The M

I am close to purchasing a used 958 and have driven a couple of GTS models but today I drove a CTT which felt good except for an odd power pullback during what I think was the first to second shift. Although it might've been second to third - it's all new to me and I couldn't really tell. Anyway, I don't remember the GTSs doing that. Could this be an adaptive shifting software "learning" issue based on the owner's driving habits, or is this a harbinger of something else? I'm guessing that there was about a 3/4 second delay until the power came back in. Ideas?

deilenberger

Without experiencing it - hard to say.

How were you accelerating when this happened? Hard/easy - regular or sport mode?

There have been some transfer case issues, revealed by slippage in 2nd-3rd gear shifts at high power. That's usually described as a lurch under acceleration. Seems more common on the V6 models for some reason - but perhaps just because there are more of them on the road.

It might also be the Porsche PSM cutting power if it detected wheel slippage. Worn tires and wet roads might cause this.

I doubt if it's adaptive shifting learning - but try driving it in sport mode - that allows for higher RPM/torque-load shifts. If there is a slippage problem it will be revealed in sport mode.

Can we assume you are going to have a PPI on the vehicle? Or is it Porsche CPO?

BTW - more details you give - like year/model/etc allow us to give you more intelligent answers.

The M

It's a 2011 Turbo in sport mode. I planted the throttle quickly while rolling at about 5 mph. After a couple of seconds for what I assume was turbo spool time it took off really well. On the up shift it felt like the throttle pulled back quite a bit before resuming after the gear change - in fact, the owner/passenger commented on why I was lifting off the throttle even though I had it planted hard the whole time. On second thought I agree that it's not adaptive transmission issues since it appears that it's an engine power issue. So to all of you CTT owners - do you feel this "power reduction" between gears? It seems so delayed that I can't think that it's normal; but I'm new to the Porsche scene so maybe my expectations are off.

Texas993

No way. With sport mode and hard acceleration it takes off like a screaming banshee. No lurching, no pause. Just crazy launch to big speeds.

sjt0017

I'm having the same exact issue. In all other shifts between sport & non-sport mode, the truck is great. In sport mode between 1st & 2nd gear, there's a long delay between shifts. At a quick glance, the truck hits 7k rpm and halts, waits for the TCU to shift to 2nd. This is basically one full second between shifts but the motor wants to keep pushing.

Did anybody ever figure this out, is this common? I wish we had TCU support as other P cars do, as I feel that it could be a simple remedy with a TCU upgrade!

For reference, 2013 CTT 70k mi, doesn't have PTV/PDCC.

Snipe656

My 2015 S does that from 2-3 but seems like only with a certain amount of heavy throttle, not full throttle but guess more like 3/4 and in regular drive mode. Always happens in a time when trying to quickly get around something and not a time when really paying close enough attention to figure out the exact conditions. It seems like almost a programming issue, like something off right after it shifts into 3. No idea if happens in others, never had it happen in the countless miles I have put on base models but will mention it to dealer whenever it goes back for something else.

St8haus

My 2013 CTT is doing the same thing...for me it is the 1st to 2nd shift, and when I am REALLY on the throttle. "Chokes" out around the 7k mark, pauses then shifts. Told the dealer but they could not replicate it...think I need to take them in the car to show them.

Anyone else? This is bothering me...because otherwise it is a BEAST!

2013 CTT, 40k miles, no PTV/PDCC

CarGuyNVA

Reviving an older thread, but this is exactly what I'm describing in my more recent post here..... https://rennlist.com/forums/cayenne-...ar-anyone.html

Anyone from this older thread ever pursue this further?

deilenberger

Just as a comment - all modern ECU's cut power for an instant when a shift is taking place - it takes the load off the gearset and clutches, and when done right, you can't even feel the shift. It would be interesting to hear if this symptom still exists after a transmission ECU's "learned behavior" was cleared.. if you have an iCarScan it's pretty trivial to do.

CarGuyNVA

This sort of crossed my mind as well as a possibility. I don't have iCarSoft though.

Now today I did one heavy acceleration run with a slight rolling start from 1st gear and the shift to 2nd was fine, right before/at redline. No hesitation/bog. The only difference this time is I don't think I had my foot literally pressing the pedal all the way to the carpet, but very close. The times when it's hesitated on the 1-2 shift it literally feels like the fuel cutoff at the rev limiter, and the tach confirmed it was in that region. Manually shifting a bit short of there avoids the problem. And again, sometimes in automatic mode its fine.

So apparently judging from these posts, I'm not the only one that's experienced this. I'm just more curious than anything why it does this sometimes. Not a real big deal. I don't encounter that situation hardly ever anyway. Runs like a champ overall!

St8haus

IMO something is not right, but it seems others are having the same issue. The first time it happened, I though I blew up the Tranny...then it shifted and all was well

CarGuyNVA

When mine's done it, it didn't feel anything like blowing a tranny. Just a brief hesitation between the 1st and 2nd shift at redline. Not all the time either. I'm not real concerned about it, I rarely encounter it anyway. Vehicle runs/performs fine overall.

RAudi Driver

All I know is that the shifts between first and second take a second to engage. That was until I got my car out of the shop the other day. Now the shifting is instantaneous and there is no more time waiting between gears. Weird as the only thing they did was to plug in some electrical plug that was disconnected.

i'm headed to pic up my kid from school. I'll test that theory out this afternoon and report back if it's true or all in my head.

St8haus

Guess I didn't explain properly...since I was flooring it, when it hesitated I thought for a split-second that something was wrong since it would't change to 2nd...so not a blow tranny, but the first time it felt like I did something by flooring it off the line.

Same here, the CTT is a beast and running great, 43k miles and counting!

deilenberger

That should have been iCarScan.. sorry. Changed it in my posting and your quote of my posting. Well worth getting one if you're serious about your Cayenne..