I was wondering what the difference was with OBDI/II and which is better. I have heard of people converting their II cars to I and claiming less backfire at higher rpm's and was wondering if anybody had done this and could tell me if their car ran any better/gained power.

 

Many people like OBDI better simply because it monitors less sensors and therefore is easier to mod or "trick" when it needs to be. One thing you will find with many that have and OBDII is "random misfires". That has to be the worst problem to find. It might be interesting to see what the LS1 folks are doing with regard to I or II.

 

OBD 2 cars monitor quite a few more sensors...pre and post o2 sensors..misfire monitor...evap emissions...fuel tank pressure....just to name a few...and it does make it more difficult to mod your car...but all of those problems can be solved with LT1 edit. So in my mind...I'd deal with OBD 2 rather than converting it. Many emission stations require 96 and newer cars to plug into their computer...no treadmill. If all your readiness tests aren't available...you fail. OBD 1 cars go on the treadmill, and it's easier to get a sticker on a car that shouldn't really have one, some even resort to writing a separate program just for emission day...then after they get their sticker...flash it back.

 

So the OBDII monitors misfires? So if it monitors the misfires then why have I heard that more OBDII cars backfire than OBDI cars. I don't know, I just wonder if power wise I would benefit from switching my car to ODBI.

 

Here in CA they plug into your ALDL port if you have a 96 or newer car; if you switch to OBDI, you'll fail to communicate and fail the test.

 

If emmisions testing is a concern the OBD2 is easier because they will want it in there at testing time so they can plugin to it. For those of us whop don't have to deal with that stuff and are interested in doing our own datalogging and tweaking of tunes then OBD1 looks better as the software is a fraction the cost. Tunercat of OBD1 is $90 and not VIN locked LT1 Edit for OBD1 is $200 and more like $500 for OBD2 the LT1 Edit being locked to one car unless you pay for additional, and OBD1 even has a free datalogger available it is rather simple and not particularly reliable but it gets us started and the developer deserves a thank you for that especially at the price. Tunercat is said to be testing OBD2 software it is said to be similar in price to the LT1 Edit for OBD2 though but not VIN locked.
I like the OBD1 swap but can admit it is not the right choice for everyone, some of it also depends on how much you plan to mod the car, if the engine is to remain stockish then maybe run the OBD1 swap 50weeks of the year and just put the OBD2 in for a week or two before the plugin smog test.

 

Emmisions is not really a big concern, because they really don't give thorough inspections. Thats one nice thing about Texas. How hard is it to change out the computer? Is it just unbolting it and pluggin in the other one, or is there a lot of tuning that must be done afterwards?

 

The OBDI PCM is an electronically faster PCM - it has less to do. For this reason, simply swapping the PCM's on my car cleared up a nagging high-end miss problem we could not eliminate through tuning the OBDII. It worked for me, and others who have big heads/cam combinations on OBDII cars.