Gas Pedal Delay

Originally Posted by DIGItonium

The automatic Z I test drove over a year ago did not have this issue, and the temps were cooler at the time it was being tested. It was the first time testing a 370Z, and my initial impression was that it was eager to rev to past 3k with little throttle tip in. I was sold and ordered the 6MT.

What I would like to see done since I don't have the funds to get the appropriate tools, is to get a data acquisition board of some sort to record the voltages for the gas pedal, ECU outputs, VVEL outputs, stepper motor inputs, and temperatures in different areas including the stepper motor assembly. All of this data would be logged and graphed to observe temperature and the relationship of the signals controlling throttle response.

The gas pedal voltage should be 100% linear from 0-5V.
The ECU throttle output may not have a 1:1 correlation to the gas pedal potentiometer.
The VVEL controller, which I know nothing about, I will assume is a black box with input and output to control the stepper motor.

Somewhere along the lines of capturing this data and graphing it we should see somewhere in the system of gas pedal travel (2nd gear, pressing pedal from position 0 to max) we should be able to graph the delays and compare it to temperature. Obviously something's getting hot and slow. Has anyone felt the stepper motors? That thing is scorching hot. I'd be curious to know where the VVEL "box" is located as well.

[EDIT] Service manual indicates there are terminals for the VVEL Control Shaft Position sensor, so the voltage levels can be measured here. Then there's the VVEL Actuator motor which we can probably log and compare with the sensor values. Just for kicks, we can log the TPS sensor as well.

Originally Posted by wilsonp

Actually, hardware like USB DMMs to record voltage over time isn't expensive, though the data logging software can be. I believe you can even do logging with some TI calculators with the right kit. The problem might be syncing with an OBD II logger.

My 2009 Auto hasn't exhibited the problem at all, so I can't do any testing.

Originally Posted by DIGItonium

Datalogging software isn't needed as long as the voltages can be recorded over time and stored in a comma delimited text file. I use open source library, ZedGraph, to graph data with several hundred thousands of points. If you guys like, I can write a simple program that uses this library to import individual csv files and plot them as separate graphs or overlays.

Datalogging with UpRev is one thing, but we need to acquire signals at the source (I/O control signals and driver output). The ECU and VVEL module output signals to control the throttle and VVEL actuators and each has its own position sensor, but I don't know the system well enough to determine if the control signal output to the actuator goes from A to B in X milliseconds that the actuator is expected to physically change positions from A to B in X milliseconds as well.

In other words, we might have a situation where the control signal expects the actuator to move from point A to B. The actuator does move from point A to B, but there is no mention about how fast it should get there to meet the timing tolerance. It is like playing an FPS game with a wireless keyboard and mouse getting pwned from the 0.5s lag.

Originally Posted by IcedZ

Good point.
Does anyone have a scrap OBD-II cable they would be willing to mail me? I literally just need the cable to plug into the car. I will be breaking it out into a breadboard, so I preferably do not want it coming from something working. I have an NI 14 bit DAQ that will be perfect for this.

Originally Posted by DIGItonium

Oh snaps... how many channels? I guess we can start with one side (i.e., left/right actuators and sensors) with common inputs (gas pedal potentiometer, temps, etc.). Definitely create the "cool" logs where the car behaves normally, and "hot" logs where the car starts lagging. I'll try to find some time this week to write a small program using ZedGraph.