need HELP - WOT LS3 in speed density

[cdoggy81]

Hi guys,
I am in need of any tips or ideas as to how & proceed with this one as it has a lot of people stumped....

Everything started off as the following:
LS3 swap out of a 2008 Corvette into an old Trans Am.
Stand alone wiring harness from Current Performance, E38 computer & TCM to control the 4l80e tranny
2008 Corvette Operating System was loaded - OS & base files, Vats removed, no MAF, will be run in Speed Density (SD).
87mm CTS-V / Truck throttle body on top of a Holley Single Plane intake (this is to keep the look & functional shaker for the Trans Am as seen below).
Engine mods are: BTR cam 225/238 .612"/.585" 113+3, Ported WCC heads, 1 7/8" headers, 2.5" exhaust, no cats.

Car started up pretty easy at the builders for the first time with no major issues, just pig rich so all we did was drive it around the complex a bit to make sure everything was working properly & mechanically safe to take it to get tuned. Got the car in to the tuner finally & was able to to start the process. We get all the basic parameters adjusted, set it to fail the MAF on startup & started working the SD tables. Started right up after the re-flash & even idled better so we took it for a run to start filling in the tables. Got back to the shop to load some more info & she would not start again after turning it off. After a lot of back & forth (thinking it was a fuel pump, maybe wiring or a bad ground, bad computer, etc.) we determined that the corvette OS did not like the fact that we had an 87mm truck TB on there vs the stock 90mm corvette one. When I got her back home on the trailer & the next day put the stock corvette TB back on the problem was solved. Started up every time, idled good, drove around good (nothing fast or hard).

Brought the car back to the tuner & he loaded a truck OS overtop of the corvette so it would now work with that TB but as my luck goes it bricked the computer.... :l So now I have to buy a new e38 computer from the dealer & have it all setup from the start for a 2012 Silverado. At least we now have a clean slate & correct base OS to work from.

Back at the tuner everything is working good with the new e38 & base OS, it is taking all the changes & file adjustments he is throwing at it in HP Tuners. All is looking good until we start doing wide open pulls. When we go WOT the car goes into protect mode every time. We reset everything & try it again but this time by rolling into the throttle & it seems like once you hit a certain RPM (say 4500+) or throttle position (like 2/3 open +) it goes into protect mode. Tuner asks out of the blue if the TB has been modified bc sometimes over ported ones cause problems. Sure enough I said yes this is a ported TB out of a CTS-V. He said that maybe causing the problem so we decide to buy a brand new 87mm truck TB for the 2012 Silverado just to be safe as it should fix the issue... :l

TB comes in & a few days later I am back at the tuners. We put the new TB on., she starts right up, we take it out to start tuning again & same issue, limp mode at WOT!!! It didn't fix anything.

Does anyone have any ideas as to what could be causing it to go into protect mode? What are we missing as I am at the end of my my rope here... Thank you all very much for any help or direction!

This is a professional build & not a back yard conversion as you can see:

IMG_4811.JPG

IMG_4814.JPG

IMG_4812.JPG

[blindsquirrel]

Post the tune file currently in use.

Is this a tune file that was originally an auto trans, and there's now no TCM present?

Are you and/or the tuner aware there are two ETC-related segments in the ECM that HPT cannot access, and changes between operating systems leave the previous ETC programming unaltered?

[cdoggy81]

Thanks for the info.
I?ll try to tune file from the tuner but I suspect he may not share that information :-(
I have a TCM to control the 4L80e.
I?ll ask him about the unaccessable ETC file but I would have thought after bricking the first e38 & getting a new one we are starting from scratch. Not the car thinks it is a 2012 Silverado, with a new Computer, a clean OS & correct matching TB. Clearly that didn?t fix it though :l

[blindsquirrel]

Well I'm sure any tuner good enough to have proprietary anything will be able to figure this out any time now. Good luck.

[kevin87turbot]

It's hard to say what is causing the issue without looking at the calibration or knowing which codes are present during limp mode.

I've tuned a few that had very similar combinations to yours, so it can certainly be made to work.

Here are a couple things that you can look at.
Max out the default transmission TM table that is located in the Engine TM tab. If you are running an aftermarket TCM, or a manual transmission, it will shut your throttle at 4k rpm.
It's also best to use a 2wd cal file. On the 2012 model E38 applications, the ECM will be very unhappy if it expects to see a t-case and there isn't one there.

If that doesn't fix the issue, give us a list of the codes that are present when it goes into Reduced Engine Power mode.

[cdoggy81]

I will reach out & see what information he can provide me, files I don't know but codes I can't see being a problem.
I did get a message to look for a p2135 (maybe another code?) as one of his wires in the throttle body grounded out & causing problems. Another tip was the table in the diagnostics that sets max delta maf vs SD and puts you in limp mode if you fall outside that error. There is another that sets error on commanded vs actual tps & it is likely we may need to increase both tables to avoid setting the error.
In addition I will mention the TM table as well as the 2wd file.
Thank you very much for any & all suggestions. This is costing a ton & causing me a huge headache for something that was to be such an enjoyment after so many years of building ;(

[cdoggy81]

I did just hear back from the tuner & another reason this is so frustrating is bc it is not throwing any DTC's!
Also airflow limits are maxed as airflow diagnostics are disabled when he does a new camshaft tune.
We are going to go back through & verify the entire OS did in fact make it onto the PCM. Fingers crossed.