She's acting up....

Premo34WV · 08-06-2009, 02:35 PM

So I'm driving a bit aggresively and as I downshift from 4th to 3rth and allow the car to coast, the synchro rev perfectly matched 3rd gear revs and I let out of clutch, then something happened....

Instead of engine breaking the car maintains speed or even very slightly accelerates.(on its own with my feet completely off of all pedals) Once I apply break pressure it stops doing this. No the accelerator wasn't stuck I was curious so I tried to duplicate the action and once again the same thing. This time I put my foot behind the pedal and tried to pull out, it wasn't stuck. It only happened at right about the 4k rpm range and for only about 3 seconds.
The action felt like something was up with the Synchro system, like it was trying to bump the rpms while i was in gear

This happened about an hour ago and is definitely cause for concern. Anybody ever heard of this happening?

dszombiex · 08-06-2009, 02:53 PM

Well, not quite the same but related to the synchro rev...

I have the 7AT. I was under the impression that the synchro rev is only on when the tranny is in sport mode for the auto and I manually downshift. Until a few days ago this has always been the case for me.

Well this past weekend when I was coasting downhill in full auto mode with my foot completely off the throttle, the car suddenly revved twice! It was a decent rev too like up to 4k or something. I drive in full auto mode when I'm lazy or during my daily commute to work all the time. Its never gone off in full auto mode before.

speedworks · 08-06-2009, 04:08 PM

I've had this happen many times with spirited on/off ramp driving. The car does feel like it accelerates, but I think it is only not braking (by the engine). I am not sure what or why the car does this - but it has done it since I have had it (Jan). It is only noticeable when I am at/near the limits in a turn (at no throttle).

fullmonty · 02-20-2010, 03:31 PM

Quote:

Originally Posted by dszombiex

Well this past weekend when I was coasting downhill in full auto mode with my foot completely off the throttle, the car suddenly revved twice! It was a decent rev too like up to 4k or something. I drive in full auto mode when I'm lazy or during my daily commute to work all the time. Its never gone off in full auto mode before.

Same with my 7AT, was going down a fairly step hill, foot off the gas just kind of coasting down at aprox. 40-45mph, the car downshifted but held the RPM at 4k. Didn't feel an increase in speed or anything, just held at 4k until I breaked. Took me by suprise but I don't think it's anything to worry about.

speedworks · 02-22-2010, 02:09 PM

UPDATE: Just took it to the dealer, and was able to re-enact the issue with a tech in the car. One thing I didn't think about was putting my foot in the clutch when it happens. He suggested it, and what do you know, the car went to 4500 rpm and maintained that rpm through the turn (or until I touched the brake or the turn straightened out). So, it was definately maintaining a throttle. Those with this issue should try the same thing. Anyway, the car is in their hands now; and hopefully they call with a option/solution.

Premo34WV · 02-22-2010, 02:39 PM

glad to hear this was reenacted with the dealer present. Please update us as this is still happening to me. And i agree it only happens at the "sweet spot" of the gear.

speedworks · 02-23-2010, 06:38 PM

Quick update:
They couldn't find any obvious issue to cause the problem (checked all wiring and sensors, and found nothing). They have a call into Engineering, and are awaiting an answer of what to do next - they will have the car for a few more days. Its supposed to rain around here the rest of the week, so no biggie for me.

I also put in a complaint on the PW sideskirts not being a perfect paint fit (like all of them). Again, they will be reviewed by a corp representative when they are back in town (the run around on that one).

noodles · 08-06-2009, 04:21 PM

i have heard of this before and more then likely what causes it is the that the rev match is designed so that when you downshift your going to be right back on the gas so it anticipates this and does it for you.

Nikon FM · 08-06-2009, 05:14 PM

Same thing has happened to me (many times) while working through back road twisties. I'm just calling it a feature

davidyan · 02-25-2010, 11:12 PM

Quote:

Originally Posted by noodles

i have heard of this before and more then likely what causes it is the that the rev match is designed so that when you downshift your going to be right back on the gas so it anticipates this and does it for you.

This ^^ sounds like a pretty logical explanation... Also notice that if you are cruising then move into neutral, when the snychro rev match kicks in (immediately), that it holds the revs for a long time before realizing that you are not moving into another gear (due to coasting in neutral) and then slowly allows itself to wind down. Thus, if you were to downshift and not manully get back on the gas, the synchro rev match is still electronically holding the throttle open for about 3 seconds or so. Because of this, any engine braking would be minimal, if any during that time period. One way to test would be to disable the syncro-rev match and try it again- you would engine brake much harder then.

shabarivas · 08-07-2009, 01:27 AM

Maybe the VVEL was throwing the ECU off.. interesting... lol my downshifts rarely end up near 4k

speedworks · 02-20-2010, 07:58 AM

Had to bring this back alive. After driving this car for over a year, I notice it a lot more, and have the ability to recreate it. Anytime I am on a long on/off ramp from a highway, and have a good speed going, and lift off the gas (to hopefully let the car decelerate), the car maintains the speed. Being close to the edge of comfort, it does make me a little nervous, as it is close to the edge of a slipping (and I am prepared to countersteer). So there are 2 inputs, good amount of steering input, and g-forces - it is either condition (or a combo of them) that creates this problem. Anyone else out there have this issue and have you had more time to diagnose it? I am at the point now that I am going to test it around my dealership, so that when I take it in (in the next week or 2) I can show them. I would suspect those that do DEs would feel this (if it was common), on long sweeping turns (which is the only time I feel it). I also notice that it will start to decelerate once the long sweeping turn straightens out (less g force and steering input), or I slightly touch the brakes. It's actually much easier to recognize it since I have installed the FI exhaust as you don't get the decel gurgle until it goes away.

Any others? After all of these Toyota issues, I wonder if Nissan has something similar; these electronic gas pedals concern me.

onekneedown · 02-20-2010, 09:38 AM

Quote:

Originally Posted by speedworks

Anytime I am on a long on/off ramp from a highway, and have a good speed going, and lift off the gas (to hopefully let the car decelerate), the car maintains the speed.

Why would you expect the car to significantly slow down just by lifting off the gas, especially if you are going at speed into a turn?

speedworks · 02-20-2010, 09:57 AM

Quote:

Originally Posted by onekneedown

Why would you expect the car to significantly slow down just by lifting off the gas, especially if you are going at speed into a turn?

I don't expect it to significantly slow down, but I do expect it, due to friction, to not maintain speed, as anyone should. Cars won't maintain speed, if you don't have an input like fuel.

Pharmacist · 02-20-2010, 08:57 AM

I read that porsche has a feature called engine torque drag control or something like that as part of the porsche stability management program. What it does apparently is that it opens the throttle a bit so that the engine revving down doesn't rev down too quickly and cause too much drag on the rear wheels and break their traction and lead to spinning out. Perhaps the Z stability control has a similar feature?

08-06-2009, 02:35 PM	#1 (permalink)
Premo34WV Base Member Join Date: Jun 2009 Location: Morgantown, W.Virginia Posts: 68 Drives: PW '09 370z Sp. 6mt Rep Power: 16	She's acting up.... So I'm driving a bit aggresively and as I downshift from 4th to 3rth and allow the car to coast, the synchro rev perfectly matched 3rd gear revs and I let out of clutch, then something happened.... Instead of engine breaking the car maintains speed or even very slightly accelerates.(on its own with my feet completely off of all pedals) Once I apply break pressure it stops doing this. No the accelerator wasn't stuck I was curious so I tried to duplicate the action and once again the same thing. This time I put my foot behind the pedal and tried to pull out, it wasn't stuck. It only happened at right about the 4k rpm range and for only about 3 seconds. The action felt like something was up with the Synchro system, like it was trying to bump the rpms while i was in gear This happened about an hour ago and is definitely cause for concern. Anybody ever heard of this happening?

08-06-2009, 05:14 PM	#9 (permalink)
Nikon FM Track Member Join Date: Jan 2009 Location: Snoqualmie WA Posts: 973 Drives: 03 996TT Porsche Rep Power: 607	Same thing has happened to me (many times) while working through back road twisties. I'm just calling it a feature __________________ Buddy Revell: "One man's sooner is another man's later"

08-06-2009, 02:53 PM	#2 (permalink)
dszombiex Base Member Join Date: May 2009 Location: Los Angeles Posts: 230 Drives: 09 370z MB 7AT Rep Power: 374	Well, not quite the same but related to the synchro rev... I have the 7AT. I was under the impression that the synchro rev is only on when the tranny is in sport mode for the auto and I manually downshift. Until a few days ago this has always been the case for me. Well this past weekend when I was coasting downhill in full auto mode with my foot completely off the throttle, the car suddenly revved twice! It was a decent rev too like up to 4k or something. I drive in full auto mode when I'm lazy or during my daily commute to work all the time. Its never gone off in full auto mode before.

08-06-2009, 04:08 PM	#3 (permalink)
speedworks Track Member Join Date: Jan 2009 Location: Boston, MA Posts: 550 Drives: PW purchased 01/09 Rep Power: 18	I've had this happen many times with spirited on/off ramp driving. The car does feel like it accelerates, but I think it is only not braking (by the engine). I am not sure what or why the car does this - but it has done it since I have had it (Jan). It is only noticeable when I am at/near the limits in a turn (at no throttle).

02-22-2010, 02:09 PM	#5 (permalink)
speedworks Track Member Join Date: Jan 2009 Location: Boston, MA Posts: 550 Drives: PW purchased 01/09 Rep Power: 18	UPDATE: Just took it to the dealer, and was able to re-enact the issue with a tech in the car. One thing I didn't think about was putting my foot in the clutch when it happens. He suggested it, and what do you know, the car went to 4500 rpm and maintained that rpm through the turn (or until I touched the brake or the turn straightened out). So, it was definately maintaining a throttle. Those with this issue should try the same thing. Anyway, the car is in their hands now; and hopefully they call with a option/solution.

02-22-2010, 02:39 PM	#6 (permalink)
Premo34WV Base Member Join Date: Jun 2009 Location: Morgantown, W.Virginia Posts: 68 Drives: PW '09 370z Sp. 6mt Rep Power: 16	glad to hear this was reenacted with the dealer present. Please update us as this is still happening to me. And i agree it only happens at the "sweet spot" of the gear.

02-23-2010, 06:38 PM	#7 (permalink)
speedworks Track Member Join Date: Jan 2009 Location: Boston, MA Posts: 550 Drives: PW purchased 01/09 Rep Power: 18	Quick update: They couldn't find any obvious issue to cause the problem (checked all wiring and sensors, and found nothing). They have a call into Engineering, and are awaiting an answer of what to do next - they will have the car for a few more days. Its supposed to rain around here the rest of the week, so no biggie for me. I also put in a complaint on the PW sideskirts not being a perfect paint fit (like all of them). Again, they will be reviewed by a corp representative when they are back in town (the run around on that one).

08-06-2009, 04:21 PM	#8 (permalink)
noodles Base Member Join Date: May 2009 Location: SoCali Posts: 61 Drives: Mazda (for now) Rep Power: 16	i have heard of this before and more then likely what causes it is the that the rev match is designed so that when you downshift your going to be right back on the gas so it anticipates this and does it for you.

08-07-2009, 01:27 AM	#11 (permalink)
shabarivas A True Z Fanatic Join Date: Apr 2009 Location: Sacramento, CA Posts: 2,188 Drives: 370z MB 6mt Rep Power: 914	Maybe the VVEL was throwing the ECU off.. interesting... lol my downshifts rarely end up near 4k

02-20-2010, 07:58 AM	#12 (permalink)
speedworks Track Member Join Date: Jan 2009 Location: Boston, MA Posts: 550 Drives: PW purchased 01/09 Rep Power: 18	Had to bring this back alive. After driving this car for over a year, I notice it a lot more, and have the ability to recreate it. Anytime I am on a long on/off ramp from a highway, and have a good speed going, and lift off the gas (to hopefully let the car decelerate), the car maintains the speed. Being close to the edge of comfort, it does make me a little nervous, as it is close to the edge of a slipping (and I am prepared to countersteer). So there are 2 inputs, good amount of steering input, and g-forces - it is either condition (or a combo of them) that creates this problem. Anyone else out there have this issue and have you had more time to diagnose it? I am at the point now that I am going to test it around my dealership, so that when I take it in (in the next week or 2) I can show them. I would suspect those that do DEs would feel this (if it was common), on long sweeping turns (which is the only time I feel it). I also notice that it will start to decelerate once the long sweeping turn straightens out (less g force and steering input), or I slightly touch the brakes. It's actually much easier to recognize it since I have installed the FI exhaust as you don't get the decel gurgle until it goes away. Any others? After all of these Toyota issues, I wonder if Nissan has something similar; these electronic gas pedals concern me.

02-20-2010, 08:57 AM	#15 (permalink)
Pharmacist A True Z Fanatic Join Date: May 2009 Location: Toronto, Ontario Posts: 1,249 Drives: 09 370z Sport 6MT Rep Power: 18	I read that porsche has a feature called engine torque drag control or something like that as part of the porsche stability management program. What it does apparently is that it opens the throttle a bit so that the engine revving down doesn't rev down too quickly and cause too much drag on the rear wheels and break their traction and lead to spinning out. Perhaps the Z stability control has a similar feature?