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Discussion Starter · #1 ·
I just got the car back from it's 22,500 mile service where I also had them do the TechNet service for the hard shifting into reverse (grease the intermediate shaft) and I noticed on the drive home that whenever I lift off the throttle the car bucks quite violently. It seems to make plenty of power and drives very well other than the bucking on decel and some bucking at 2000 - 3000 RPM on light throttle.

Of course I'll be taking it back to the dealer to get it looked at but I'm wondering if any of you might have an idea what they could have done when they did the trans service to cause this?

Thanks.
 

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Re: Bucking on decelleration (mjw930)

Forgot to tighten an engine mount?

Tom.
 

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Discussion Starter · #5 ·
Well, I got it back from the dealership and although the problem is reduced, it's still there. They said one of the shifter cables popped out of it's retainer, that's why it was bucking. That sounded fishy but I took it anyway. The bucking under constant, light throttle in the 2500 - 3000 range is gone but then you let up off the throttle abruptly between 2500 - 3000 the car bucks hard.

To me it feels like one of 3 things

1. Drive train slop / something in the differential
2. Screwed up egas settings (too sensitive)
3. turbo bypass / popoff valve not working. It feels like what happens when there's no bypass and you close the throttle while under boost. It causes the butterflies to slam shut.

I can't for the life of me understand how splitting the trans to lubricate the intermediate shaft could have caused this but it did. Hopefully they don't try to pass this off as "normal". I put 22K miles on this and it wasn't "normal" until last week....

Question for those with a 6M. If you are running at 2500 RPM in 2nd gear and take your foot off the throttle fast does your car buck or simply slow down? Also, if you stab the throttle right after this does it snap you back into your seat?

Thanks.
 

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Re: (mjw930)

Take it back to the dealer - I have a 6M and none of what you describe. Under your scenario question, the car did not buck perse, like you now have, but the removal of the resonator (aka "JRL patented mod") thoroughly smoothed-out the response upon deceleration.

I suspect that none of this is contributing to what you now are experiencing, and as they messed-with the transmission of your car, the problems reside there.

Did they do any TNN's in addition to the trans work? Is your idle RPM @ 800?
 

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Re: (mjw930)

Quote, originally posted by mjw930 »


Question for those with a 6M. If you are running at 2500 RPM in 2nd gear and take your foot off the throttle fast does your car buck or simply slow down? Also, if you stab the throttle right after this does it snap you back into your seat?

Thanks.

It depends on how fast I rev to 2500. If I gun it and let go, then it'll buck. But if it's a smooth and slow acceleration, then it'll slow down.

Maybe it's weather related as well (
) but lately it's been doing it a lot . It's actually more noticeable with the JRL mod.
 

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I suggest when you take it back, you actually take one the of service guys out for a ride to show him whats happening so he knows exactly what you want fixed...this leaves no excuse for it coming back to you with the same condition
 

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Discussion Starter · #9 ·
Re: (phuz)

Quote, originally posted by phuz »
I suggest when you take it back, you actually take one the of service guys out for a ride to show him whats happening so he knows exactly what you want fixed...this leaves no excuse for it coming back to you with the same condition

That's the plan. The service manager isn't trying to pass this off as normal, it was his suggestion that I take the tech for a ride and show him what I'm talking about. He was insisted they would make it right so for now they are dealing with it properly. I'm just pissed then screwed it up.
 

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Discussion Starter · #10 ·
Re: (mike_c70)

Quote, originally posted by mike_c70 »
It depends on how fast I rev to 2500. If I gun it and let go, then it'll buck. But if it's a smooth and slow acceleration, then it'll slow down.

Maybe it's weather related as well (
) but lately it's been doing it a lot . It's actually more noticeable with the JRL mod.

Mine always did that too but I'm talking about constant, light throttle then lift off the gas all the way. It really feels like mechanical slop. I wish I knew all the details on the TNN so I could see what all they did.....
 

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Re: (mjw930)

Quote, originally posted by mjw930 »
Mine always did that too but I'm talking about constant, light throttle then lift off the gas all the way. It really feels like mechanical slop. I wish I knew all the details on the TNN so I could see what all they did.....

In that case, no, mine doesn't do that.
 

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2005 V70R, Midnight Blue, M66
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Re: (mjw930)

Quote, originally posted by mjw930 »
Well, I got it back from the dealership and although the problem is reduced, it's still there. They said one of the shifter cables popped out of it's retainer, that's why it was bucking. That sounded fishy but I took it anyway. The bucking under constant, light throttle in the 2500 - 3000 range is gone but then you let up off the throttle abruptly between 2500 - 3000 the car bucks hard.

To me it feels like one of 3 things

1. Drive train slop / something in the differential
2. Screwed up egas settings (too sensitive)
3. turbo bypass / popoff valve not working. It feels like what happens when there's no bypass and you close the throttle while under boost. It causes the butterflies to slam shut.

I can't for the life of me understand how splitting the trans to lubricate the intermediate shaft could have caused this but it did. Hopefully they don't try to pass this off as "normal". I put 22K miles on this and it wasn't "normal" until last week....

Question for those with a 6M. If you are running at 2500 RPM in 2nd gear and take your foot off the throttle fast does your car buck or simply slow down? Also, if you stab the throttle right after this does it snap you back into your seat?

Thanks.

I suspect the problem is more like your item number 3, however if the problem is now mostly under decelleration, than it could be something as mechanical as a motor mount as has been suggested.

I think I would avoid having anyone work on my car that feels the shifter cables could casue the problems you describe. I do believe they were not properly re-attached as has happened to several people here, but to suggest that they can cause the other symptoms is absurd. Clearly they can cause issues such as jumping out of gear on decelleration, but not what you describe.

When you decellerate suddenly do you hear the excess boost exhasted to atmosphere?
On my 2005 V70R there is a distinct chirp under these conditions, especially at higher RPMS, going from full throttle to no throttle.

Just for the sake of clarity it is the input shaft, as opposed to the intermediate shaft that requires the lubrication. To do the repair the transmission is split from the engine, however the transmission itself is not opened. I am sure that is what you meant. It is the input shaft that the clutch disc rides on and binds from lack of lubrication causing difficult gear engagement.

Since the repair involves major engine bay work I would look for any loose vacuum hoses or electrical connectors.
 

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Discussion Starter · #14 ·
Re: (rogersampson)

Quote, originally posted by rogersampson »
I suspect the problem is more like your item number 3, however if the problem is now mostly under decelleration, than it could be something as mechanical as a motor mount as has been suggested.

I think I would avoid having anyone work on my car that feels the shifter cables could casue the problems you describe. I do believe they were not properly re-attached as has happened to several people here, but to suggest that they can cause the other symptoms is absurd. Clearly they can cause issues such as jumping out of gear on decelleration, but not what you describe.

When you decellerate suddenly do you hear the excess boost exhasted to atmosphere?
On my 2005 V70R there is a distinct chirp under these conditions, especially at higher RPMS, going from full throttle to no throttle.

Just for the sake of clarity it is the input shaft, as opposed to the intermediate shaft that requires the lubrication. To do the repair the transmission is split from the engine, however the transmission itself is not opened. I am sure that is what you meant. It is the input shaft that the clutch disc rides on and binds from lack of lubrication causing difficult gear engagement.

Since the repair involves major engine bay work I would look for any loose vacuum hoses or electrical connectors.

Roger,

Yes, I meant input shaft, not intermediate shaft (which is inside the trans). I suspect something not hooked up too and I agree that the shift cable issue was BS. BUT, I don't have any alternative than to use the local Volvo dealer, I'm not going to drive 100+ miles to service a car under warranty.

They have it back and I took the service manager for a ride and showed them. It really acts like fuel delivery / boost bleed and not driveline slop or motor mount.

BTW, I don't hear anything bleed off when I lift, I think I used to hear that. Is that part vacuum actuated or computer controlled?

Mark
 

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Discussion Starter · #15 ·
Problem solved, Tom nailed it, Bad lower motor mount. They replaced that plus the upper mount because the upper was a bit worse for wear considering the lower had broken.

I think the failure was coincidental to the shifter work, not caused by it but aggravated by the work. Too bad the tech didn't notice it when he did the TNN but I suppose they focus on the work at hand and can't see the forest for the trees.

Cudos to the dealership for taking the time to properly troubleshoot and correct the problem.
 

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Re: (mjw930)

Good news! Do you know which lower mount it was (front rear or trans)? I'm curious because they aren't generally an issue, that's why I suggested they didn't tighten one properly. The upper mount is basically just a stabilizer and they are a common issue since the original 850 - you could replace the stock rubber once a year, so it's not a surprise it needed it too.

Tom.
 
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