OBD1 conversion trouble
Thread Starter
Teching In
Joined: Aug 2006
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OBD1 conversion trouble Hey guys, Im new to the site (as you can tell cuz I messed up my username) and wanted to see if ya'll could help me with a problem. I got a '97 T/A that im trying to do an OBD 1 conversion on. I got the PCM, LT4 knock module and the correct knock sensor. I hooked it all up and it just ran like crap. Well after my tuner spent a little time looking at it he realized the MAF calibrations were off. He changed those and it was idling pretty nice. Well once we started revving it up it started taking out about 22deg of timing and that wasnt even under load. When I drive it it feels like driving a 4cyl. The knock count doesnt even move and it's throwing a code for the knock sensor. I've tested the sensor, wire, and everything else I could think of and we cant figure it out. I've asked everyone around town and they all say normally it just goes in easy and that they dont know either. My tuner is even friends with the guy who wrote LT1 EDIT and he doesnt know either. Im just hoping that someone has maybe ran across this problem before. Any help or suggestions would be appreciated. thanks
Thread Starter
Teching In
Joined: Aug 2006
Posts: 6
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Thanks. I like the guy that does mine and I trust him entirely with my car. He's been in Gm performance mag a couple times with his car and he's pretty well known. I'm just having one of those freak problems. If anyone has any suggestions please let me know. thanks
I didn't write LT1Edit, but I'm the one Moe talked to. I build the cables...
Yes, it's a weird problem. Apparently the OBDII PCM runs just fine. OBD1 PCM doesn't. Even though you set the knock sensor stuff up right. Moe and I put our heads together and we drew a blank. So many of these conversions go off without a hitch.
I don't think it's a tuning / programming issue, I have a suspicion there's something 'different' about your car that the OBD1 computer just doesn't like. Whether it be a MAF sensor, O2 sensor, or *something*... I honestly don't know.
Maybe someone here will chime in. I'm all ears too.
Yes, it's a weird problem. Apparently the OBDII PCM runs just fine. OBD1 PCM doesn't. Even though you set the knock sensor stuff up right. Moe and I put our heads together and we drew a blank. So many of these conversions go off without a hitch.
I don't think it's a tuning / programming issue, I have a suspicion there's something 'different' about your car that the OBD1 computer just doesn't like. Whether it be a MAF sensor, O2 sensor, or *something*... I honestly don't know.
Maybe someone here will chime in. I'm all ears too.
Thread Starter
Teching In
Joined: Aug 2006
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Oh. Sorry bout that. He just told me he talked to the guy that "wrote the book on programming" so thats what I was goin by. I've just been trying to figure this out for about 3 weeks now and its driving me to drink. I just cant find anything wrong with the car that would make it pull all that timing out. I need to see what its doing with the OBDII cuz now it feels like its starting to pull some out with it too. I appreciate the help. Matt
TECH Enthusiast
Joined: Sep 2004
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From: Clarksville,Tn
Are you sure the knock sensor you changed out is the right one? I know they read different resistance between OBD1 and OBD2 and usually all you have to do with an OBD1 conversion instead of changing out the knock sensor is just turn off code 43 and leave the sensor alone. If you don't turn that code off the pcm sees that different resistance reading and thinks the knock sensor is screwed so it throws a code and it automatically pulls out a bunch of timing. It's worth a try to turn off code 43 and see what it does.
What kind of gas are you running?
a bad tank of gas took me 3 good tanks to clear out so the car would run right.
at 100% throttle it would not pull, let out of it to like 75% and it felt like I had just started spraying the car.
a bad tank of gas took me 3 good tanks to clear out so the car would run right.
at 100% throttle it would not pull, let out of it to like 75% and it felt like I had just started spraying the car.
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Thread Starter
Teching In
Joined: Aug 2006
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As for the knock sensor, I've went through like 5 of them to make sure i'm getting one that works. Thank God Autozone keeps taking them back. But ya I got the right part number for a 95 and its still not working. Next time I have the car hooked up I'll def see if he can turn off the code. Thanks for the suggestion. and for the gas, I always use super and I dont think its bad gas cuz I can put my OBDII in and it runs fine. Then I put back in the OBDI and it doesnt wanna run right. Thanks alot tho. Anybody got any more Ideas? Anything could help. thanks
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Verdad Gallardo What are you asking for at AZ when you go in there?
Are you asking for a 95 KS or a 94?
One way to test if it is KS circuit, zero out the KS tables and see if it runs better.
Also, when installing the knock sensor, how tight are you putting it in?
Are you asking for a 95 KS or a 94?
One way to test if it is KS circuit, zero out the KS tables and see if it runs better.
Also, when installing the knock sensor, how tight are you putting it in?
Thread Starter
Teching In
Joined: Aug 2006
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The KS part # is 10456126, which im told is the right one. When I install it I hand tighten it and then I use a wrench and just get it a lil bit tighter. Im not overtightening it tho. Im gonna try deleting code 43 and see how that goes but I wont be able to do it until later next week so i'll let ya'll kno what happens. I appreciate the help and if anyone might have any other ideas just incase please feel free to let me know. thanks again, matt
