V6 owners .. question.

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Mandrake
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Post by Mandrake »

Chris570 wrote: 5-8 seconds??? does it slowly pickup and then go or is it nothing, then it wakes up?
I went out and tried to capture a video of what I'm describing, Murphys law says it didn't want to play up, at first anyway, just before I got home again though it did play up just a little, as below:



It happens at 38 seconds, I'm going up a slight incline and have slowed right down for someone about to turn but I'm still in 2nd gear, then I suddenly accelerate about half throttle, I keep the throttle steady at half way for 6 seconds, you can see the road speed increasing but the rpm falling. Probably hard to pick up on video although listening to the engine note on headphones might make it more obvious.

It wasn't too bad during the recording, but when it gets really bad the engine rpm drops away without much if any increase in road speed, all with a constant throttle. The torque converter transitioning to lockup is what is triggering it due to the reduction in slip, but the problem is that the engine doesn't have the torque to hold the rpm steady and accelerate the car, instead the car stays at the same speed and just pulls the engine rpm down...

Surely not normal ? Remember too that that 6 second period was nearly half throttle in 2nd gear - and should have been far greater acceleration than that.

PS sorry for hijacking you thread Mike. :oops:
Simon

1997 Xantia S1 3.0 V6 Auto Exclusive in Silex Grey
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Re: V6 owners .. question.

Post by Stempy »

Count to three then give it a damn good thrashing......
It infuriates me to be wrong when I know I'm right

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Re: V6 owners .. question.

Post by Chris570 »

if only the xantias could give us some nice graphs!

now, don't bit my head off, but mine does that sort of thing. In mine it's where the gearbox gets confused as to what I want. Now, if you were to open the throttle right up what would it do? I presume kick down and then go like a rocket? or does it bog down?

Does it ever do it in sport mode?

(you've probably covered this in your thread but I can't remember)
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Re: V6 owners .. question.

Post by Mandrake »

If I was to push the throttle right down it would kick down to 1st and go like a rocket of course, and make a big scene about it. (Kicking down to 1st full throttle is something I try to avoid...) If I push the throttle most of the way down in that situation so that it doesn't kick down it does 5/8 of bugger all, it just stays bogged down...

It doesn't really do it in sport mode because these set of symptoms (bogging, lack of torque) happen at low rpm.

I don't think the gearbox did anything wrong in that period of time or got confused - it stayed in 2nd and transitioned smoothly between TC unlocked and TC locked which is normal when easing off acceleration. (Except I wasn't easing off the throttle, the engine torque was falling off by itself)
Last edited by Mandrake on 16 Jul 2013, 21:39, edited 2 times in total.
Simon

1997 Xantia S1 3.0 V6 Auto Exclusive in Silex Grey
2016 Nissan Leaf Tekna 30kWh in White

2011 Peugeot Ion Full Electric in Silver
1977 G Special 1129cc LHD
1978 CX 2400
1997 Xantia S1 2.0i Auto VSX
1998 Xantia S2 3.0 V6 Auto Exclusive
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Re: V6 owners .. question.

Post by Chris570 »

does it do it if you've recently been partaking in some "spirited" driving?

5-8 seconds is a lot longer than mine but mine does bog down under certain conditions. I get the impression that the mapping of the gearbox behaviors was done after a big french lunch.
2006 C5 HDi 170
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Re: V6 owners .. question.

Post by Mandrake »

The more sporty maps don't suffer quite as much, no. SK1 (old git mode) suffers the worst for bogging, and it tends to fall into that mapping if you do any normal law abiding driving in a 30mph zone for more than a few minutes...but it only suffers worst I think because it holds the engine rpm low where the (not performing normally) engine is lacking performance.

Here's another clip from the same test drive but right at the beginning. The performance is normal(ish) in most of this video:



The first bit up to 50 seconds is downhill so doesn't show us much, from 50 seconds to 1:25 was up hill on a reasonably steep section of road. At 1:15 I slowed down to navigate parked cars then accelerated again in 2nd - this time you can see the engine rpm hold steady as the road speed climbs while the TC transitions to lockup. This is what it should be doing AFAIK, and what it does do when its in one of its good moods. In fact there's nothing really wrong in this video from the first 3 minutes of driving...the other clip was from about 10 minutes later.

This is what I mean by it changing from good to bad in just minutes.
Simon

1997 Xantia S1 3.0 V6 Auto Exclusive in Silex Grey
2016 Nissan Leaf Tekna 30kWh in White

2011 Peugeot Ion Full Electric in Silver
1977 G Special 1129cc LHD
1978 CX 2400
1997 Xantia S1 2.0i Auto VSX
1998 Xantia S2 3.0 V6 Auto Exclusive
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