4L60E strange shift behaviors
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4L60E strange shift behaviors I have a 79 Firebird with the LS1 and 4L60E from a 2000 Camaro in it. It upshifts to 4th gear at speeds as low as 5-6 MPH, and will not downshift into first unless you come to a complete stop. Even 100% throttle will not allow a downshift to 1st. I also do not know why it upshifts so fast. I have HP tuners and have been through all the shift schedules and there is nothing in the shift schedule to explain this behavior so I assume it is some kind of malfunction mode. It has a new VSS and gets a good clean signal from it.
It will stay in 1st gear if you select manual 1st with the shifter
Anyone ever seen this before?
Thanks, Dave
It will stay in 1st gear if you select manual 1st with the shifter
Anyone ever seen this before?
Thanks, Dave
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Joined: Aug 2010
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From: Ann Arbor, MI
That is indeed a strange behavior, but since the trans will only shift when commanded by the PCM, it is a PCM or tuning problem.
Make sure you are looking at the correct shift tables, IIRC, there is one for Normal mode, Performance mode and Hot mode.
You should be able to figure this out and correct it with HP Tuners. You are welcome to post the tune here.
Make sure you are looking at the correct shift tables, IIRC, there is one for Normal mode, Performance mode and Hot mode.
You should be able to figure this out and correct it with HP Tuners. You are welcome to post the tune here.
Thread Starter
Registered User
Joined: May 2020
Posts: 7
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Thread Starter
Registered User
Joined: May 2020
Posts: 7
Likes: 0
That is indeed a strange behavior, but since the trans will only shift when commanded by the PCM, it is a PCM or tuning problem.
Make sure you are looking at the correct shift tables, IIRC, there is one for Normal mode, Performance mode and Hot mode.
You should be able to figure this out and correct it with HP Tuners. You are welcome to post the tune here.
Make sure you are looking at the correct shift tables, IIRC, there is one for Normal mode, Performance mode and Hot mode.
You should be able to figure this out and correct it with HP Tuners. You are welcome to post the tune here.
Thread Starter
Registered User
Joined: May 2020
Posts: 7
Likes: 0
That is indeed a strange behavior, but since the trans will only shift when commanded by the PCM, it is a PCM or tuning problem.
Make sure you are looking at the correct shift tables, IIRC, there is one for Normal mode, Performance mode and Hot mode.
You should be able to figure this out and correct it with HP Tuners. You are welcome to post the tune here.
Make sure you are looking at the correct shift tables, IIRC, there is one for Normal mode, Performance mode and Hot mode.
You should be able to figure this out and correct it with HP Tuners. You are welcome to post the tune here.
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Verdad Gallardo Moderator
Joined: Aug 2010
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From: Ann Arbor, MI
OK, I downloaded the Beta onto my desktop and can now read your files.
I agree that all your shift tables look OK.
From the logging I see that it has already shifted into 4th by 8mph with 0-4% throttle position. Your speed, TPS, shifter position and commanded gear all seem to be reporting correctly.
At 10:07:15.00 I see that shortly after you go WOT at 20 mph it shifts from 4th into 3rd, but clearly should be shifting down to at least 2nd.
My conclusion, more like a guess, is that either the HPT Beta is writing the wrong shift tables, or the PCM is defective or scrambled.
Do you have an older working tune for this car?
Personally, I would install HPT release version on a laptop, and either write a previous tune or even stock tune into the PCM. (Obviously you might have to make some minimal updates to a stock tune if the engine is modded.)
I agree that all your shift tables look OK.
From the logging I see that it has already shifted into 4th by 8mph with 0-4% throttle position. Your speed, TPS, shifter position and commanded gear all seem to be reporting correctly.
At 10:07:15.00 I see that shortly after you go WOT at 20 mph it shifts from 4th into 3rd, but clearly should be shifting down to at least 2nd.
My conclusion, more like a guess, is that either the HPT Beta is writing the wrong shift tables, or the PCM is defective or scrambled.
Do you have an older working tune for this car?
Personally, I would install HPT release version on a laptop, and either write a previous tune or even stock tune into the PCM. (Obviously you might have to make some minimal updates to a stock tune if the engine is modded.)
Thread Starter
Registered User
Joined: May 2020
Posts: 7
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OK, I downloaded the Beta onto my desktop and can now read your files.
I agree that all your shift tables look OK.
From the logging I see that it has already shifted into 4th by 8mph with 0-4% throttle position. Your speed, TPS, shifter position and commanded gear all seem to be reporting correctly.
At 10:07:15.00 I see that shortly after you go WOT at 20 mph it shifts from 4th into 3rd, but clearly should be shifting down to at least 2nd.
My conclusion, more like a guess, is that either the HPT Beta is writing the wrong shift tables, or the PCM is defective or scrambled.
Do you have an older working tune for this car?
Personally, I would install HPT release version on a laptop, and either write a previous tune or even stock tune into the PCM. (Obviously you might have to make some minimal updates to a stock tune if the engine is modded.)
I agree that all your shift tables look OK.
From the logging I see that it has already shifted into 4th by 8mph with 0-4% throttle position. Your speed, TPS, shifter position and commanded gear all seem to be reporting correctly.
At 10:07:15.00 I see that shortly after you go WOT at 20 mph it shifts from 4th into 3rd, but clearly should be shifting down to at least 2nd.
My conclusion, more like a guess, is that either the HPT Beta is writing the wrong shift tables, or the PCM is defective or scrambled.
Do you have an older working tune for this car?
Personally, I would install HPT release version on a laptop, and either write a previous tune or even stock tune into the PCM. (Obviously you might have to make some minimal updates to a stock tune if the engine is modded.)
On The Tree
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Joined: Aug 2010
Posts: 7,323
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From: Ann Arbor, MI
Next, thank you for your immediate contributions. Impressive catch to notice the corrupted VIN and knowing this indicates a corrupt file.
Not sure if the Trans Revolution/Mile matters because it was reporting a reasonable SAE Speed. However none of us knows exactly what values the PCM uses for various calculations; always best to keep all of them correct.
