It has nothing to do with driving it on the street only when I am stopped and trying to make alot of positive manifold pressure. When I am rolling down the street I have as much timing as I can until it comes into boost

 

I'm guessing Ren is using some type of box with a 12v input or ground input that when the clutch is dis-engaged and an input switch active it pulls his timing he has set to be pulled then and only then.

That way he has full normal timing when driving around and cruising so when he rolls into it he is using the same method as we are.

 

Yea, that was kinda my point, Like you said, there is a difference between rolling into the throttle rather than hammering it down like at the track...

 

Right, which is why I asked you what scenario you were in when you used that method of tuning to spool the quickest/best.

 

I had one tune which worked for me at the track and on the street, I was deep into the negative in the PE mode in the RPM area basically from idle up, Then I went into the maf and monitored the KPA from the same RPM and adjusted so it would not be pig rich, In that, I added timing in those KPA - RPM Areas. Now on street driving, rolling into the throttle, like say entering the highway, there was a very slight initial lag, but I mean a very little, Hammer down from a dig, would pull the wheels...

 

light load or as its coming into boost bring it to 35* timing and 13.5 AFR and taper that off to peak tq
this applies to your entire PE scenario as well as on the transbrake. For a M6 car either do that or anti lag it with 5* timing and 11.5 AFR

Heres a discussion from 07 we had in here
https://ls1tech.com/forums/forced-in...me-tuning.html

 

The afr becomes irrelavent from what I have seen when I 2 step it. I use the same amount of fuel @7 psi on my two step as i do under load while driving. But the wideband reads leaner when I am on the 2 step. I don't know the official or technical reasons for this I just attribute it to the combustion events being moved in the exhaust manifolds.

 

because a wideband reads oxygen not fuel. since all the fuel isnt being burned and there is extra available oxygen so the sensor reads lean.

 

I think that the pulse hose up the WB readings as well.

I use a very similar strategy to what Grr mentioned. 35-38* to reach the 2 step RPM. Then drop it to like 25* on the 2 step and then it pulls out another 5-7* by 5.5K RPM and flat to peak around 18*.

Same goes for the fuel. Start lean and once on the 2 step richen way up to target (11.5 AFR).

Moe, you mention PE TPS % and how its an issue but it shouldn't be. When you launch the car, you should be in PE mode because you should be at 100% TPS. Same is true for when you get up on the 2 step. So not really sure I'm understanding that part of your concern.

 

The problem without a 2 step, the % TPS vs PE comes in at I think about 30% throttle or so. now if you are revving say to 4+ grand at launch, then the lag is not as noticeable, but if you launch at a lower rpm and do not have all parameters adjusted, the transition from the 30% to WOT will cause the PCM will dump fuel causing the car to fall on its face until it reads WOT then will take off like rabbit with its *** on fire. Again this is just what I experienced. I have tuned cars that were like stated, that like being rich with a little less timing

 

thanks! makes good sense, never really took the time to put the two together.

 

So how are you guys determining what afr to target when on the 2 step if it is dumping fuel and giving a false lean reading?

 

Turn the two step off and put it at that RPM on the brake.

Also there is a hysteris for PE to keep it from coming on until whatever throttle percentage you have it set at.

I like to use open loop fueling for everything up to atmospheric pressure then let PE take over and use BE for over boost situations only.

So that way my open loop fueling tables control everything until basically I see boost then PE takes over. This way I can keep the open loop fuel adder table lean to help get up on the converter, then slowly start to taper fuel in as kpa rises to over 95kpa with PE and keep slowly adding fuel until I'm around 4psi then put the commanded fuel coefficients in that I would run down track and above 4psi to achieve my desired commanded AFR.

I also use AFR spark correction to add timing to my main table while I command my desired fuel coefficient I see on the foot brake while spooling(usually 13.5:1-12.8:1 and I'll add between 8*-14* to a base of 26*-28*) and then as I see boost rise I slowly take that added timing away until I hit 3-4psi and take the spark correction back to 0* and allow the timing coefficients that are in the main table that are used in full boost past 4psi(usually around 16-18*) to be the only units actively in use. Once I hit 3-4psi on the foot brake I let PE go to 12.0:1 at 4psi and then ramp more fuel to 11.6-11.5 at full launch boost and all the way down track as like Los said it really allows the fuel to light off as you have moved the combustion into the headers closer to the turbine.

I've found this method to give me and others I have helped the best spool time they have ever had as it allows you to be lean and mean on the foot brake, add in extra timing without messing with the main timing table that you use for down track boost, allows you to pull that added timing back out and add the fuel you need in progressively for boost and not flood the motor out with fuel when you're trying to build boost to get up on the converter/2-step.

 

Martin,
I know this an old post but I still would like to thank you for giving that explanation to us novice tuners. Im sure that this thread has helped numerous people.