VDC quirks after UpRev
 

I'm not sure if this is psychological or real.... I have been noticing a distinct difference in engine behavior with the VDC program turned off compared to having it on. All of this after I got my ECU UpRev tune.

With the VDC turned on: No noticable engine knock, better torque "feel" at low (under 2k rpms) revs, no initial start-up knock.

With VDC turned off: a noticable engine knock at low rpms (under 1K), slight hestiation between 2000 to 2800 rpms, and a slight knock at initial cold start-up.

Someone tell me I'm crazy... or is this real?:ugh2:



(Serious responses only, please:tiphat:)

Can you capture it on video?

Uhh.... not really.

Can you log on Cipher to see what the timing is doing and throttle position?

No, I didn't get the cable.

It's really not an issue. I find that the engine is perfect with the program on. I was just wondering if anyone else has noticed this. Since I mostly drove the car with the program turned off. But since the tune, I drive it with the program turned on.

Hmmm I wonder if my cable will allow us to log with Cipher? I'll check into that

I don't think so. Your license is different than mine. And when the software seaches my VIN, it won't allow a different license to have access. (The license software is built into the cable.)

Your Crazy!!!!!!!!!!! LOL J/k. I never had these issues but I do feel a difference with the VDC off in a good way. On I feel the car hold back more often almost like I'm losing traction when I should not be. I have even had VDC blink on my dash if I pop her down to like 3rd at highway speeds and punch it. I know I'm not losing traction just weird.

Does the knock happen while on the aggressive map only? What happens when you switch to the normal UPrev map then turn VDC off. I'm planning on getting the tune done but wouldn't really want to deal with glitches or bug related to UPRev.

Me, I notice the opposite.

Yeah, I've noticed the wheel spin indicator lamp on the dash light up under a full-throttle burn too (with the program turned off). That's the abs sensor noticing a very slight (you'd never feel it) "wheel starting to spin" situation.

If you've made changes to the tire diameters (new tires and/or wheels) that could affect VDC's sensitivity as well. But the engine knock / hesitation thing is troubling. Have you tried reflashing to stock and back again, and experimenting with both?

License only matters for flashing, not logging.

Well, thanks for the ideas. But I'm not looking to "solve" this issue. The engine performs incredibly with the VDC on. I was asking if anyone else has encountered this (?). Re-flashing would ruin my tune and I'm not interested in starting over.

My question was; is anyone else noticing this issue with the VDC on/off?

I only had one map done and I cleared the OEM one. I didn't see any point in switching maps for the kind of driving I do.

VDC on/off shouldn't affect your engine one bit, when not in the process of slipping and correcting. By reflashing, I mean flash back to OEM, then flash back to the exact same flash you have now. UpRev or your tuner should have provided you with both flash files (a "back to OEM" flash, and your tuned flash, as files). You wouldn't need to start over, and it would eliminate the UpRev as the issue if VDC continues to do this on the OEM flash.

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....

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.

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.

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).

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.

:icon18::bowrofl::inoutroflpuke:

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