LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

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Old Apr 7, 2013 | 07:22 PM
  #1  
8996chevy's Avatar
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New Here, Need Help Bad

Bought a 95 z28 that had a 1pc rear main non LT1 engine. No heads or intake. bought a 95 Impala ss motor to put into it. Replaced the cutup harness and now I found out it's has a 97 z28 computer in it. Will this computer work with my 95 OBD1 engine and car, will the flywheel work or do I need an LT1 Flywheel? Thanks
Old Apr 7, 2013 | 10:27 PM
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Re: New Here, Need Help Bad

Assuming the LT1 from the Impala SS does not have a flywheel you will need to find another LT1-specific flywheel as the LT1s are externally balanced. A 2-pc RMS flywheel will not fit.

As for the 97 OBDII computer you'll need a few odds and ends to run the OBDII computer. On the other hand it would probably make more sense to find an OBDI PCM.
Old Apr 7, 2013 | 10:30 PM
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Re: New Here, Need Help Bad

Originally Posted by 8996chevy
Bought a 95 z28 that had a 1pc rear main non LT1 engine. No heads or intake. bought a 95 Impala ss motor to put into it. Replaced the cutup harness and now I found out it's has a 97 z28 computer in it. Will this computer work with my 95 OBD1 engine and car, will the flywheel work or do I need an LT1 Flywheel? Thanks
Can you tell me more about how it's not a LT1? So you got a OBDII computer, flywheel yes. This might help 4th Gen LT1 F-Body Tech Aids

Last edited by redline9570; Apr 8, 2013 at 05:56 AM.
Old Apr 7, 2013 | 11:29 PM
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Re: New Here, Need Help Bad

Originally Posted by redline9570
Can you tell me more about how it's not a LT1? So you got a OBDII computer, flywheel yes. This might help 4th Gen LT1 F-Body Tech Aids
Some additional info here; VWVortex.com - TECH: Differences between OBDI & OBDII heads and blocks
Dude, I don't think that second link to VW/Audi 2.0 engines has anything to do with anything on this forum.
Old Apr 8, 2013 | 05:54 AM
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Re: New Here, Need Help Bad

Originally Posted by shoebox
Dude, I don't think that second link to VW/Audi 2.0 engines has anything to do with anything on this forum.
Dude what you talking about . I like German cars.
While your here though, I can't read the obdI pcm through the obdII port in my 95z. Any ideas as to why, I checked the wires and they all looked good?

Last edited by redline9570; Apr 8, 2013 at 06:02 AM.
Old Apr 8, 2013 | 06:32 AM
  #6  
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Re: New Here, Need Help Bad

Originally Posted by redline9570
Dude what you talking about . I like German cars.
While your here though, I can't read the obdI pcm through the obdII port in my 95z. Any ideas as to why, I checked the wires and they all looked good?
Please don't hijack the man's thread. Post one of your own in the computer/diagnostics forum or search there for possible answers.
Old Apr 8, 2013 | 07:02 AM
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Re: New Here, Need Help Bad

what differences are between obd1 and obd2. I already have a 1 pc rear main seal flywheel, that's why i want to know if it will work with lt1 motor and t56 trans. and pressure plate. does the pcm need to be reprogrammed to a specific car/ vin num.?
Old Apr 8, 2013 | 08:16 AM
  #8  
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Re: New Here, Need Help Bad

Originally Posted by 8996chevy
what differences are between obd1 and obd2. I already have a 1 pc rear main seal flywheel, that's why i want to know if it will work with lt1 motor and t56 trans. and pressure plate. does the pcm need to be reprogrammed to a specific car/ vin num.?
The flywheel needs to be externally balanced with the rotating assembly.

The PCM does not care what VIN is on the car, but the differences between the two are large enough where it is safe to say they are not compatible.
Old Apr 8, 2013 | 04:46 PM
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Re: New Here, Need Help Bad

The 97 PCM will be looking for several things that probably do not exist on the 95 B-Body engine, including the cam position sensor, the EVAP system vacuum switch, after-cat O2 sensors. and possibly an issue with the knock sensor.

The cam position sensor is only there to detect misfires, so you don't need that. Have it programmed out of the PCM. Ditto on the EVAP vacuum switch and the after-cat O2 sensors. Check the knock sensor. An OBD-II PCM needs a 100kOhm knock sensor. The 93-95 F-Bodies used a 4.5kOhm sensor. I don't know what the B-Body engines used in 95. I think they even had two knock sensors, so one of them will not need to be hooked up, or you may need to pull the one out of the driver's side.

There will also be mismatches between the engine harness and the body harness connectors, if you are using a 97 harness in a 95 chassis. Shoebox has a detailed list of the pinouts for various years of the F-Body. If you are using an Impala harness, I have no idea what the compatibility is.
Old Apr 10, 2013 | 03:30 PM
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Re: New Here, Need Help Bad

I wouldnt mess with the computers too much. The main difference betwen obd 1 and 2 is the computer readouts and the amount of sensors on the engine. they are on all cars after 1995, however most 95 F-bodys have the OBD-1 computer with a OBD2 connector. Real pain the but to get any readings on it. Again Shoebox has the pinout (his site has MANY useful pictures and diagrams, use him!) If you need help programming and your a newbie, mail order tunes are the best thing for ya.

http://www.madtuner.com/index.php?pa...mart&Itemid=26

He programmed my Z and i have zero complaints about him. There are several mail order tune places around and they can program out anything that your engine doesnt have on it.
Old Apr 11, 2013 | 03:29 PM
  #11  
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Re: New Here, Need Help Bad

just convert the car to OBD1. It is easier to tune and cheaper
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