8 speed issue?

[bassheadhemi]

Ok the other day I was following traffic in the right lane and the moron in front of me slammed the brake to turn in a gas station (no indicator of course). I was far enough that I was able to slow down, but then I saw a car behind me coming way to fast for the distance he had so I floored it. FYI , I need to mention that I always disable trac when it's nice out and it was a very nice day.

What happened next is weird. The truck was probably in second gear when I floored it, so it downshifted to first and then it rev up (little wheel spin) but before shifting back to 2nd engine had no more power (like when trac engage). The truck stayed in 1st and wouldn't shift or go over 4000rpm after that, so I set it to neutral, then back to drive and all was good again.

So last night I went to and industrial park and found a long stretch of deserted road to try to replicate what happened. With trac off, I went up to roughly 20 mph, then slammed the brake to slow down to around 4-5 mph and then floor it again. Same thing happened and no light flashing or turning on on the dash, but cruise did turned off.

So I tried from a dead stop and floored it, well I was able to do nice burnout without any issue. Trac light flashed on a couple attempts when going sideways, but the engine never choked. After multiple attempts , it only did this when it downshifted from 2nd to 1st on WOT and IMO it's probably just a builtin protection to prevent damage since the cruise turned off, but I'm curious to know if it happened to others.

 

[Kotta390]

I've never had anything like that happen before but ONCE I had the truck in 3rd gear at 40mph (when I still had 3.21s) and was trying to see for whatever reason how slow I could go before it would downshift to 2nd gear. I did this and it slammed into 2nd gear and I got a light on the dash saying service trans. It went into a limp mode and the dash started flashing and it took my truck to turn off and on to get it back. The code it threw was some kind of over rev code for the trans. Hasn't happened again.

 

[AustinB]

but then I saw a car behind me coming way to fast for the distance he had so I floored it..

This is where you and I differ. You see possible damage to you truck, I see a brand new off road bumper and maybe some cool tail lights.


IMO

 

[Rupert]

P0219?...Engine ovespeed

ben there done that...Hemifever tune...button shifting...revs came up way fast and limp mode, truck wouldn't shift into park etc...until I stopped it and did a key cycle.
scary stuff.

Sean said that should not have happened.

All I can say is I wasn't at WOT, I was trying to learn how the rev limiter worked ( setting) with the tune as compared to the stock 6k.
I learned the tranny prefers WOT to steady increase and wheel spin ...Oh , and I forgot to turn traction control off..duh.

 

[Hemi450hp]

How much gas do you have in the tank? Any chance the hard stop is just pushing all the fuel to the front of the tank and making it surge like that? I can see this being possible if you are low on fuel.

 

[bassheadhemi]

This is where you and I differ. You see possible damage to you truck, I see a brand new off road bumper and maybe some cool tail lights.


IMO

Yeah I used to be like that, but after over 10 claims (I wasn't at fault) in the past years I got tired of all the trouble... I also drive a bike now, so it's a good thing to move out of a possible collision.

But I have to admit that an off-road bumper would have been nice

 

[bassheadhemi]

P0219?...Engine ovespeed

ben there done that...Hemifever tune...button shifting...revs came up way fast and limp mode, truck wouldn't shift into park etc...until I stopped it and did a key cycle.
scary stuff.

Sean said that should not have happened.

All I can say is I wasn't at WOT, I was trying to learn how the rev limiter worked ( setting) with the tune as compared to the stock 6k.
I learned the tranny prefers WOT to steady increase and wheel spin ...Oh , and I forgot to turn traction control off..duh.

yeah, but in my case there was no code and only putting it to neutral and back to drive fixed it.

How much gas do you have in the tank? Any chance the hard stop is just pushing all the fuel to the front of the tank and making it surge like that? I can see this being possible if you are low on fuel.

Tank was 3/4 full, is the pump pickup at the back of the tank?

 

[GP4L]

IIRC, the fuel sending unit/pickup is midtank, slightly rear biased. 3/4 full, I highly doubt the pump picked up air and fuel starved the engine. You probably (for lack of better words) tricked the ECU and made it freak out.

I can't even tell you how many times a friend of mine, who happens to be a complete psycho behind the wheel, has initiated "limp mode" or blown up transmissions for intentionally doing what you accidentally did. (hard brakes to a near stop, then immediately snapping the throttle wide open). And he's not doing that with a nearly 400hp V8 in front of the transmission... he's doing in a Honda odyssey.

 

[Ak47bravo]

I have never had an issue like that but I did have the following issue in my 14' Lonestar 8 speed:



Several times when getting on the highway I would be at moderate acceleration, then I would go WOT and the truck would do an extremely abrupt downshift. I mean, tires would chirp (and not because they are breaking loose due to high torque, but rather the wheels playing catch up to engine rpm.... I.E. if you were in a manual car and downshifted from 3rd into 2nd and just dumped the clutch without rev matching. The car would jerk, possibly even chirp the tires).

I also noticed at stops, that right as the truck stopped the vehicle would have a slight lurch forward.