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Old 06-06-2016, 09:22 PM   #86
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Join Date: May 2009
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Re: 4L80E & TH400 Tech.

Originally Posted by aggie91 View Post

I have more of a programming question than a mechanical rebuild question for the 4l80e.

The set up is a 5.3 running off a 2000 Silverado PCM. We did a segment swap to change from a 4l60e to the 4l80e. Followed the wiring changes needed as found on

The truck idles fine in park or neutral, but stumbles and dies when you put it in gear. From past experience with a TH350 doing this, it would lead me to believe the convertor is to tight and loading up the engine. Before going to that point and swapping convertors, we have some other thoughts/questions.

When we shift the trans to drive or reverse, the notice the O2 sensors nearly stop working and then it dies. If we add 1-2% throttle, we can keep it running.

How does the electronics of the trans interface with the PCM? Does shifting it to drive electronically effect some part of the tune for the engine? If so, what parts should I look at?

There is a Park/Neutral wire that comes from the Neutral Safety Switch that idles the engine up 100rpm when you shift into any gear other than Park/Neutral, But most swaps dont need it.

Is you IAC motor working?, A stuck IAC will cause this issue because it cannot adjust for load.

Converter Clutch Drag is VERY common on high mileage 4L80E's because the lack of "Lube to Line" bypass on stock units, Is this a rebuilt unit? This usually rears its ugly head when the unit is Hot/At operating temp.

I'm not a Tuner, I wish I was!! Boosted C10, BrewCity, or Hart Rod will know more about that. I take that back....I don't wish I was, My plate is full enough

Originally Posted by boostedc10 View Post
More like how it holds up to my abuse and the twin turbos
Pressure Rise, Pressure Rise, Pressure Rise
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