General discussion: Limp Mode, am I in it or not

[ncole]

I want to know what exactly happens in "limp mode"  How much power is cut and how is the power cut?  I have noticed an odd behavior with my 2011 SHO and I don't think it is full blown "limp mode" but don't know what is going on. 

My car's ECM will limit boost to about 5 psi.  Timing doesn't seem to be directly impacted, but the Torque readout for wheel hp and torque is down over 100 each. It shifts normal and will accelerate moderately.  It just feels like a 300 hp heavy car instead of a 400+ hp heavy car. The only way to correct it is to stop the car, put it in park, turn it off, and then back on.  After that "reset" I am back to full power.

This always only happens on my way home from work, not in to work (hotter ambient temps maybe playing a part?)
It is usually after at least 35 miles (I drive about 60 miles one way).
It is only noticeable really at WOT, and there is no discernible moment when it happens.  It is not like I am running it hard and it decides to limit boost, it seems to do it when I am cruising and I don't notice until I demand more power.
I can tell obviously, but nobody else not driving probably would. 
No CEL's.
IAT is usually around ambient because it seems to happen while highway cruising.
I have seen no correlation to gas, sometimes I put ~3-4 gallons of E85, but will often go several fill ups of straight Top Tier 93.

So is this "limp mode?"  I always thought limp mode would be much more drastic cut in power, maybe limited to 2nd or 3rd gear to keep speed down.

 

[ZSHO]

It sounds like its related to boost pressure!!
I would try to rule out the boost reference solenoid as a likely culprit or a sticky waste-gate.
The BOV is another issue to consider but would try to rule that out by checking for any signs of oil present around your BOV.!!
Check your waste-gate hoses to make sure there not split or cracked and fully secured with hose clamps.
How many miles on your SHO? Do you an ESP?  Z

 

[ncole]

I am at 90k miles. Not sure what ESP is, racking my brain to try and figure that out, probably something easy lol. My BOV's are vented to atm. I can check on those other things soon.  I was planning on getting it into the shop since my warranty runs out in 5k miles or so.

 

[ZSHO]

I am at 90k miles. Not sure what ESP is, racking my brain to try and figure that out, probably something easy lol. My BOV's are vented to atm. I can check on those other things soon.  I was planning on getting it into the shop since my warranty runs out in 5k miles or so.

Exactly warranty!!.
Check the waste-gate hoses highlighted in red to make sure they did not pop off and are fully secure. Z
Do you have any pics of the engine bay to share?

 

[ncole]

I am at 90k miles. Not sure what ESP is, racking my brain to try and figure that out, probably something easy lol. My BOV's are vented to atm. I can check on those other things soon.  I was planning on getting it into the shop since my warranty runs out in 5k miles or so.

Exactly warranty.
Check the waste-gate hoses highlighted in red to make sure it did not pop off. Z

Will do, I appreciate it. Does that jive with my intermittent issues though? If it were just disconnected, wouldn't I just be low on boost? This is a solid  4.9 psi threshold it seems my ECM is dictating.  Turn the car of and  back on and I am back at 14+ This is not a one time thing, many times I have seen this, never during the morning drive in though.

In general, are all modern cars this sensitive to heat or is that a turbo issue or pre-ignition issue due to DI etc?

Hmm I see some parts I am missing! Maybe some more go fast parts I need lol!

 

[ZSHO]

There are so many factors that can contribute to the issues your having.
It could also be the Evap purge valve solenoid.
I would also try reverting back to stock tune to see if your issues still persist.
Did you try doing a Kam reset.  ?

I would advise using the warranty before its to late,especially with only 5K left IMHO. Z

 

[ncole]

There are so many factors that can contribute to the issues your having.
It could also be the Evap purge valve solenoid.
I would also try reverting back to stock tune to see if your issues still persist.
Did you try doing a Kam reset.  ?

I would advise using the warranty before its to late,especially with only 5K left IMHO. Z

No, is that something I can do with my LMS tuner?  I am real familiar with that stuff, just followed the instructions when I loaded my tune.  I will be going back to stock with a K&N drop in the stock air box before I take it to the shop though.

 

[SHOdded]

Have you owned this car since new?  Has the car always had this problem while you've owned it, or is this a recent problem?

It is possible the wastegate or BOV have weakened, but it could be a hard limit set by the previous owner in a tune, which should be overriden by the tune YOU have.  Or it could be a loose hose connected to the boost solenoid that gives at 5 psi.  Z has provided solid suggestions.  Now it is a matter of eliminating the possibilities one by one.  The KAM reset sounds appealing as well.

 

[ncole]

Have you owned this car since new?  Has the car always had this problem while you've owned it, or is this a recent problem?

It is possible the wastegate or BOV have weakened, but it could be a hard limit set by the previous owner in a tune, which should be overriden by the tune YOU have.  Or it could be a loose hose connected to the boost solenoid that gives at 5 psi.  Z has provided solid suggestions.  Now it is a matter of eliminating the possibilities one by one.  The KAM reset sounds appealing as well.

I bought it stock @ 52k.  So no previous owner issues.  I drove it a bit on the stock tune. This happened before the tune then seemed to go away and is back again. I think I am going to try the KAM reset first.  It has never failed to fix itself after a restart of the car.

 

[ZSHO]

Kam-reset procedure can be found below.
Best of luck and keep us updated.  Z
http://youtu.be/hZAsoqmqhdM