VDC quirks after UpRev

6MT · 09-01-2011, 02:45 PM

Quote:

Originally Posted by wstar

UpRev or your tuner should have provided you with both flash files (a "back to OEM" flash, and your tuned flash, as files). VDC

Yes I know, and he asked me if I wanted multiple maps. I didn't see a need for it. Besides, this "issue" is not a serious one. When the program is on, the engine performs incredibly (and it defaults to on when you start the engine). And when it's off, the performance is "minimally" different. (Pretty hard to notice.)

So..... back to the original question....

Zat_Zuma · 09-01-2011, 02:49 PM

Wow I've just read about the ABS/VDC controls and what it uses for inputs and outputs.

My best guess is that the ECM is cutting the fuel to the injectors and partially closing the throttle bodies from a false reading from one of the sensors. This may be what is causing the lean condition to cause knock. Why this is happening when the VDC is turned off is anyone's guess. It may be as simple as a bad switch, to as complex as a faulty ECM controller and it may be even the UpRev programming. There should be lots of DTC codes to possibly show where the problem area is. Going back to the stock tune would definitely answer the question of whether it's programming or not.

The check procedure for the ABS controller which is tied into the VDC controllers and the ECM fuel control is staggering and a consult computer is required. A simple check is to check the connectors on the ABS controller, located by the brake fluid reservoir, and the VDC on/off switch. Make sure they are seated properly.

I'm afraid to say if that doesn't cure it, a trip to the dealership is in order to troubleshoot the entire ABS system.

6MT · 09-01-2011, 02:53 PM

Quote:

Originally Posted by Zat_Zuma

Wow I've just read about the ABS/VDC controls and what it uses for inputs and outputs.

My best guess is that the ECM is cutting the fuel to the injectors and partially closing the throttle bodies from a false reading from one of the sensors. This may be what is causing the lean condition to cause knock. Why this is happening when the VDC is turned off is anyone's guess. It may be as simple as a bad switch, to as complex as a faulty ECM controller. There should be lots of DTC codes to possibly show where the problem area is.

The check procedure for the ABS controller which is tied into the VDC controllers and the ECM fuel control is staggering and a consult computer is required. A simple check is to check the connectors on the ABS controller, located by the brake fluid reservoir, and the VDC on/off switch. Make sure they are seated properly.

I'm afraid to say if that doesn't cure it, a trip to the dealership is in order to troubleshoot the entire ABS system.

The situation has never thrown a code, Zat. Good ideas, though. I'm really not worried about it. It has taken me a couple of weeks of driving to notice it, so it's really a small issue. And besides, having the "nanny" turned on is not such a bad thing.

wstar · 09-01-2011, 03:08 PM

Quote:

Originally Posted by 6MT

Yes I know, and he asked me if I wanted multiple maps. I didn't see a need for it. Besides, this "issue" is not a serious one. When the program is on, the engine performs incredibly (and it defaults to on when you start the engine). And when it's off, the performance is "minimally" different. (Pretty hard to notice.)

So..... back to the original question....

I know it's irrelevant, but just in case others are reading this. I don't mean maps. I mean a whole flash file that's just your stock ECU like the factory shipped it, with no uprev software in it and no map switching. UpRev gave me this file when they first shipped me my cable (along with their crappy canned tune file w/ 5 maps on it).

wstar · 09-01-2011, 03:11 PM

Quote:

Originally Posted by Zat_Zuma

My best guess is that the ECM is cutting the fuel to the injectors and partially closing the throttle bodies from a false reading from one of the sensors. This may be what is causing the lean condition to cause knock.

The engine should never knock if the ECU cuts fuel. The ECU cuts fuel in the same way for all of its engine limiting (the normal rev limit, the limp mode rev limit, VDC) as well as anytime you engine brake. When it does this, no fuel is injected at all, and the cylinder becomes an air pump. There's no lean burn happening (or shouldn't be, barring some failure). I believe in most of these scenarios there's a soft limit first, which basically modulates the drive-by-wire throttle input (like lifting the gas pedal), then a harder limit where it cuts out fuel delivery.

6MT · 09-01-2011, 03:15 PM

Quote:

Originally Posted by wstar

UpRev gave me this file when they first shipped me my cable (along with their crappy canned tune file w/ 5 maps on it).

John@Z1 · 09-05-2011, 04:03 PM

Get a cable and log it. Then send the log to your tuner and see if they see an issue.

09-01-2011, 02:49 PM	#17 (permalink)
Zat_Zuma A True Z Fanatic Join Date: Nov 2008 Location: Edmonton, Alberta ...eh Posts: 1,171 Drives: 2017 Touring auto Rep Power: 19	Wow I've just read about the ABS/VDC controls and what it uses for inputs and outputs. My best guess is that the ECM is cutting the fuel to the injectors and partially closing the throttle bodies from a false reading from one of the sensors. This may be what is causing the lean condition to cause knock. Why this is happening when the VDC is turned off is anyone's guess. It may be as simple as a bad switch, to as complex as a faulty ECM controller and it may be even the UpRev programming. There should be lots of DTC codes to possibly show where the problem area is. Going back to the stock tune would definitely answer the question of whether it's programming or not. The check procedure for the ABS controller which is tied into the VDC controllers and the ECM fuel control is staggering and a consult computer is required. A simple check is to check the connectors on the ABS controller, located by the brake fluid reservoir, and the VDC on/off switch. Make sure they are seated properly. I'm afraid to say if that doesn't cure it, a trip to the dealership is in order to troubleshoot the entire ABS system. __________________ [B]2009 & 2017 370Z Touring Sport Autos SOLD Last edited by Zat_Zuma; 09-01-2011 at 02:55 PM.

09-05-2011, 04:03 PM	#22 (permalink)
John@Z1 The370Z.com Sponsor Join Date: Nov 2008 Location: GA Posts: 1,589 Drives: Turbos Rep Power: 20	Get a cable and log it. Then send the log to your tuner and see if they see an issue. __________________ Z1 Motorsports will beat any advertised price on Nissan OEM Parts! 770-838-7777 ext 311 AIM: JohnatZ1 email: John@Z1motorsports.com

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