Limp mode - safe mode

[Not_ur_dads_SS]

Ok guys took the truck to the track yesterday, first run out on full tire pressure I staged up to 2200rpm and let her rip. Netted me a 14.043 at 98.2mph. Slower time, higher trap speed. Looked and felt promising the first time, second go at it for the night, lower the rear down to 22psi, staged to 2200rpm hoping to slide into the 13's in stock form, well about the 60' mark it fell on it face :undecided haven't experienced this before in any other vehicle asides for my friends SRT-4 which when in limp mode retards it and limits boost.

So I unhook the battery for about 20-30min and it goes back to normal. Decided to call it a day and just watch the rest of the time after that. Question is what did I do? Or should I ask what did it do? After it fell on its face I took my foot out of it then hit it back down and it only seemed to be getting partial throttle. I am aware this thing has many handicaps from the factory, what happen???

[traumadog]

I know the LS2's do have a "safe mode" with their electronic throttle - and that there had been an issue with the throttle in LS2-powered GTO's going into "safe mode" - which was traced back to the accelerator pedal itself.

Other than that, there may have been something else in the system - including the fact that GM has some tune-limits programmed in for the first 5000 miles (many LS2 cars seemed stronger after this "break-in" period)

[ScarabEpic22]

Sounds like a StabiliTrak/Traction Control problem to me. Were they turned off when you staged?

[Not_ur_dads_SS]

Yea Traction control and Stabilitrak were off. Just think GM probably programed something into these were extra abuse (example: staging to 2200rpm) sets off a mode that prevents you from doing damage to drivetrain components, which is cool but if this is true to what happen to me its also a burden and holding the vehicle back.

[SSkeetobite]

This happened to me in my Grand Prix. It happened when I redlined it trying to avoid a huge ravine in a snow storm. Car was sliding sideways and began to go down. I turned the wheel back toward the freeway and floored it. It worked, but the GP went into limp mode. Had I turned into the skid, I wouldn't have been able to share this wonderful story with you...

I just pulled to the opposite shoulder, turned the car off for a few minutes and restarted it. Everything was fine and I went on my way.

[1BADSS]

You had a high MPH there.Did you have your CAI on?

[TonyGXP]

I know there is a some type of "Abuse" torque management in the ECM/TCM maybe one of the programmers can chime in? sounds like that's what hampered your run..not the regular Torque management that limits the upshifts and high load low rpm (below 3k or so) my GP GXP used to do this if the track was biting real hard and the 255/45/18 Potenza's didn't break loose, it would launch hard and then fall on its face and then go again, had to learn how to launch it differently on good track prep days..I have launched my SS hard as I could and had no problems with that so far with over 25runs to date (my tires are always 22psi at the track)

[Bergie]

Same thing happened to me, ran 15.80! :hissy: WTF! At first I thought it was a fluke, so I made another pass... 15.90!!! DOUBLE :weird: :rolleyes: WTF! I quit after that. On the way home it seemed to pull normal. No idea what the problem was. No idiot lights. No indication of a problem aside from being off 2 full seconds ET in the 1/4 mile. I made sure to disable traction control and stabilicrap before staging.

[Not_ur_dads_SS]

No still didn't have the CAI on it yet, my friend is taking is good old time, he has the pipe and all, just seen to never have time to get it finished. I am considering getting the Vector CAI when I send my ECU/TCU out to get done. The one my buddy is making is making for me is out of what he claims is the equivlent to either 5in or 6in round pipe, its actually oval stock made by Spintech. Its gonna take alot of tinkering to get it right and to fit, considering the top coolent hose. He has the measurements for it just like me can't find the time to do anything.

To properly answer your question, what made the difference was a hunch made by my friend :weird: who I build cars with (look on everything else section for pics of the current project) he told me to take the screen out of the mass air metter and cut the bottom of a breather k&n and stick it in place of where the in box air silencer was. Oddly enough it netted these results. Plus on a spyder AFR monitor it didn't run lean like it does taking the neck down off without a proper tune.