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Hard shifts and stuttering at highway speeds

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Old 08-01-2015, 09:30 AM
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Motoboat
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Hard shifts and stuttering at highway speeds

So I figured I'd post about this and update it as i make progress. I have searched and haven't found anyone that has had this exact problem yet with the 7at.

I just took a family trip to NC and on the drive back the car was acting pretty strange. We took interstate 81 and there are definitely some hills and it was pretty hot out. I started getting some really hard shifts when I would go to accelerate, every once in a while it would slam into gear. This would only happen in th higher gears, usually 60+ mph, 1-4 seems to shift fine, if we pulled off at a rest stop driving around town it was fine.

Another thing that was happening during the trip was when going up a hill the car would shake occasionally and kind of stutter. Almost like it wanted to shift or it was stalling. The RPMs stayed constant and didn't fluctuate at all when this would happen. No check engine lights or stored codes when I got home.

If I stopped and let the car cool down, it seemed to help. Manually shifting while going uphill seemed to help too.

I scheduled an appointment with the dealer to take a look, and its due for 60k service soon so I'll update once I know more. It's a 2011 X with 58k, maybe the heat, hills and trans fluid at the end of its service life are all contributing factors.
Old 08-01-2015, 08:27 PM
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slowbird
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Hmmm...maybe the 7AT isn't as maintenance free as we'd like?
Old 08-02-2015, 12:33 AM
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Epiphany
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That sounds more like torque converter than transmission. Having lockup issues maybe?
Old 08-09-2015, 01:06 AM
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So took it to the dealer Wednesday, 60k service performed on the drive train. They couldn't get it to reproduce the problem and the fluid looked fine to them. They said it looked like it should for the mileage with no metal apparent. Tough to trouble shot a problem if they cant get it to happen.

So tonight on my drive home, about 30 min into the drive it starts to act up again...No codes, no SES. So, i guess ill see how it goes, maybe i can get it into the dealer and actually show them, or if not, just hope the trans explodes while still under warranty.
Old 08-28-2015, 09:41 AM
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Update!!!

So, this past weekend I started pulling some of my engine mods to see if any of them could be causing or exacerbating the issues. I really didn't want to take it back to the dealer without narrowing it down some more and making sure I eliminated all possibilities. My procrastination was due to my dread of pulling off the cats again. They were such a bitch to do the first time. Anyone who has done this themselves will understand.

Well, they actually came off pretty easy, i think all that anti-seize i used really really helped. Also the second time around there was a lot less trial and error. anyway, this is what i found...



Bad cat.
You can see how its all just falling apart in there. this was on the drivers side. Its funny bacause when i got it tuned this side was running a little lean. they suspected i had an exhaust leak on that side somewhere.

The passenger side, is nowhere near as bad, but you can tell that the material is starting to fail.

Once i get the oem gaskets in, ill be putting the stock casts back on, but wow. I hope this is the fix, i cant believe how bad that looks. But that is what i get for buying a used pair of HFC. Lesson learned.
Old 08-28-2015, 10:23 AM
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ANMVQ
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Sounds like that might be the issue, What cats where these, how old ? Glad you figured this out. I'm betting on this was the issue
Old 08-28-2015, 10:52 AM
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I had about 15-16k on them. Before that? I should ask you, bought them off you.

I wonder if most of the HFC makers use the same manufacturer for the cat canister itself. Maybe it was a bad batch? I havent heard of others with this issue.
Old 08-28-2015, 11:15 AM
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Originally Posted by Motoboat
I had about 15-16k on them. Before that? I should ask you, bought them off you.

I wonder if most of the HFC makers use the same manufacturer for the cat canister itself. Maybe it was a bad batch? I havent heard of others with this issue.
No wonder I was prompted to replie here , LOL I had them on the car for less than 3k miles. So 20k and they blew apart, I bought them new , I wonder what the warranty was from FI and Lance? Sorry man
Old 08-28-2015, 11:24 AM
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no worries, **** happens. I doubt there is any warranty since im not the original purchaser. im just gonna throw the stock cats back on, maybe once i get this all sorted out ill pick up some Z1 or berks. I wouldnt mind getting one with the extra support bracket.
Old 08-28-2015, 11:38 AM
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I know just feel bad those frincken things were brand new. I installed them the like 6 weeks later decided to sell the car an took them off. I now have the Z1's very happy with them. Price was great under 400$
Old 08-28-2015, 06:23 PM
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That's awful. cats should last a hell of a lot longer than that.

Good thing it's the cats and not the tranny though
Old 08-28-2015, 09:25 PM
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I was just thinking maybe I could hollow out those cats and run them like that...hmmmm
Old 09-02-2015, 05:06 PM
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Got home from work early and installed my stock cats. Took it for a spirited drive through the hills and drove into work today. No issues. Crossing my fingers, I can understand the stuttering being gone, but why the hard shifts before I don't know. I'll update after some miles.
Old 09-03-2015, 07:36 AM
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Rochester
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I was always under the impression that catalyst material only breaks down when you're running rich, allowing non-combusted gas to ignite inside the cats. Over time, the broken material becomes blockage, further exasperating the problem.

Yes? No? IDK... not an engineer. But 20K on a set of cats seems just wrong.

Last edited by Rochester; 09-03-2015 at 07:57 AM.
Old 09-03-2015, 09:38 AM
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Originally Posted by Rochester
I was always under the impression that catalyst material only breaks down when you're running rich, allowing non-combusted gas to ignite inside the cats. Over time, the broken material becomes blockage, further exasperating the problem.

Yes? No? IDK... not an engineer. But 20K on a set of cats seems just wrong.
After flashing with the initial tune from Uprev and doing a data log it was running a little rich, and it became worse as the cat failed.

I was running for about 9 months after initial install of the HFCs without a tune, but everything should have been running lean at that point. So I don't "think" that should have caused the issue, there are plenty of people who have done the same with no problems. I don't really know enough though to make a better guess.
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