hold it on the two step. Try this before making any adjustments. This should correct your problem.

 

[TurboBob]

the biggest issue I am aware of when launching is that you need to keep whatever control system you have from correcting from the wideband while on the limiter. the wideband will show a very lean reading when the 2-step activates (from all the unburned oxygen in the exhaust).

Bob

 

[Turbo-Fun]

the biggest issue I am aware of when launching is that you need to keep whatever control system you have from correcting from the wideband while on the limiter. the wideband will show a very lean reading when the 2-step activates (from all the unburned oxygen in the
exhaust).
Bob

O.K. That makes Sense. That must mean that unburned oxygen equals unburned fuel correct? Any suggestions on how to keep the wideband from correcting while on the limiter? I have the PLX wide band.....

 

[TurboBob]

its not the PLX doing the correction, but (probably) the TT chip.

So, gotta pull Eric into the conversation.

With the Maft Pro, the thresholds for starting the correction are adjustable.

Bob

 

[aminga]

its not the PLX doing the correction, but (probably) the TT chip.

So, gotta pull Eric into the conversation.

With the Maft Pro, the thresholds for starting the correction are adjustable.

Bob

He starts the the correction based on MAF numbers. I don't remember what the midboost is but the WOT correction is at like 250 (maybe higher) so as long as you keep the AF out of that range it shouldn't correct.

With the latest PLC you can see when it starts.

 

[Turbo-Fun]

OK This is getting interesting. We will get Eric involved simply because he is the chip GURU for sure. My race season is over but next year I was going to play with the adjustments for Razors alky. There are two knobs in the secret black box that comes with the system. Julio pre-adjusts these for a given application. One knob adjusts "when" the alky comes on, and the other adjusts the ramp speed of the alky. If you delay the alky startup you must increase the ramp speed to make up for the delay. So my point is to at least take the alky out of it while it's on the two step and see what that does. As I stated above I got around the A/F correction by not keeping the pedal to the floor. Inconvenient but it worked for me. Prior to that if I held the pedal to the floor on the limiter it would act all crazy. More to come.....

 

[Eric Stage I]

On the SD chip, mid boost closed loop is turned off by default. The mid boost to WOT threshold is set to 15psi boost, but you can change that. So if you are on the 2-step and build say 18psi boost, then set the mid/WOT threshold to around 20psi, so WOT closed loop correction will not turn on until 20psi.
As far as the 3/4 throttle thing, I would have to see a log to see if it's a fuel related thing.

Regards,
Eric

 

[Turbo-Fun]

That sounds good. The 3/4 throttle is used by several guys around here that have the DIS-4 two step. Can't explain why, it just works better.
I think You've answered our question. I won't have the mid boost / WOT issue next year anyway because I'm installing a boost controller and I won't be launching with more than 10 psi at best. So I'm good.

 

[dentmasters01]

I use a msd-dis4 as well and have no prob. launching off the 2 step with the peddel on the floor. I use a xfi system though.