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TC lockup issues??

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Old 04-19-2004, 12:05 AM
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Default TC lockup issues??

I took my car out tonight for the first highway trip since the converter install. Between 65 and 85mph it seems like the conveter doesn't want to stay locked-up under any acceleration at all. Even with the cruise control set a slight hill would make the converter unlock. The car also didnt like holding one rpm. It seemed like it was pulsing probably 2-300 rpm up some hills (it wasnt enough most of the time for the tach to read it with its lag, but i could hear it and feel a slight surging).

I don't know if this is related or not, but the car also now wants to overheat. It's not real bad, but the "water temp" gauge reads about halfway between 210 and the next mark occasionally. It would jump up then fall back down a minute or two later. The tranny cooler is in front of the radiator, but I also had to atleast temporarily remove the SLP CAI to make room for it, so there's still airflow.
Old 04-19-2004, 10:27 PM
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ttt

anyone?!
Old 04-19-2004, 10:34 PM
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do you have an atap or something to look at ur KR at that time? Normaly when a converter unlocks like that is because you're getting some KR and the tranny unlocks the converter...Also in your case w/the LT header, Ypipe, and dual dual....right at that frequency on the highway it cause a header or something to bang the motor and ur KS's are reading "False Knock" and will unlock the converter.

I'd lay money that you have 1 or the other of those going on. You will have to try and tighten up the exhaust some, or desensitize your KS's....I did that when I put on my Heads and cam....good luck!
Old 04-19-2004, 10:34 PM
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heres a bump for ya...
Old 04-19-2004, 10:41 PM
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It's misfires that will cause a converter to unlock, not knock retard.
Old 04-19-2004, 10:43 PM
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Originally Posted by 2xLS1
It's misfires that will cause a converter to unlock, not knock retard.
Ahhh...so true...so true...my appologies...but I would still check for the misfires on Atap...you might have a bad wire, plug or be arcing for some reason.
Old 04-19-2004, 10:46 PM
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99% of the time after a converter install the problem with lockup is actually a mis-fire condition. You have changed the mass of the rotating assembly and the computer no longer accuratly reflects the actual mis-fires. Editing out the misfire code PO300 does not clear this issue. Its not code related, it looks for so many mis-fire events per cycle and once it hits about 40-50 per 200 cycles, it unlocks the converter. For people with edit, this is pretty easily fixed, but without, its gonna take a custom tune. You can actually watch this in autotap, there is a PID for converter status, and one for Mis-fire count (NOT HISTORY). Log those while you are going down the hiway. If you get a zero misfire count for 2 cycles, it will re-lock the converter, once you hit 40-50 it unlocks.

I was pretty much the first person to document this issue back before edit came out.

Ryan K.
Old 04-19-2004, 11:03 PM
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does it hurt anything to drive it like this? i don't have autotap or anything
Old 04-19-2004, 11:13 PM
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No, it won't hurt anything but your fuel economy.

Ryan K.
Old 04-19-2004, 11:30 PM
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still got 21.5mpg highway... lol, better than running 3rd gear when 4th was slipping (20mpg)

guess i'll add this to my list for the tune when/if i get my cam this summer...




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