Question for Automatic Z Owners

[SIKHRYDE]

Hey Everyone,

My Z was involved in an accident and I just got it back from the shop.... everything looks good but I noticed something and want to know if this is "norm"

Prior to the accident when I put the Z in manual mode, lets say I was in 3rd gear and I am approaching a stop sign, the car would go from 3, to 2, to 1 until I stopped.

Between each gear, the RPM would like rev a little bit and it almost felt as if the car was self breaking (like there was this force - lol I know this is going to be hard to describe but hopefully you know what I am talking about).

Now my car goes from 3...to 2.... to 1.... and there is none of that. Its like you cant even tell at all. There is not that little rev that happens nor does it feel like the car is breaking on its own.....

I tried doing this breaking hard, breaking slowly, and even just letting the car come to its stop on its own - and it doesn't happen....

Thoughts?

P.S. If you want to see how my Z looked like all banged up (it was pretty bad) you can check the link below - it has all the pictures and stuff during the whole time I was getting it fixed.

Smashed my Z

[Tazicon]

My car would down shift its self if you went just too slow. I normally down shifted far before it got to that point working it as an engine brake. I never remember it rev matching when coming to a stop and letting it shift it's self.

[wstar]

I think what he means is that the gears are changing when they should, but he doesn't hear it rev-matching (blipping throttle) for the downshifts, and doesn't feel the engine-braking effect from it.

Both are pretty subtle if you're just coasting down to a stoplight on the brakes and letting it downshift for you. Have you tried downshifting aggressively in manual-mode on your own? For example, get up around 60mph in Manual mode in 4th gear, and then click for downshift to 3rd. The engine revs should blip up substantially, and if you then let off the gas pedal completely, you should feel the engine-braking slow the car substantially as well (a lot more than the gradual slowdown you'd feel coasting in neutral at that speed).

The 7AT is a complex beast with hundreds of precision parts. It wouldn't be all that surprising if something in there was damaged in a major impact.

[Silly Rabbit]

Doesn't sound right. Sync Rev should be revving the engine to match when you down shift. Hopefully it's something not connected or a simple.

[SIKHRYDE]

Just to clarify I am not downshifting.... I am letting the car downshift on its own (when it is slowing down).

[SouthArk370Z]

Originally Posted by SIKHRYDE

Just to clarify I am not downshifting.... I am letting the car downshift on its own (when it is slowing down).

Shouldn't make any difference. When the transmission downshifts in either mode you should get the throttle blip and feel some engine-braking (although engine-braking can be amazingly light for such high compression).

First thing I'd do is check and make sure all the connectors going in/out of the transmission are plugged in tight. And anything else that might have gotten knocked loose in the crash or during repairs.

If that didn't fix things, I'd look at the FSM to see if I could figure out what might be causing the problem and start checking the things I could. I'd look at the throttle blip circuit first. Could be the torque convertor is not locking/unlocking properly.

But I'm no expert. It may require taking to a dealer for some CONSULT time.

[wstar]

You'd think he'd have a CEL if any of the connectors are disconnected, though. (and again - try downshifting for yourself instead of letting the car do it. The car does it at very low revs with weak blips+braking. A manual downshift should show the problem much more clearly (or not)).

[1slow370]

does your cruise control still work fine? the two systems are tied together fairly closely

[N0SL3N]

I don't think there is anything wrong. In order to downshift the transmission has to increase revs. I would try manual downshifting and see if you still get the engine braking effect. Also these transmission 'adapt' to your driving style to maybe try driving aggressively and the some aggressive braking.

[SouthArk370Z]

Originally Posted by wstar

You'd think he'd have a CEL if any of the connectors are disconnected, though. ...

Good point. I don't think no-CEL eliminates the connectors but it moves them down the list of possibilities. I agree that trying Manual Mode would be the best first step. It may be a problem of perception.

[1slow370]

the cel light isnt triggered for most bcm related connections so it could be a loose connector and you wouldnt know unless youre code reader can check bcm codes (consult,cipher, some of the high end snap on units)

[tonybell_57]

When I let the car automatically downshift, there is no rev-matching. When I manually downshift, there is.