Nissan 370Z Forum

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-   -   Gas Pedal Delay (http://www.the370z.com/engine-drivetrain/20402-gas-pedal-delay.html)

IcedZ 09-12-2010 03:35 PM

Quote:

Originally Posted by DIGItonium (Post 717744)
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.

THIS is EXACTLY what I've been trying to get!

6spd 09-12-2010 03:56 PM

that kind of scan gear is gonna run someone quite a tab, if it is even possible to get. like i said, it is gonna take a cooperative dealer, and that is more scarce than... well something that doesn't exist!

wilsonp 09-12-2010 04:01 PM

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.

flashburn 09-12-2010 04:14 PM

Last time I was doing data logging with Uprev I noticed there were like 4-5 different VVEL things that you can log/monitor. If this would be useful to anyone, I can find out what things it can log. I can't do any useful logging though since I can't reproduce this problem either.

IcedZ 09-12-2010 11:13 PM

Quote:

Originally Posted by wilsonp (Post 717935)
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.

Exactly. The actual hardware isn't that expensive. However, the software can be. And it's very niche software. Interfacing with OBD is the hard part (for me anyway).

DIGItonium 09-12-2010 11:29 PM

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.

wilsonp 09-13-2010 12:03 AM

But I think the 1-2s lag combined with it happening primarily when warm means it should be possible to narrow it down, just a lot of work.

IcedZ 09-13-2010 12:18 AM

Quote:

Originally Posted by DIGItonium (Post 718410)
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.

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.

DIGItonium 09-13-2010 07:13 AM

Quote:

Originally Posted by IcedZ (Post 718521)
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.

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.

IcedZ 09-13-2010 10:53 AM

Quote:

Originally Posted by DIGItonium (Post 718675)
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.

8 analog channels, 12 digital I/O channels.

6spd 09-13-2010 04:32 PM

sound like you guys have a good grasp on this. good luck! Im very interested in the results if you can get any!

DIGItonium 10-03-2010 12:18 AM

I've not had time to write the graphing program. Once I know what the log file looks like, then I can write the code to parse the rows and columns of data.

Today ambient temps hovered around 65F for the high. With the engine bay cooler than usual throttle response is the way it should be. I can press the pedal close to 50% in 1st and 2nd and be able to get the car moving immediately with no delay.

Of course, after a longer duration of the drive (15+ min.) the throttle starts lagging and doesn't open up as much as anticipated. I can floor it in 2nd and 3rd. The exhaust gets loud, but the car doesn't seem to accelerate much at all. It's very gradual as if throttle isn't opening up fully.

Then I make a quick stop to get stuff. Get back in and get moving, and throttle response is normal again for several minutes.

I'm not quite sure if Sprint Booster is going to fix this problem especially when I try to floor it and the car barely accelerates, but only when it's cooler.

DIGItonium 10-06-2010 12:46 AM

Heh... I'm pretty sure you guys are annoyed by my bump posts for this thread. I'm wondering if all this lack of response has to do with the current programming of the VVEL actuators. After doing some reading about the VVEL TSB for G37 owners, some owners were complaining that the reprogrammed ECM made the engine unresponsive. So for those who wonder about VVEL software adjustments, it is possible, but at the price of enduring the knocking noise?

Here's a quote and response:
MyG37 - View Single Post - ITB08-028a - Noise from bank 2 VVEL actuator (amended 9/3/08)

From FreshAlloy:
Quote:

Went back to the dealer and they said they have a fix. They told me there is a programming fix that will take care of the problem. They did the programming fix and now the car feels like it doesn't have the torque when it shifts at low to medium throttle, as in traffic driving. It feels almost dead when it shifts until it starts gaining RPM's. They say the only problems with this fix is it causes a starting problem and an idle problem. Either they don't know or they don't want to say. Any tech out there have an idea?

Valentino 10-06-2010 03:09 AM

^ Interesting

J. Dub 10-06-2010 11:38 AM

If this problem were a dinosaur, it'd be a failaciraptor.

Count me in as someone w/ the lagging acceleration problem.


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