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Discussion Starter · #1 ·
I have a 94 wagon with a lightly modded 94z motor and I'm considering converting it to OBD2 for diagnostic purposes. I don't have to worry about emissions So I think it might be legal to do the switch. Anybody have any expierence with this type of conversion? Am I wasting my time thinking about doing it? I just feel that I can get a better view of what the computer is thinking with just generic OBD2 data stream. My intention is to use tunercat to get my spark and fuel curves straightened out and PCMScan for my diagnostic work and data logging. I guess my main question is what kind of problems should I expect to run into? with tunercat you can delete sensors like rear O2's and outputs like the airpump right? I have little expierence with re-programming, but I feel confident enough in what I'm doing that tuning shouldn't be an issue. I just haven't decided if I should stick with the OBD1 in my car and get software that will interface with that as well as diagnostic software for OBD2 cars for side work. I would like to be able to buy only the one cable and two programs. What do you think?
 

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That's a very bad idea. What "Diagnostic purposes" do you hope to achieve? Stay OBD1, get an ALDL cable, and use the programs you suggested for datalogging and tuning.
 

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Discussion Starter · #3 ·
I haven't found software that will interface with the OBD1 computer that I really like yet. Do you know if I could get PCMSCAN to work with the OBD1 ALDL cable provided I configure the pins corectly? I also plan on getting an OBD2 cable and software for side work in my garage. It just seams to me that there is a wide variety of OBD2 diagnostic software whereas whats available for my 94 is quite limited and basic. I haven't yet purchased anything outside of a laptop, so I can't think I've made a mistake yet. Any suggestions as to which path I should take would be helpful.

On a side note, Is there any significant difference in the performance of an OBD1 pcm vs an OBD2 pcm? I;ve heard of people going from OBD2 to OBD1 but I don't understand what advantages that would have. I always thought that OBD2 had more information available to be viewed from a diagnostic standpoint.
 

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Get a cable and performance tune from pcmperformance.com or one of the other vendors. Use Datamaster or Freescan for data logging.
BTW, there is no performance increase and a probable decrease when an F-body engine is installed in a B-body since the F-body engine is designed with a much lighter car. The performance tune may help with that. Good luck.
 

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Discussion Starter · #6 ·
I know there are no performance gains to be had right out of the box but I got the aluminum heads ported and got lt4 springs with roller rockers put in. I plan to go bigger with my converter along with a set of 3.73's. The plan is to try to make up for the low end with more rpm and gear. The main goal is to keep building the engine in my wagon and eventually get a light car for some real go fast action. I want to do all the tuning myself so I know that I can. The laptop I'm going to use for that will also basically turn into a scan tool as well. Thanks for all your help and I should be ordering some cables pretty soon.
 

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Honestly...with newer stuff, I like OBD2...but not with LT1's. LS1's and other newer stuff, have great diagnostics, and are great computers...the OBD2 LT1 computer is a bit of a red-headed stepchild, and doesn't do a whole lot more than the OBD1 LT1 computer...I really don't think the wiring would be worth it...the OBD1 8051 is probably the best OBD1 computer as far as diagnostics (with good reason...it was also the LAST OBD1 computer AND is very similar to it's OBD2 successor).
 

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Discussion Starter · #9 ·
WHat exactly are the main advantages of switching from OBD2 to OBD1 ? Is it mostly for the tuning cost and ease? I figured the OBD2 computer would be faster, but then again considering how long the line lasted it does not suprise me that the later computer is not much better than the earlier.
 

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Yes, OBD-1 PCM is cheaper to tune and diagnose and for a while most PCM tuners had better results with it. It also allows you to remove extra emissions/diagnostics stuff like secondary O2s, CPS, etc.

OBD-1 is slower and has a known VSS runout bug with high stall converters because it cannot keep up with sensor readings. That is probably its biggest negative.
 

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Discussion Starter · #11 ·
So what your saying is an OBD2 pcm will more accurately control the trans? I would see this as being advantaegous, outside the obvious drawback to having to deal with all the emissions diagnostics. Isn't it possible to disable a lot of that stuff in an OBD2 pcm, like secondary o2's and air pump and the like? I was under the impression that is was just as easy to manipulate an OBD2 pcm as an OBD1. There are very few differences in the sensors and the outputs are just about the same as well. I figured the parameters would be almost identical as well. I finally got my TunerC.A.T.S. and Ive already corrected my speedo. I'm getting a feel for what i can do with this stuff. The wagon responds alot better having the speedo right on. It used to shift very early after installing the 3.23's, so it didn't ever feel fast. Also I would like to know if i could plug the Z28pcm I have into my caprice and use the tuner to read the pcm? I would like to get the timing and fuel curves from the camaro computer because I am using the camaro cam (for now), and I believe the timing and fuel curves differ slightly and I would therefore like to importh them into the caprice tune I am using.
 

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It really is a cost thing, software to deal with the OBD2 PCM costs more...you can make the same power with either one, and if you have the issue with the high stall thing...do like me and put a T56 in the car :)

Yes you can plug the Z28 PCM in and read it's file out to compare it if you want...are you running the aluminum Z28 heads too? If you're not, the tune won't be exactly a stock Z28 tune or a stock B-Body tune...you can also just download a stock Z28 tune (they're out there) and avoid swapping anything...they're the same hardware though.
 

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Discussion Starter · #13 ·
I am using the Z28 heads but I had them ported so I will have to adjust the tune accordingly. I plan on going with a cc 306 cam and clear image gen2 try-y's when the money gets in. Any reccomendations on datalogging software? I haven't seen anything that I like yet. I figure there isn't alot out there to work with so I would like to know what software has a good reputation amond b-body tuners. I also want to set up the f-car PCM to use as a spare in my caprice. I figure It would be nice to have a spare. Or maybe even a higher octane tune for a bit more on raceday.
 
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