MCP TPS Limit Fail, LY6 Swap

[RADustin]

Gents,

Working on a E38 LY6. LS3 throttle body. VVT in-tact, using a 2008 burb base file. Corvette pedal, wiring appears to be ok.

As the story goes, the engine ran fine with another 5.3 based tune, but the VVT didn't work. So they changed to this burb base.

Key on engine off when TPS hits about 60%, it appears to go into reduced engine power and limits TPS to 36-37%. It does not throw a visible code, but if you clear codes the REP goes away without cycling key.

What I notice is the error between commanded and actual TPS grows to about 8%. The TB lags the commanded. Then it errors out, you can see in the log the MCP TPS Limit fails. I'm not exactly sure what this is or how to fix it.

I see in the tune file, P2101 variables are set to 8%. Although I?m not seeing any codes, I assume this is what threshold is being broke. Thoughts?

When comparing the file to an LS3 file, I see the LY6 TB area scalar is 4552.25 and the LS3 is 5636(edit or maybe its 4725?). Could this cause an issue at key on engine off? I would imagine the airflow will be off from desired, I haven't checked- but I was going to update this value. Any chance this fixes the REP issue?


Why is the TB lagging commanded TPS so much? Is this normal?? Is the correct fix to increase the P2101 positive and negative threshold? Anyway to make the TB match commanded better? Or is it an LS3 TB thing?

Tune and log attached.

Thanks!

Charlie LY6.hptThrottle Log.hpl

[blindsquirrel]

LS3 throttle body, Suburban OS, and Corvette pedal - not likely a good recipe for anything remotely functional.

[RADustin]

appreciate your thoughts.

floor is still open for anyone with helpful insight.

also curious if anyone from the HPT crew can tell me what relationship or break point the 'MCP TPS Limit' PID is checking.

thanks

[kevin87turbot]

Several of the DTC's that could potentially cause the REP mode have been changed to No Error Reported.
Change the following back to stock error reporting mode and it'll help you determine the DTC that is causing the issue.

Change P0068 to MIL on First Error
Change P0106 to MIL on Second Error
Change P0606 to MIL on First Error

Then drive it until REP occurs and scan to determine the DTC that is causing the condition.

[RADustin]

Several of the DTC's that could potentially cause the REP mode have been changed to No Error Reported.
Change the following back to stock error reporting mode and it'll help you determine the DTC that is causing the issue.

Change P0068 to MIL on First Error
Change P0106 to MIL on Second Error
Change P0606 to MIL on First Error

Then drive it until REP occurs and scan to determine the DTC that is causing the condition.

thanks.

I haven't been back to visit the car but did confirm it won't run a stock truck TB either- so I know its tune related.

The OS is shared with an 08 LS3 so I'm sure the OS will support it. Just need to get the TB to act right. I think its the way they deleted torque management and such..

[PaulF]

thanks.

I haven't been back to visit the car but did confirm it won't run a stock truck TB either- so I know its tune related.

The OS is shared with an 08 LS3 so I'm sure the OS will support it. Just need to get the TB to act right. I think its the way they deleted torque management and such..

Have you been back to visit this car? Was it resolved? I am having a similar issue.

[OmarR]

Has anyone resolved this issue? I'm having somewhat of the same issue.
It's a cammed 6.0, Flat top pistons, stock 823 heads, stock LS3 intake and throttle body, and E38 ECM. On mine when the throttle gets to 80% the MCP TPS Limit goes to YES and immediately goes into reduced engine power with P0606 till I cycle the ignition or clear the code. If I don't get on the gas hard enough to reach 80% throttle it runs just fine. I realize this thread is a year old but worth asking if I can get somewhere with this thing. Thanks!

[smokeshow]

That's a soft stop in the position controller that tells you either something is damaged or you've got the wrong stuff plugged in. The actual throttle controller is not a calibratable item in HPT, for many reasons. You need to fix the hardware issues.

[OmarR]

That's a soft stop in the position controller that tells you either something is damaged or you've got the wrong stuff plugged in. The actual throttle controller is not a calibratable item in HPT, for many reasons. You need to fix the hardware issues.

There must've been something wrong in the tune I used for a 6.0 seg swap. I seg swapped back to my original 4.8 tune and changed the engine size from 4.8 to 6.0 and new injector data and have driven it hard for about 30 minutes tuning the MAF high and low tables and still no REP or p0606 code has came up. Thanks for your response Smokeshow! Now if I can only figure out how to tune the VVE table and where to find it lol. Is it named something different on gen 4 stuff vs gen 3? There's a few VE tables named stuff like VE lo altd VE hi altd and then some with DOD and some with (CP) but they're all populated with 0's. Any suggestions?