I don't have same year vert as you but I had similar issues with limp mode and here's my imput;
Check direction of meth spray make sure maf is not getting sprayed.
If ecm gets over heated due to engine compartment heat soak will go into r/p mode ecm will see a voltage issue.

 

Meth sprays straight across (hits opposite side of pipe)

I took apart the intake, MAF, and throttle body. I cleaned everything thoroughly with electrical cleaner and reinstalled. The throttle body was filthy and the MAF was fairly dirty as well. After everything though no luck. Reduced power and I pulled the codes again. Same ones. Im thinking my next step is replacing the throttle body.

I still find it funny/enjoyable that im putting down (+/-) 650-700hp without being able to go full WOT

 

I would try new TB next as well. Obviously would be cheaper to swap yours out with a buddy or something instead of buying one..

Or you could buy one from Amazon.com and send it back if it doesn't fix the issue

 

OP Did you take my advise and try to see if the blade on the TB is opening all the way by working the gas pedal?

 

I figured the vehicle would have to be running for that and I didnt want to start it with the piping and maf disconnected.

Im taking the car to Bailys sometime next week and they are going to plug it up and do some diagnostic work.

 

Took the car in and logged it while hitting the throttle in neutral. We compared the test to previous logs when we know it was running well on the dyno. We noticed that at full throttle (44 on HP tuners) the throttle plate position is 74 degrees. Previously, it had been closer to its full open position of 90 (88 to be exact).

Inside the TB housing is a set of PLASTIC gears that assist with the opening of the plate at different points. Our theory is that the top gear most likely has a broken tooth and this is causing it to not fully open.

At this point im looking for a new/used working LS2 ThrottleBody to replace the current one. I will then open the "bad" one to see if we are correct on the broke gear theory.

Bunch of thanks to Bailys Hyperformance for spending the time!

 

This was my guess what was happening or the signal position was in error to the ecm. Keep us updated and let us know what you find when you get the old TB apart.

 

Do me a favor and pull your passenger side rail cover and take a photo of your PCV lines, and what you have for oil catch cans.

You should have a back check valve on the PCV line into intake manifold ( PVC valley cover to intake port) so your not blowing boost out of that port under boost, which means that your PVC clean ports out of the valve covers become the dirty side under boost, with the piston blow-by pressure being set to the PCV line on the air filter side of the S/C intake.

Hence if your TB is dirty, that that is coming from the PCV line to the intake side of the S/C out of the valve covers, and the inside of your S/C will be even more filthy than the TB was, since the TB is getting meth washed instead.

Hence on a S/C set up, you really want to run two catch cans, but if you are only running one, then you want it on the clean side to catch the oil out of the valve covers under boost, to the front of the S/C when the motor is under boost.

Go to post 55/56 and see the diagrams that I did for both single and dual can set up's for boost motors to keep the oil out of the intake manifold.
https://www.corvetteforum.com/forums...can-pic-3.html

And I bring this up, since if you MAF/TB is that dirty, God only knows what your 3 bar MAP sensor looks like now as well.

MAP (manifold air pressure) sensor is the one with the red label and may need to be pulled to be cleaned as well.

 

The catch can was installed when the supercharger went on 1500 miles ago. Im pretty confident the filth was the 74k miles put on the vehicle before having it. It was about as dirty as I expected it to be having never been cleaned or running a catch can. I also dont believe I have any lines connected before the SC. I believe that line is route to the atmosphere. I will take a look at your diagram and compare though. Thanks!

 

No worries, and with your stock map being swapped out for a 3 bar map when the S/C was installed, a quick pull and look at your MAP will tell you if the oil mess is old, or new instead.

But to point out, you been spraying meth through the TB and Map for 1500 miles now, so find is strange that the meth itself did not get/ keep the TB and MAF clean instead. Plus, figure when the S/C was installed, they would have cleaned the MAF so they could tune the car correctly to start with.

 

I didn't read threw the entire thread, but if this hasn't been mentioned before the two most common causes I have seen for this is a bad gas pedal (sensor but it comes as one) and or a bad T/B.

If you know anyone near you with a C6 try swapping out the gas pedal, it's only a few bolts. Then next the T/B.

I had a gas pedal sensor fail on me once during a NMCA true street race, I was in first place after the first two passes, it's a best of three average race. That gas pedal failing cost me around 5k.

 

So i installed the beautiful brand new throttle body this evening. Started the car, everything seemed great as far as idle was concerned. As soon as I revved the engine to aprox 90% BOOM... reduced power again. Not taking the TB off to return it right now haha. One positive thing is it made me aware of a small meth leak coming out of the connecting line (im positive its not related to this problem as I dont spray meth when revving at idle).

It looks like im going to now try installing a new pedal? Doug are you pretty familiar with HP tuners and what readings should be getting displayed? Problem between the pedal position and throttle but all the CEL codes pointed to throttle body and when we logged it, the pedal was outputting the same numbers as previous test when we know the engine was running correctly.



Regarding the oil catch can here is a pic.


So coming off the intake it goes into a special valve to not open when under boost, then into the catchcan, and then into the nipple coming from under the intake manifold. Then I have a separate line coming off the valve cover that for all intensive purposes goes into the atmosphere. And as you see the oil fill cap is modified.

When I said the original throttle was filthy I may of been dramatic on it. To me it was dirty but in reality it was probably normal for a vehicle with 74k miles.

 

Send me some logs with every throttle/pedal PID you can find to log and I'll compare it to mine just to see if there's anything obvious. I have an 05 Z51 with ECS kit too.

 

Mine is a 05 z51 as well.

I dont have the logs as they are on my tuners computer...50 miles away

I can remember though if you look at my previous post what was being logged for revving the engine. Ill try and explain below on the numbers..

HP Tuner Log from November when the car put down just under 750hp and was running flawlessly.

At full throttle it would register the pedal at a number 44
The throttle plate was at 88 (degrees)


We ran the test on Tuesday with the car in neutral and me nailing it to WOT.

At full throttle it would register the pedal at a number 44
The throttle plate however hit 74 (degrees, and couldnt seem to get it above that)

This lead us to believe that it was the plate that wasnt fully opening. After installing a brand new TB tonight I think its safe to rule that out. I have a new pedal coming tomorrow (only $25 on amazon after giftcard ) to rule out the pedal (hopefully its the pedal). If that doesnt work I think my next step is replacing the wiring from the pedal to the PCM and from the PCM to the TB.

 

I apologize up front for adding unnecessary chatter to this post, but I do want to say that I am grateful to be part of an enthusiast community where others are so willing to offer their ideas, expertise and experiences to help, what is most often, a total stranger. I wish I could help Spoolin, but you all have quickly surpassed my knowledge! I hope the solution is in the queue!

NMJ

 

Installed the new gas pedal. Same problem :/

Running out of ideas on what this could be. If anything it seemed like with the new pedal there was a delay between hitting the gas and the throttle reaction....

 

Got a log of it happening?

 

I do not. It is idling fine but should I try doing a throttle relearn if there is one? I really dont know what my next step is. Should I try to get the TPMS turned back on? I would be shocked and a little upset if it turns out to be that lol.

Im almost to the point of pulling a wiring diagram and redoing all the connections myself.

LG had mentioned that I potentially need to go to the dealer, pay $100 to have my pcm reflashed and then have it towed to Bailys so they can reload my tune.

I can potentially ask them to email me my logs from the other day so you can compare.

 

I'm no mechanic, but i am a tech guy and i understand this post completely. It sounds like some sort of electrical or software issue to me.

 

Keep in mind that you have two things going on in the TB.

You have a stepper motor that is turning the gears, then you have a sensor that is reading back how far the gears have moved instead.

So it could be that the motor is turning the gears/opening the tb correctly, and even the sensor sending out the correct reading for the movement, but someone where in the sensing wiring back to the ECM, it has a problem with not getting the correct reading for the 88 percent instead, and going to throw codes instead of trying to keep the motor opening the TB more to try to reach the 88 percent instead when you go WOT.

If nothing else, try trace the wires for a pitched wire that is either not able to send back a full voltage reading, or it slightly grounded isntead.