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4L60 VSS Code 72 cause surging?

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Old Jun 24, 2015 | 09:43 PM
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Default 4L60 VSS Code 72 cause surging?

I know its not a 4L60E, but it is a square wave vice sine wave sensor in my 93 Corvette. I have a code 72, and a fresh rebuild on transmission.. Transmission runs great and pulls through 4th gear behind my 396LT1.
But at part throttle/cruise I get a slight surge. Engine is new, sensors are all new within engine, tuned by good reputable company, never any problems. But now I have this code, can it cause a surge with a 4L60?
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Old Jun 24, 2015 | 10:56 PM
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From: Glenbeulah Wi
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A VSS error can cause surging because the engine does not know that car is moving and so it can effect the IAC s settings and transmission lock-up functions.
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Old Jun 25, 2015 | 01:31 AM
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Originally Posted by krackenvette
I know its not a 4L60E, but it is a square wave vice sine wave sensor in my 93 Corvette. I have a code 72, and a fresh rebuild on transmission.. Transmission runs great and pulls through 4th gear behind my 396LT1.
But at part throttle/cruise I get a slight surge. Engine is new, sensors are all new within engine, tuned by good reputable company, never any problems. But now I have this code, can it cause a surge with a 4L60?
Code 72 on a non E transmission in '93 is a transmission select switch trouble code and has to do with internal VB pressure switches and TCC. Related certainly could be I’d think. ECM might have a problem trying to figure out what gear it's supposed to be in.
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Old Jun 25, 2015 | 05:47 AM
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Originally Posted by WVZR-1
Code 72 on a non E transmission in '93 is a transmission select switch trouble code and has to do with internal VB pressure switches and TCC. Related certainly could be I’d think. ECM might have a problem trying to figure out what gear it's supposed to be in.
Interesting. SO the VSS sensor is not the problem? I need to read my FSM.
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Old Jun 25, 2015 | 06:31 AM
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After reading the above post I went and looked at my tuning software, I do not even have a code 72 listed for a 1993 vette, so I am unsure what problem you are having.
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Old Jun 25, 2015 | 06:34 AM
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Originally Posted by krackenvette
Interesting. SO the VSS sensor is not the problem? I need to read my FSM.
Perhaps a "twisted tweak" in the tune? Is the company close that did the tune? I would think maybe just a Tech1 or appropriate scanner could maybe help here and since the transmission is fresh maybe the first thing to check.

Originally Posted by bjankuski
After reading the above post I went and looked at my tuning software, I do not even have a code 72 listed for a 1993 vette, so I am unsure what problem you are having.
There's driveability procedures for the code even in the '92 FSM I'm quite sure. It wouldn't be in earlier than '92 or later than '93. In '94 with the E transmission the code changed.

Last edited by WVZR-1; Jun 25, 2015 at 06:38 AM.
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Old Jun 25, 2015 | 06:43 AM
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Originally Posted by bjankuski
After reading the above post I went and looked at my tuning software, I do not even have a code 72 listed for a 1993 vette, so I am unsure what problem you are having.
Code 72 is gear selector switch circuit via FSM. TECH 1 is needed for flow chart.
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Old Jun 25, 2015 | 06:47 AM
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Originally Posted by WVZR-1
Perhaps a "twisted tweak" in the tune? Is the company close that did the tune? I would think maybe just a Tech1 or appropriate scanner could maybe help here and since the transmission is fresh maybe the first thing to check.



There's driveability procedures for the code even in the '92 FSM I'm quite sure. It wouldn't be in earlier than '92 or later than '93. In '94 with the E transmission the code changed.
The 93 FSM is stating mostly towards 2-3rd gear open and tcc lock points. Torque converter is locking at 42in 3 and 4th gear. I need to find tcc switch and check my tune when i get home. I did switch tunes but there was no difference. Could mean niether did any torque converter changes?
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Old Jun 25, 2015 | 07:32 AM
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Another symptom is the other day I tried to start it and nothing. I always have Vette on battery gender and voltage was 13.1 with my meter.. if gear selector switch is bad, can it cause this symptom too?
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Old Jun 25, 2015 | 11:56 PM
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Could the "surging" being the locking/unlocking of the TC? Or does it happen at a different speed.

Your Datamaster will tell us a lot. My 93 is set to lock at 48 mph and unlock at 44 mph. Likely not stock as I have tuned it extensively. But if that is the speed range of your surging it might tell us something.

Do you have the ECM file? It is a TunerCat or LT1Edit file?

Note: I just pulled out my Datamaster disc; V 3.x.x from 2000 and Windows 98 Wow! They (Does Steve still own Datamaster?) do have V4 out that will load on a Win 7 x64 computer or even Win 8.1.

Last edited by pkincy; Jun 26, 2015 at 12:51 AM.
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Old Jun 26, 2015 | 05:57 AM
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Originally Posted by pkincy
Could the "surging" being the locking/unlocking of the TC? Or does it happen at a different speed.

Your Datamaster will tell us a lot. My 93 is set to lock at 48 mph and unlock at 44 mph. Likely not stock as I have tuned it extensively. But if that is the speed range of your surging it might tell us something.

Do you have the ECM file? It is a TunerCat or LT1Edit file?

Note: I just pulled out my Datamaster disc; V 3.x.x from 2000 and Windows 98 Wow! They (Does Steve still own Datamaster?) do have V4 out that will load on a Win 7 x64 computer or even Win 8.1.
My Tuner Cat shows TCC lock in high gear is 52 and unlock at 42...Hmm
i need to look into this.
I have tunercat DA2 version AX. Datamaster version 4.01 and using Windows7 64.
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