What would cause truck to defuel on 310?

[O2ShootTheJ]

So I had the 310 beta tune and it would always just kinda die and totally defuel right before it made either the 3-4 or 4-5 shift. I figured that was just b/c it was a beta tune and brushed it off.

I finally updated to the new firmware and got the 310 tune and loaded up the 310 agressive today. First drive, moderate acceleration (Maybe half throttle at most) and it did the same thing, defueled hard. On the beta I had no problems when the converter was locked or if I babied it, haven't really tried with the release version yet.

I know that if it detects the tranny slipping it'll defuel, but i don't feel like it would slip every single time? Is there anything else that could cause this?

I've also noticed that truck seems to shutter or surge on the 275 also.

Thanks

[GC Builder]

Did you do the relearn? I know if i drive mine "normally" for awhile and then decide to jump on it for half or 3/4 throttle, it will fall flat on it's face. Beat on it a little. Works for me. I've always just chalked it up to the way the tranny adapts to the way you drive it.

[O2ShootTheJ]

nah i dont have the tcm so i didnt think you needed to do the relearn

im gonna try the mild 310 tomorrow. Reason I didn't stick with it today was because I had a little ways to drive to go watch the NADM pull (which was pretty cool) so i popped the 275 back in.

[powerhoghp]

Relearn is needed for higher tunes, recommended for all.

[GC Builder]

^^^^^^^^^ Yep!

[dhanna6powerstroke]

I'm not a 6.4 own but I have heard that the 310 tune can almost completely deplete the fuel in the fuel rails at WOT. Also, pressure supplied to the injection pump can drop to 1 PSI. Maybe it's not defueling, just running out of fuel? Just a thought.

[O2ShootTheJ]

I'll watch the Fuel Rail Pressure today but it was only at half throttle so I really don't think i'm losing pressure quite yet. Gonna try to get a air dog thrown on with some other things towards the end of summer.

And I'll see if I can find the relearn process and do it sometime today. Thanks everyone I'll let you know how it turns out

[08stroker250]

You need to do a relearn!

Are you feeling it the defuel from the 2nd shift to the 3rd or after? Its most common to get a tranny slip and defuel with the 2-3 shift, not the 3-5 shift.

[O2ShootTheJ]

It might of been the 2-3. I've been running the 310 mild and its been behaving a lot better. I've done bits and pieces of the relearn but i don't really have anywhere to do it where I can safely do it and not get a ticket. I guess I'll have to keep looking for a spot.

[08stroker250]

The only difference between the 310 mild and aggressive is the tip in. You will probbaly notice that the throttle sensitivity is much greater with the aggressive file. Its not that its a stronger tune....the throttle is just sooo much touchier.