Ok, as most of you guys probably already know I like to race.

Specifically, bracket racing, which means it doesn't matter how fast you go its how consistent you go and how good your r/t is.

Not everyone can afford to buy slicks or dr's and would still like to compete. This is how to do it with a 5.5 gen drive-by-wire.

I experimented a lot with a stop under the gas pedal. I presently have an adjustable setup that is set at 40% WOT throttle opening. With this setup I can run a 14.8 et. With a 55% I have run a 13.7 on street legal tires.

However its still not consistent enough for bracket racing because the computer is still in control with that amount of throttle opening. You have to really go WOT for the computer to go into its premapped setup which is always the same.

So, here is what I did, I left the throttle set at 40% max at wot with the pedal blocked at that amount. Not much throttle movement but still fine for street and highway driving even agressively.

Then I looked at the setup for the drive-by-wire. It consists of 2 potentiometers that send their signal to the ECU. Their signals are voltage, one with a max of approx 2.5vdc and the other 5vdc each in proportion to the other. This vs a single po***iometer is for safety and reliabilty, if they both don't send their signal in proportion they ECU goes into limp mode. Same happens if the voltage is too high or too low.

What I wanted to was take off the line at 40% throttle and then go to 100% when the stock tires were able to handle the traction. This occured at approx 3500 rpm for me.

I measured the voltage going to the ECU at 40% throttle for both potentiometers vs the normal WOT voltage and calculated the resistance from the power supply for each potentiometer to get it to full voltage. I then connected each through a relay connected to my window switch through the cruise control on/off switch.

So I put the pedal to the metal and take off at 40% throttle while holding down the cruise control on/off switch, as soon as the rpm hits 3500 it goes to the real WOT not spinning a wheel and utilizing the WOT fuel map.

Consistency at its best. Tried it out Sat night and made 9 runs all in the 13.9 range, some with slicks, some with dr's and some with streets.

My new weapon for the National event coming up this weekend.

http://www.ihra.com/results/2005/nat...o/preview.html

 

Nice job! That is about as close as you can get without sneaking into the "full electronics" category. It sounds like this is the best setup for anybody who need consistancy on street tires. This is definitely the first time I've ever heard of tinkering with drive by wire. Good luck this weekend!

 

Wow that is ingenius. Nice work Jim.

 

I wish I could figure out my G35's problem. When I launch with a 2200-2400rpm flash stall, the G comes off the line hard, spins the tires about 5-10 feet, and then the car lays over and bogs till about 3500-4000rpms and then it takes off. It's almost a turbo-like surge in power. I'm convinced this lag is the way Nissan keeps the G35 off the heals of the 350Z. Typical 5AT G35 sedan 60 foots are in the low to mid 2.2 range while the 120lb lighter 350Zs 5ATs with a mere 7whp more consistently get 2.0s and sometimes 1.9s. It's terribly easy to get 2.2 60 foots out of the G 5AT, but any lower is damn near impossible. It's clear the car has the power, the Nissan nanny's are just getting in the way. According to the G35 FSM, the 5AT has a 2600-2800rpm stall converter. I just can't take advantage of it

 

You sure your ECU isn't playing games? I don't know much about newer ECUs, but I know they can be set to do some wierd things (i.e. timing retard, traction control crap, etc).

Also, if your FSM says that you have a 2600-2800rpm stall converter, then it really matters how they measure that stall. Most likely, that is the true stall of the converter and not the flash or brake stall figure. The true stall of a converter will usually be about 400-600rpm above what you will see on your tach with brake stalling it or launching off idle with perfect traction (flash stall).

 

Dave, what about yanking the ABS fuse

 

Last time I saw someone control engine operations through his window switch, he blew up his corvette at the line. Just be careful Jim.

 

Oh, it's definitely the ECU pulling timing and probably adjusting the drive by wire. Some speculate it might be the yaw sensor too. I'll probably pump my tires up really high next time I go to the track so that I can get more wheelspin and get over the bog quicker.

The FSM lists the stall of the converter at 2800-3000rpms in reverse, brakes on and 2600-2800rpms in 1st, brakes on. The FSM also says not to hold the brakes and the gas for any longer than 5 seconds when testing.


The only real advantage to doing this is that it allows you to do full on burnouts because it completely defeats the traction control.

 

Yeah, I agree. 5 seconds or longer will simply build up too much heat.

If you can get 2800 on your tach with the brakes in 1st gear, that is very good. It's MUCH higher than the 3L VQ and VE auto.

 

Dave I know exactly what you're talking about. Around 3200-3800 you get thrown back and the car starts to fly. I don't know what it is but it is cool to feel