Originally posted by N4Spd (hope u don't mind)


"hmm... I noticed something with my throttle position.

I recently bought an autotap to monitor what the ecu sees.

During full throttle runs, I never exceed 82% full throttle.
Maybe recalibrating the throttle position (using procedure in manual) will help me get to 100% and maybe some more power.

Just a thought... (I did disconnect the battery a while back
and ever recalibrated anything...)
"

Now is this a freak occurance, or is this some more built in hp limitations by Nissan?

 

I've often wondered the same thing. It would be an easy way for Nissan to detune the Z.

I think that Technosquare would have discovered it during their tuning sessions though.

--
Jeff

 

I'm surprised that there hasn't been more on this topic. The E46 M3 also uses a "throttle by wire" sytem. It has different settings that controll how fast and how open the throttle is when you step on the gas. I remeber reading that the Z was designed to have a nice smooth throttle response. I wonder if that means the throttle opens allot slower than it could.

 

Can anyone with a FSM tell us how to calibrate the throttle?

 

hi sschmuve,

thanks for posting here. I got lazy (1 month old infant on arm and typing with 1 hand with little sleep).

I saved the procedure from a posting a while back and will try to dig it out and try it on my car...

If it gets me close to 100% then I'll be a happy camper.

thanks,
rob

 

much more than what you have stated has been discovered, and its been implimented on every ECU thats been reflashed.

thats why i've been trying to express that the ECU reprogram is not just A/F and Timing, but the overall... driveability of the car

 

What is this "autotap" you speak of?

Is it cheap? Is it easy to install? I'd be interested in checking out my car if it was fairly inexpensive.

Thanks,
D'oh!

 

Some drive-by-wires are programmed so that gas pedal position dictates how much torque you feel, like BMWs and stuff. If you give it 50%, it'll give you 50% torque, even though that's not the same as opening it 50%.

Nissan's DBW system is the most lag free and smoothest I've ever driven, BTW. My Accord lags about a split second from a dead stop.

 

www.autotap.com

It basically hooks a serial cable form your ODB-II port to a laptop. It can monitor many of the electronics on the car.

I have one and it works ok, but a little slow IMO. I have talked to Autotap about it and they know it is slow for our cars. They said it has to do with the CAN system Nissan uses on our cars. It does a good job with one or two variables at a time, but gets slow after that.

 

do I smell a cheap mod???

hehe

 

"much more than what you have stated has been discovered, and its been implimented on every ECU thats been reflashed.

thats why i've been trying to express that the ECU reprogram is not just A/F and Timing, but the overall... driveability of the car "

What are you saying, that we need to take our cars back to nissan and get the ECU updated to fix this problem. is there a DIY to this? All i am reading is speculation. Whats the answer?

On my civic i had an APEXI VAFC and it showed 100% throttle when i floored it. but i had to reset the throttle by holding the pedal down for 10-12 sec while the key was in the almost on position!

 

I talked about this too... this was one of the reasons I got the TS ecu it modifies so that the throttle stay open completely... especially up top in the rpms... also for the nitrous boys and girls who need reliable fuel delivery....(not that this really means anything for the stock Z ecus since they run extremely rich over 5K) but anyways ummm.... ya

-non

 

Here are three companies that make scan devices for our car. One for Palm OS, one for Pocket PC, and one for either laptop or Palm OS:

www.auterraweb.com (Palm OS)
www.injectoclean.com (Pocket PC)
www.autotap.com (Palm OS or laptop)


Jeff

 

Nissan isn't going to change it for you, its the way they designed it for some reason.

 

If this is true, and the throttle only opens 87% at full throttle, that is absolute bull sh*t. The more I read and learn about this car the more I begin to become angered. It makes me wonder what the hell nissan was thinking when they made this car. Its a friggin sports car not a damn mini van, people want power and performance. I hope someone discovers a fix for this soon, and hopefully it wont cost an arm and a leg.

 

If this is true, and the throttle only opens 87% at full throttle, that is absolute bull sh*t. The more I read and learn about this car the more I begin to become angered. It makes me wonder what the hell nissan was thinking when they made this car. Its a friggin sports car not a damn mini van, people want power and performance. I hope someone discovers a fix for this soon, and hopefully it wont cost an arm and a leg.

 

dude read above... the ecu does FIX this "problem" and I wouldnt get too mad at nissan, they built this car very well, but they left much room for improvement and modification, just like any other car. (hehe what good is a car if you cant tinker with it)

-non

 

Please do the following in order to prove or disprove this.

Connect the scanner with the engine off and the car parked, in 1st gear (if 6spd, not what tranny position if an automatic). Take off the intake hose to where you can observe the butterfly valve. With the ingnition ON (not running) and the car in 1st gear, have someone fully depress the gas pedal. Compare the butterfly open % against what the scanner tool says. This is the only way to really check and see if the scanner is reading correctly.

Also would be good to do while running, but in neutral since the alternator raises the system voltage up some, but this is much more difficult to do (disconnected MAF sensor, loud engine revving).

Dan

 

I *KNOW* I've seen a post where someone described how to recalibrate the gas pedal. Unfortunately, I can't find it with the forum search.

My guess is that the gas pedal uses a potentiometer to measure how much you push it. Anyone that's ever owned an old analog joystick knows that these things change over time. They don't necessarily go bad but what used to be full throttle will slowly change as the brush wears away at the resistor coil. This could account for the throttle being off.

However, I would think something as critical as an electronic throttle would have all kinds of redundancy in it. For instance, full throttle and no throttle might have electronic switches triggered in addition to the potentiometer measurement. These could be used for dynamic recalibration.

Also, optical angle readout sensors would be more accurate that pots for measuring gas pedal position. They'd probably never need recalibration.

So in short, Nissan may or may not be detuning the Z. I'd be curious to see what the HP difference is between true full throttle and what was seen on the OBD-II scan tool.

--
Jeff

 

The system actually has two potentiometer type devices to measure throttle position. One varies from approx 0.7-4.2 volts, the other from 4.2-0.7 volts compared to throttle position 0-100%. The computer does some testing to make sure both values are in bounds and will eventually alarm if it detects something funny. I'm sure these devices are of much much much higher reliability than video game joysticks. I've also done testing on the voltage outputs of these devices (when I was going through ZEX nitrous kit installation problems). With the engine off the voltage would vary between 0.7-4.2 volts, but with it on and running it seemed to max out at 3.9'ish. But remember, the car is running and therefore the alternator. ALso remember you can only control the throttle butterfly with the engine off if the key is in the ON position and the car is in 1st gear on the 6spds.

Dan