Potential Resolution

I hope im not typing this too soon but after a hard day of testing the vehicle yesterday I believe a resolution was found and it paints an unfortunate picture of what occurred.

Ill start by saying the original problem was something very simple. Very easy to overlook and could be replicated. My vehicle has a speed density tune which basically means I do not need a MAF, however it is still being used to measure IAT. The MAF sensor sits right next to the TB with a coupler separating them. If you look at the MAF you will notice the interior plastic wall that normally is sitting vertically when installed.



It is possible that if you jam the Maf into the coupler and install, it will actually sit 1cm inside the throttle body. Even this doesnt create a problem *until* you get near WOT and the TB plate is getting close to 90 degrees. It was hitting that wall. After the pulley install this MAF was simply installed too close. I dont blame the shop for this as its a poor design in my opinion. Unfortunately though, rather than simply taking a closer look at the vehicle I was told I potentially had a bad TB. I purchased a brand new throttle body and installed it myself (making the same mistake of having the MAF too close). This was where everything went to $h!t though because the brand new TB i purchased directly from AC Delco actually had a problem.

So at this point I have taken off the "bad" throttle body and had a "new" one that in reality wouldn't work. I then entered the rabbit hole fixing everything else never once going back to think of the probability that it was possible to have two bad Throttle bodies.

Thanks to 21st Century getting some time to plug in a few more TBs and do some testing we realized the MAF was the original culprit (Not the TB, pedal assembly, wiring harnesss, Pigtail connector, or PCM/Tune). I installed the original TB yesterday and had modifications made to the MAF sensor.



I installed the setup properly so it wouldn't hit the MAF anyways but this will prevent it in a worse case scenario. I spent the day yesterday in the car trying to recreate the problem and could not. An entire tank of gas and 1/2 tank of meth with no reduced power. So after spending thousands trying to fix it I now am back to the original parts. Im just happy I have a running car and fingers crossed this was the problem.

If I ever see reduced power again its going straight in a ditch

 

Wow that is the first I've read of that...but thanks for closing the thread-perhaps someone else will have this problem!

 

I think I would have never figured that one out!

 

I can also show that the *new* bad throttle body fails at random points (I think it gets worse with temperature). Im looking for the proper driver so I can open it up and take a look at the internals and see if I can find a smoking gun within it.

Only one day of testing still makes me nervous but my gut instinct always said it had to be something that changed during the pulley install. Seemed too coincidental that the TB just happened to go out. I can 100% recreate the problem using the MAF theory and since the original TB is perfectly fine during testing I want to say this is case closed.

 

That was a painful learning experience, glad you found the fix.

 

Glad to hear you hopefully found it.

Dumb question if you logged TPS both at the pedal and at the TB with HP or EFI live wouldn't it show it hitting something and one stopping or did it just force it's way past it? I guess I was wondering did it stop the blade or did it just graze it enough to cause a glitch setting off the code?

 

Thanks OP.

 

When you hear the stories of people with the same problem and it was because the plate was getting slightly caught up on a burr or buildup, I believe I had an artificial burr basically. The throttle plate would literally only touch the maf plate in the very middle. That means it wouldve had to of been at basically 70-90 degrees open. When I go back and look in this thread I even mention that when we tested...

"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."

This test was before I replaced the TB though... So the problem was found at this point and I misinterpreted this as a bad TB (which I feel most would as well)...

I could tell from looking at the MAF itself where the throttle plate had started to "cut" or chip into the plastic maf plate. I had noticed this one of the when times I took it off, but I had dropped it and assumed the chipping was from that. Hindsight is 20/20. I was staring at the problem in January and didnt realize it.

Spent so much time looking for a single failure that I didnt stop to look at the entire picture together. Every part was fine by itself. It was when they were put together that it became a problem.


p2101 = your throttle plate is not matching what your pedal input is
p1516 = The problem is your Throttle Body internals (voltage inconsistencies)(potentially can be tuned out)

Explains why once I resolved the main problem I would only get p1516

Basically the new TB I purchased made it so that every piece I replaced from that point in time (mid January) wouldn't solve the problem. Because at that point the problem WAS that throttle body along with the MAF (at times). If I could go back to December 23rd when I picked the car up after the pulley install, I would unbolt the coupler on the MAF and slide the MAF back 1/4 an inch. I would've then used all the money I ended up spending to buy a rear set of r888's and would be making a post Mar 20th about how I got my *** kicked at TX2k16 but had a great time

Such is life though. The silver lining is I most likely understand the workings of the LS2 throttle body more than 99% of the GM techs.