Hard down shifting

[Scott Milligan]

Hi folks, I've got the replacement engine installed in my 11 SHO. I just bought the car, it has been lowered, cold air intske, 3 bar map sensor, full aftermarket exhaust and the colder Tstat. It loos like the LMS package but I cant be sure the previous owner didnt have a tuner but I assume the car is tuned. Car has 142k, new engine has 50k.

My issue is ocassional super hard downshift from 3 to 2 or 2 to 1. I have changed the fluid 2 times, verified level. Will the LMS tune (assuming it has one) cause this issue? I bought the car as a project to sell so I was wondering if I had the dealer put on a stock tune if this would fix the issue. I will also have them check for the TSB's on the trans. Other than this issue the trans works fine, no slippage or shuddering. It does shift firm though for sure.

 

[Lostneye]

If it is tuned it most likely will shift noticeably firmer than stock. Check the fluid level and you can try overfilling a 1/2-1 qt over and see of that helps.

You probably know this but the SHO has two MAP sensors, one before the throttle body which is a 3bar stock. The other is on top of the intake manifold and is a 2bar stock. The car will run horribly if the wrong sensor is used without the appropriate tune. If there is a 3bar on top of the intake the car is tuned.

 

[Scott Milligan]

If it is tuned it most likely will shift noticeably firmer than stock. Check the fluid level and you can try overfilling a 1/2-1 qt over and see of that helps.

You probably know this but the SHO has two MAP sensors, one before the throttle body which is a 3bar stock. The other is on top of the intake manifold and is a 2bar stock. The car will run horribly if the wrong sensor is used without the appropriate tune. If there is a 3bar on top of the intake the car is tuned.

Thanks, the car runs great other than the occasional hard down shift. I'm thinking of de tuning it.

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[Lostneye]

If you think it was LMS I would suggest getting in touch and providing the VIN and they should be able to tell you if they tuned it. They do offer a softer shifting tune although I have not used it.

 

[Scott Milligan]

I did call them and they said they didn't use the vin as a reference which surprised me.

 

[Scott Milligan]

I did call them and they said they didn't use the vin as a reference which surprised me.

Car is at dealer, I told them to install stock software to see if that fixes trans issue. They told it might brick my ECU and a bunch of other nm possi bbn le comparability issues. I gave them the 2 bar map sensor and told them to try it. Worst case in suppose I have to go buy a tuner. The previous owner didnt give me the tuner...

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