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93 PCM Timing tables.

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Old 09-13-2006, 01:50 AM
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Default 93 PCM Timing tables.

I know a huge tuning part of the LSx chips is the timing and timing retardation tables. They're very conservative when IAT numbers rise as well. Obviously any of the Series I and II do this as well, but probably not to quite the same extent.

MY question is what is the behavior (specifically 1993 in my case) of hte PCM when the IAT sensor is unplugged? My laptop never worked well with the DIY ALDL cable, so i have no way of data logging myself at the moment to check. Also what'* the threshold, i want to say 60* F..

I did pull it and put in mid grade (same price in town as 87) and it doesn't lose power after lots of in town driving like it did before. Obviously there are some risks, but the weather has been below 60 for the past few days so i thought i'd give it a shot.
Old 09-13-2006, 07:24 AM
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As you mentioned, I believe the default is 60F, however the PCM will adjust for overly rich fuel trims due to thinking it is cold and adding fuel. You may still retain the timing or it may take longer to learn.
Old 09-13-2006, 08:00 AM
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Guess you kinda missed my Happy Box, huh?

http://www.bonnevilleclub.com/forum/...ight=happy+box
Old 09-13-2006, 01:05 PM
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So after reading that, OBD II car'* realize the IAT trick because of the MAP sensor, however the OBD I does not have one, so timing is SOLELY on IAT readings? Only fueling/ A/F ratio will be affteced by the o2?

So if my PCM is like Don'* 95 (they are both OBD I Based..) then i'm running full timing without the IAT sensor in?

Originally Posted by Boosty
I believe the default is 60F, however the PCM will adjust for overly rich fuel trims due to thinking it is cold and adding fuel.
I think the A/F will balance out, like I said it was around 60* anyways the last few days, but it is warming up. Maybe it'll learn through that?
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