G37 Sedan

G37 torque converter lag

Old Jul 29, 2023 | 05:21 PM
  #1  
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G37 torque converter lag

2013 g37xs 7a

I’m really getting irritated with this transmission and there has to be a fix for it.

In traffic when I let off the gas the rpms drop to idle rather than engine breaking and it’s honestly killing me at this point after driving my buddies car.

going downhill there will be a 1,000 rpm variance between the transmission speed and engine speed. (Watch the video) I let off the gas to coast with the engine compression slowing the car down but it looks and feels like the rpms drop and disengage from the transmission and re engages once I give it gas and rpms reach the speed of the transmission from where it dropped. (Note vehicle speed did not change in the video rpms dropped from 2,500 to 1,500 when I let off and just a tiny bit of gas got it back to 2,500 before I felt the car start throwing power down again)

it makes driving really jerky sometimes and I just can’t stand it anymore and feel like it’s hard on my transmission.

I’ve tried the reset pedal dance with no fix.

Someone help me please!!!
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Old Jul 29, 2023 | 08:00 PM
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If I were to venture a guess, it appears that the torque converter is either not locking up or it is releasing too soon. You should not have that much RPM range at cruising speeds.

You may want to look over this this post as it has some information regarding torque converter behavior. There are several factors that determine when the TC locks up- various sensor data, line pressures, fluid temperature, etc. There appears to be no one definitive fix though many have had good results with getting the TCU updated to the latest firmware.

Perhaps others will have additional input.
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Old Jul 30, 2023 | 03:47 PM
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Ya it’s kind of annoying. I’m traffic I have to keep my foot slightly pressing the accel so it doesn’t do that…..

mines a 2013 so I’m pretty sure all the updates have been done from factory….
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Old Aug 3, 2023 | 11:39 PM
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it seems like it's not locking up




Last edited by zoe infinity; Aug 4, 2023 at 05:31 AM.
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Old Mar 14, 2024 | 11:48 PM
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Transfer case fluid

I think you need new transfer case fluid , I had the same problem , I would let go off the gas pedal and my car would take 2-3 seconds before it moved and even when it moved it was slowwww, Z1 Motorsport sells a transfer case kit , I ya easy to drain and fill , I recommend you buy a pump to transfer the ATF fluid into the transfer case , 30min-1hour job 💪🏽💪🏽
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Old Mar 15, 2024 | 08:54 AM
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Originally Posted by Starbuck393

mines a 2013 so I’m pretty sure all the updates have been done from factory….
Not necessarily. I have a 2012 and I got updates for my trans maybe close to 4 years ago
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Old Mar 18, 2024 | 05:07 PM
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Transfer case fluid video on my YouTube if interested
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Old Mar 20, 2024 | 08:52 AM
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For you to truly determine you need to be in Manual mode.

This gives off vibes as it's in 6th and as you let off it switches into 7th.
Also similar to a converter not locking up on load and locking up once you're off load.
Lastly transfer case issue (dont have much info on this)
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Old Mar 20, 2024 | 01:09 PM
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I think my torque convert has to be replaced bec every morning , every day, after leaving my drive way the car lags going down the street , the rpm’s shoot up and goes back down real fast , I’m that’s not normal, then it does a mean engine/wheel hop , I do let the car warm up 5minutes max
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Old Mar 28, 2024 | 09:45 PM
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Oddly enough my car seems to be the opposite. It provides firm quick shifts when the transmission is cold, but the warmer and longer I drive it, the worse it feels. Often slamming into gear, fluttering, and altogether being unhappy from 15-32mph. It constantly gear hunts and likes to stay at 2k rpm when down low, and will literally thud into gear sometimes. Temps are always fine, I noticed it becomes laggy and unhappy when it gets around 150+ Fahrenheit, say in traffic when you need to switch lanes quickly. But I believe that’s pretty common. Sometimes it likes to drop down to 1k if it’s confident enough.

I had my transmission, transfer case, and both diffs drained and refilled a few thousand miles ago (now sitting at 114k), and it drives me nuts some days. If I remember correctly the first owner had the transmission updated way back when it was new, but I’d be interested in seeing if I had any newer updates. I am tuned so I might have to wipe all that, which I’m not opposed to if it’ll fix my issues.

I’m very confident the fluid levels are fine, the car shifts perfectly when it’s up to speed, it’s only when it’s gear hunting at lower speeds it’s an issue.(Which sucks when half the roads here are 25mph)
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Old Mar 28, 2024 | 10:09 PM
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@yashi you might want to discuss the transmission issues with your tuner as the pressures may not be set correctly.
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Old Mar 29, 2024 | 12:13 AM
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@beefychicken I don’t want to speak on their behalf but I’m pretty sure they never touch anything with the transmission. They’d probably try and convince me there’s nothing they can do tuning wise. So at least it shouldn’t be a tuning issue from my understanding.
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Old Apr 8, 2024 | 11:53 AM
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Originally Posted by yashi
@beefychicken I don’t want to speak on their behalf but I’m pretty sure they never touch anything with the transmission. They’d probably try and convince me there’s nothing they can do tuning wise. So at least it shouldn’t be a tuning issue from my understanding.
Try BG transmission fluid. I was getting bangs and rough shifts too and thought my transmission was going out. Around 70,000 miles I got a trans flush with BG fluid and all the banging and rough shifts went away. Shifts so much smoother than the oem fluid. I find that trans shifts too hard with the OEM fluid especially when the temps get high.
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