LT1-LT4 Modifications 1993-97 Gen II Small Block V8

OBDII to OBDI conversion

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Old 02-02-2011, 09:59 PM
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Default OBDII to OBDI conversion

Well wanting to go with OBDI with the new build it seems to be a lot better with tuning and everything. Everything I searched for is for the switch the other way around. Do you just change PCM's or what It just seems like I won't be that easy and there is more to it.
Old 02-02-2011, 10:02 PM
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Which do you have now? I put my 95' engine in a 96' chassis. I used the 96' harness and the 95' obd1 PCM.
I just had extra plugs on the harness for the rear o2's,CPS and other things
Old 02-02-2011, 10:06 PM
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You can use the 96 harness. You'll have some extra plugs (like mentioned above) and you'll need to swap to an OBDI knock sensor.
Old 02-02-2011, 10:06 PM
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I have the OBDII and want to go to OBDI because of the tuning being a lot better.

But that being said with the ports inside of the car probably changed from OBDII to OBDI so would have to do all tuning by PCM being taken out for a mail order tune that or do they have adapters ?
Old 02-02-2011, 10:07 PM
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Originally Posted by Lawhead
I have the OBDII and want to go to OBDI because of the tuning being a lot better.

But that being said with the ports inside of the car probably changed from OBDII to OBDI so would have to do all tuning by PCM being taken out for a mail order tune that or do they have adapters ?
You would need a 95-style interface cable (16 pin D-shape, OBDI).
Old 02-02-2011, 10:08 PM
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Originally Posted by RamAir95TA
You can use the 96 harness. You'll have some extra plugs (like mentioned above) and you'll need to swap to an OBDI knock sensor.
So the PCM is what changed it from OBDI to OBDII ?

I've been thinking of changing the harness like you had posted on before but If I can clean mine up I guess I could keep it
Old 02-02-2011, 10:13 PM
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Originally Posted by Lawhead
So the PCM is what changed it from OBDI to OBDII ?
I don't follow you here...what do you mean? There are two types of PCMs - OBDI and OBDII.

Also make sure you get an OBDI PCM for an auto trans.
Old 02-02-2011, 10:19 PM
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OBDI PCM and a corresponding knock sensor.
Old 02-02-2011, 10:22 PM
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Originally Posted by SS MPSTR
OBDI PCM and a corresponding knock sensor.


Alright I guess I was more or less looking for the parts needed to do it my bad Joe for not being too clear lol but thanks guys 2 more weeks and I'll have the short block
Old 02-02-2011, 11:44 PM
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Originally Posted by Lawhead
Alright I guess I was more or less looking for the parts needed to do it my bad Joe for not being too clear lol but thanks guys 2 more weeks and I'll have the short block
Like said, you need a PCM, the obd1 knock sensor and rewire it for your harness. Then tune it to your car with a cable and tunerpro.

All said and done you should be able to get it all for about $150.
Old 02-02-2011, 11:47 PM
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Doesnt madz28 or madtuner make a swap for this kinda thing?
Old 02-02-2011, 11:49 PM
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Originally Posted by BigBadWhitey
Doesnt madz28 or madtuner make a swap for this kinda thing?
Yes completely plug and play for $250 and it comes with a performance tune too.
Old 02-03-2011, 12:27 AM
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Oh decent, i think im going to go that route!
Old 02-03-2011, 04:43 AM
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http://www.carputing.com/

Originally Posted by LSWHO
Like said, you need a PCM, the obd1 knock sensor and rewire it for your harness. Then tune it to your car with a cable and tunerpro.

All said and done you should be able to get it all for about $150.
There is no rewiring necessary.
Old 02-03-2011, 08:23 AM
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Mine has the resistor in the PCM so I can use my stock knock sensor. Plug and play with no mods to anything else. I can swap back and forth in minutes between my 95 and stock 96 computer.
Old 02-03-2011, 09:05 AM
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http://shbox.com/1/harness_connector_faces.htm

Based on the connectors in the link, I would say you have to rewire. Look at the differences between 95 and 96, specifically on the c220 and c230. I did a 93 to 95 swap and had to rig about 5 wires which were different. I think the same goes for 96 to 95 conversion.
Old 02-03-2011, 09:16 AM
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There is no wiring to change between 95 and 96-97. Everything in my car is original 96 except for the 95 PCM.

Its been that way since I swapped the computer back in 98.
Old 02-03-2011, 11:00 AM
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Originally Posted by LSWHO
Like said, you need a PCM, the obd1 knock sensor and rewire it for your harness. Then tune it to your car with a cable and tunerpro.

All said and done you should be able to get it all for about $150.
Fail. STFU noob
Old 02-03-2011, 11:17 AM
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Originally Posted by SS RRR
There is no rewiring necessary.
Shoebox's site speaks of it.

Is there more than one style that maybe you guys can clue us all in to the different types and their specific needs?

Originally Posted by gregrob
Fail. STFU noob
The only thing fail is your sex life.
Old 02-03-2011, 12:58 PM
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PCM from a 94-95 F or B body, F body Knock Sensor (the one on the block) and Thats it! No rewire needed, Have done this dozens of times. 95's already have an OBD II Port on them..


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