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Discussion Starter · #1 ·
so ive decided to go with the lt1 rout since it seems like a pretty strait forward install. my question is what are the pros and cons with using either a obd1 pre 95 motor and trans or a obd2? anything special i have to look out for when doing the install?
 

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The only advantage to the OBD1 setup from a 92-95 engine/pcm is that you have a few more (cheap) choices on programming and data logging software with OBD1.

The 92-93 Corvette and 93 Camaro engines are speed density and don't have a MAF sensor. They also have a computer with a chip. So they tune more like a TPI engine. To tune on the engine/computer, you program a new chip, or convert to a flash programmable chip.

The 94-95 engines have a MAF sensor and the computer is flash programmable - no chips.

The 96-97 engines are OBD2, they have some extra sensors but are otherwise similar to the 94-95 engines. It is possible to run a 96-97 engine with a 94-95 computer.

Part of your decision depends on whether you care about being able to do your own tuning and logging using a laptop and appropriate software and data cable. If you don't want to do that, or don't care about it, there's no reason not to use a 96-97 engine. The other thing is that if you use a 95-97 automatic transmission, you need a 95-97 pcm to control it.

I have a 95 engine for my car, and will use the stock engine harness, with appropriate mods to fit my car. I've purchased the cable, logging s/w, and will use the Tuner Cats s/w to tune and also to disable the VATS, EGR, etc.

Some of the aftermarket engine swap harnesses restrict you to a certain computer and engine configuration.
 

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The ODB1 ('94 version at least) only requires the use of 1 oxygen sensor. This is desirable for ease of installation and the reason I went with a '94 PCM for the '96 LT1 I put in my '83 SS El Camino.
And btw Rick, My '94 PCM controls my '96 4L60E without a problem.

I had my PCM programmed at Fuel Injection Specialties in San Antonio. They built my harness for me too since I didn't get one at all with my LT1.
 

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Discussion Starter · #4 ·
im not to worried about doing tune or anything, i have a 96 impala ss now and i love the lt1. basickly all i would be doing is cam, headers, and 58mm tb and i figured i would send the computer out to pcmforless to have it tuned to what i have. im not building the car for speed so i wont be doing engine mods every week like some people. i just want the ease of a good instalation and trying to get different ideas out there b4 i purchase a caprice or somethign for the engine, trans and computer.
 

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im not to worried about doing tune or anything, i have a 96 impala ss now and i love the lt1. basickly all i would be doing is cam, headers, and 58mm tb and i figured i would send the computer out to pcmforless to have it tuned to what i have. im not building the car for speed so i wont be doing engine mods every week like some people. i just want the ease of a good instalation and trying to get different ideas out there b4 i purchase a caprice or somethign for the engine, trans and computer.
They did the programming on both my '94 ss 6-spped and a stand alone setp for a '95 LT1 and 4l60 trans . They did great work and were fast to deal with. Maybe the OBDII has more custom programming options? I don't know.

Later,

Mike
 

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"And btw Rick, My '94 PCM controls my '96 4L60E without a problem."

The 95-up 4L60E torque converter lockup requires a pulse width modulated signal from the pcm. I'm not recalling the consequences, failure may not be immediate. The problem might be bigger if you mismatch the other direction (early converter/later pcm). The first transmissions requiring that have a big tag that says "PWM" on it, not sure how long they put those stickers on.
 

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The 95-up 4L60E torque converter lockup requires a pulse width modulated signal from the pcm. I'm not recalling the consequences, failure may not be immediate. The problem might be bigger if you mismatch the other direction (early converter/later pcm). The first transmissions requiring that have a big tag that says "PWM" on it, not sure how long they put those stickers on.
I've been running this combo for 12 years and put over 20K miles on it. No problems.
Fuel Injection Specialties didn't mention anything to me on this. They were the ones that recommended I go with the '94 PCM.
 

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Here's a link to an article on the PWM input for the TCC. I didn't have time to read it, but I did see that it discusses failures of some mismatched combinations.http://www.motor.com/magazine/pdfs/062006_07.pdf
Thanks for the link Rick.

If I understand that correctly, the "on" signal from the '94 PCM would be the same as a 100% duty cycle to the PWM TCC solenoid. I think that would mean that the '94 PCM would allow the PWM TCC solenoid to work the same as a non PWM solenoid and cause no problems.

I think you for sure would have problems though if you used a newer PCM on the older tranny just like you said. In that case, you would have a PCM sending a duty cycle percentage signal (pulses) to a TCC solenoid that is only designed for an "all-on" or no signal at all and no in-between.
 

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I think you've probably described it correctly. Thing is, does the later model clutch hit harder than the old style when it gets a full 12 volts? That I don't know.
 

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I think you've probably described it correctly. Thing is, does the later model clutch hit harder than the old style when it gets a full 12 volts? That I don't know.
Good question. And I don't know the true answer.
But, I do have an in-practice answer and some speculation. And that is that I've been doing it for over 20K miles and I don't feel anything out of the ordinary in the car.
Also, there could be circumstances under driving conditions when the newer PCM gives an instant 100% duty cycle to the TCC from 0. I would think it would be designed to tolerate that. The older tranny was.

Anyway, at this point, I am going to say it's OK and not worry about it unless a problem presents itself. I thought about calling FI Specialties but I think I will let it go.

Thanks for making me aware of the issue. Interesting stuff.
 
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