OBDI or OBDII

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Jul 20, 2004 | 09:52 PM

avtt94

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OBDI or OBDII

I believe some 94 Vettes had OBDII in them.Can anyone tell me how to figure out which one I have?

Thanks

Jul 20, 2004 | 10:46 PM

Red Dwarf

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From: sonoma ca

You are OBD I. You can check by looking at the VECI decal on the left side of the radiator shroud (drivers Side).

Jul 20, 2004 | 10:52 PM

vader86

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94 is OBD I

95 got some of the OBD II equipment, but its not functional. The extra O2s are dummies. So its still OBD I.

96 is OBD II.

Jul 20, 2004 | 11:04 PM

wildman378

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Is the OBD II any better? I keep hearing bad things about it but I guess it's better somehow. What differences does the OBD II have over the I?

Jul 21, 2004 | 12:07 AM

bogus

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Quote:

Originally Posted by wildman378

Is the OBD II any better? I keep hearing bad things about it but I guess it's better somehow. What differences does the OBD II have over the I?

OBDII is "better" to a degree. It does make tuning a bit of a pain... or can... But in the GM lines, tuning is not as severly effected as it is with other brands.

The major difference is intellegence. It has more sensors and can assume things based on the input from those sensors.

For example, it has 2 O2 sensors on each bank, the 2nd reads the downstream exhaust. The idea is that now the computer knows how well the cats are working, which allows for more tuning of the fuel and timing.

Jul 21, 2004 | 01:49 AM

VenkmanP

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Quote:

Originally Posted by vader86

94 is OBD I

95 got some of the OBD II equipment, but its not functional. The extra O2s are dummies. So its still OBD I.

96 is OBD II.

94 also has some of the OBDII equipment - OBDII diagnostic plug and an extra O2 sensor.

Are you serious that the rear O2 on 95 (and thus 94) is a dummy? As penny pinching as GM is I have trouble believing it's just there for looks.

[edit]
A brief Google search indicates that the switches to SFI and EEPROM are also OBD-II driven.
[/edit]

Last edited by VenkmanP; Jul 21, 2004 at 01:57 AM.

Jul 21, 2004 | 02:08 AM

wildman378

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I can't see that either just having the extra 02's there for NOTHING...hmm

Jul 21, 2004 | 05:08 AM

Mike_88Z51

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From: Sacramento, CA Money can't buy happiness - but it's more comfortable to cry in a Corvette than a Yugo.

steve9899 is correct, "94 also has some of the OBDII equipment - OBDII diagnostic plug and an extra O2 sensor."

Red Dwarf is "probably" correct about your 94 being OBD1 since the number of OBD2 94s was extremely small. He is absolutely correct that your true answer is found on the emissions control sticker on the radiator.

OBD2 is far superior to OBD1 in my book. Some don't like it due to the additional complexity, but some people like carburators over fuel injection. As mentioned the powertrain computers are more sophisticated and better in general. As OBD2 matured there was greater ability to control the computer while driving. Bi-directional control of relays and system components allows significantly greater control of the diagnostics aspect. The number of parameters in a generic OBD2 PCM is approx 92. In my OBD1 Vette the max parameters is 42. Diagnostic Trouble Codes are cleared in my OBD1 car by disconnecting the battery. With OBD2 you send a signal from a scan tool and the code is cleared.