Aldl(obd1) to obd2

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zcylex
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Aldl(obd1) to obd2

Postby zcylex » Fri Feb 21, 2014 11:12 pm

Just wondering if it is possible, i know its not the engine that determines it, but what would be required to say change my 88gt to obd2 aside from a different wiring harness and ecm


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1988 Beretta GT 2.8L V6 - Yeah my Retta is a year older than me! :)
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Rettax3
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Re: Aldl(obd1) to obd2

Postby Rettax3 » Sat Feb 22, 2014 4:53 am

Pretty much what you said, wiring harness and ECM (PCM). '96 is the only OBD2 year for the L-Bodies, so that narrows it down for you, although other 3X00 computers should work. You will also need the injectors that the OBD2 PCM thinks it should be running, and if you are going to keep your 2.8/3-speed auto, the new PCM will be confused as to where its' 4T60E went. You may also have some problems with the tune being a little off, since the 2.8's intake is so restrictive, but the OBD2's MAF should compensate well enough that it won't hurt anything, same for the small displacement change. You will need a heated O2 sensor (or two, since the OBD2 system used both an upstream AND a downstream sensor), the OBD2 MAF, and a three-wire coolant temp sensor, and it will not like the fact that your 2.8 has neither a cam position-sensor nor a hi-res (24x) crank position sensor, so it will be in 'limp' mode all the time. You CAN put the timing-cover and hi-res CKP from a 3X00 with the harmonic balancer with the reluctor ring onto your 2.8, but the power steering pump might need to be shimmed (I needed 10mm spacers on mine) and you will need to figure out a new lower radiator hose as the 3X00 outlet is smaller than the 2.8 MPFI's, and you STILL won't have the cam sensor... There is also some wire that needs to be tapped into, and there would be a tach issue to deal with. Don't you have the digital instruments on your car? They are run by your ECM, so you would have to piggy-back an extra sensor if you wanted to retain your temp gauge, unless you can figure out how to use the feed from the three-wire sensor for both ECMs, and you would lose your tach unless you rigged-up a second circuit for that. You wouldn't need to worry about the oil pressure sending unit for the OBD2 harness, if you let the original sender/harness continue to run your fuel pump.

There is a lot of other specific info on this site about swapped in an OBD2 harness, but trying to make it work with a 2.8MPFI and a 3t40 (TH125C) is not really sensible. Doable though, yes...


1989 SuperCharged 3800 Srs-II (First)Six-Speed GTU
1990 Turbo 3.4 5-Speed T-Type
1990 4.0L 4-Cam 32-Valve V-8 5-Speed Indy GTi (Project)
1990 Stock(!) 3.1 MPFI Auto Indy
1995 LA1/L82 4T60E Z-26
1995 3.4 DOHC Turbo 5-Speed Z-26

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zcylex
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Aldl(obd1) to obd2

Postby zcylex » Sat Feb 22, 2014 11:17 am

Wow! Thats a lot of work! I wouldn't have a problem with having to basically redo the harnesses but i now know the ecm would be in limp mode permanently, so its not an option. I don't have a digital dash (although all of our cluster are digital otherwise we would have a speedo cable. For it to be really analog lol)

So i guess obd2 is a no go for my engine(im not changin/adding camshaft and other sensors to my engine lol) long live obd1 :)


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Rettax3
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Re: Aldl(obd1) to obd2

Postby Rettax3 » Sat Feb 22, 2014 2:25 pm

Nothing wrong with OBD1, except that it doesn't help you out quite as much on the diagnostics. Best part about it though is that your 'code reader' can be a paper-clip, instead of an expensive diagnostic tool that you have to buy AND actually have with you, which is no help if you left it at home in your tool-box while you are out driving and have an engine problem... Good point about the instruments, you smart-alecky kid. :D :beer: But you did know what I meant, so we are okay there. Have you ever thought about becoming a lawyer? :wink:


1989 SuperCharged 3800 Srs-II (First)Six-Speed GTU
1990 Turbo 3.4 5-Speed T-Type
1990 4.0L 4-Cam 32-Valve V-8 5-Speed Indy GTi (Project)
1990 Stock(!) 3.1 MPFI Auto Indy
1995 LA1/L82 4T60E Z-26
1995 3.4 DOHC Turbo 5-Speed Z-26

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zcylex
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Posts: 137
Joined: Sun Sep 15, 2013 2:31 am

Aldl(obd1) to obd2

Postby zcylex » Sat Feb 22, 2014 4:59 pm

I am going to build a datalogger for my obd1 (i actually carry a small obd2 scanner on my DD) so it can help me in those cases.

And no never thought about being a lawyer, tech and cars are my thing. Lol.


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1988 Beretta GT 2.8L V6 - Yeah my Retta is a year older than me! :)
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