cruzc5frc

'13 ZR1 w/ LPE710 package, headers, dyno tune using HPTuners at known decent Chicagoland speed shop..

Anyone know if my changing between the different track modes should alter the engine tune?

I generally leave the full computer on but last year I changed into the different track modes and only during WOT I would get a popping sound, not sure if it was cutting fuel or something else. Only happens if I go into a track mode, not touching the computer car drives fine at WOT.

I have HPT installed with a copy of my file if anyone can point me, or maybe logging is required.

Dan_the_C5_Man

Are you familiar with PTM? Do you understand what that is and what it does?

If not, Google is your freind, watch a few GM Youtube videos on it. My guess is you will find your answer.

cruzc5frc

ahh PTM? agreed, I'll verify if its that obvious, it only happened during one of the long straights and at pretty high speed so I assumed no wheel slip.

Dan_the_C5_Man

Yeah, if that was the scenario... But if it only happend once, maybe something on the track surface? Was it a one-time deal or every time in the same place each lap?

But to answer your question, there wouldn't be seperate maps in the ECM for the different track modes (BCM).

cruzc5frc

happened multiple times but seemingly at the same part of the track around 90-110 mph and WOT (not many other sections of track to meet those same conditions)

I now have a set of dedicated wheels w/ Sport Cup 2's so this should get ruled out quick on the next track run or possibly in Mehico.

Dan_the_C5_Man

Now you have my curiosity piqued - was the popping on the throttle or off the throttle? Single pop or rap-rap-rap? Never happened on the street? Is it related to temp (in another words maybe not on the warm-up lap but five laps into the session it starts)?

I would definitely be concerned about any unusual noises while on the gas, in a straight line, at high speeds. Hopefully it is PTM kicking in for some odd reason and nothing more serious.

cruzc5frc

Yep it was easily tested both ways and zero sound when traction control and nothing is turned off. I played around more with PTM yesterday (back on my 4 year old original pilot sports for street).

My instinct tells me it was PTM but just like you said, it did NOT make sense that track day. When it happened I basically got off track pretty worried, then did one more session back to not touching a thing traction/stability related, and it didn't do it (and hasn't since in many track days while not going into PTM).

I think my question is more about when you get a dyno/street tune, is there anything in HPT that might not be adjusted properly to cause such a thing like PTM to kick in (when it shouldn't in theory being upper speeds and straight line).

Dan_the_C5_Man

What about your tire and wheel sizes? Are they stock sizes, or closer front to rear than stock? You might also have a flaky wheel speed sensor, but if it fails, it will set a code.

The only settings remotely related is under Engine > Torque Management > General > TCS, and all you can do there is mess with the type (spark, fuel cut, etc.), and some enable / disable trigger parameters - you should compare the values to a stock tune, see if anything was changed, and if so, why (or change them back).

cruzc5frc

Stock wheels and original pilot sport tires at the time (just finally got a dedicated matching OEM set of wheels and new Sport Cup2s).

The car is lowered all the way on stock bolts w/ the rear grommet cut in half. Not only speed sensors but there is also suspension sensors? I'm becoming very familiar with all the active handling components related to swapping my balancer earlier this summer.

Going to check that section in my tune now but I feel like I need to be back at the track to try and recreate. Easily having TPM kick on the street but it all comes down to why it only did that on a straight at speed. I am leaving every option open including not mashing the throttle right out of the apex which could suppress it in other sections of the track.

cruzc5frc

you have a sec to look at that section in my stock tune vs current? I could PM/email you the two files. Here is the comparison view and I'm in 4th gear on that straight.

differences in trans input/output max




clicking on 4th gear torque comparison

cruzc5frc

on that straight I should be in 4th and above 3000 rpm

Rev limiter doesn't come into play as I barely get near red line by the time i need to brake.

Dan_the_C5_Man

That's typical for tooners (MD's, and now one of my fav labels) to essentially disable TM (tourqe management), which can pull timing when "shocking" the drivetrain. Like all safegaurds, you do that at your own risk (folks will chime in and say "yeah, always disable TM", but obviously GM developed that for a good reason, and it doesn't have anything to do with gas mileage or noise pollution).

cruzc5frc

I don't understand if your saying you see something in my tune about TM disabled?

Dan_the_C5_Man

I am saying from your screen shots, TM appears to be disabled. That isn't the root cause of what you experienced, it just means if you jump on the gas / dump the clutch the engine won't pull timing during the throttle transition.

cruzc5frc

I was able to recreate it tonight. Put myself in mode 3 (sport) and WOT around 4200 rpm in both 3rd and 4th (different pulls) it will make or mimic TPM and somewhat spudder on a straight but not until then while WOT. (should be earlier if wheel slip). Previous pulls with no changes to traction/AH I do not have any issues around that RPM.

For some reason my HPT logging wasn't recognizing my IDC so even with these somewhat minimal mods I'm wondering if I'm maxing out the stock injectors...

cruzc5frc

My conservative tune was around 635whp on the Dyno. Mixed results on whether I could be maxing out the injectors in this thread but I'll work on getting the PID right and logging soon.

https://www.corvetteforum.com/forums...-good-for.html

Dan_the_C5_Man

Yeah - tuning a modified FI car is beyond my personal experience, but the basics remain; most certainly log and watch IDC like a hawk. I personally think anything above 85% needs to be looked at carefully, past 90% and you need to think about new injectors.

cruzc5frc

Ya I suppose wideband AF and IDC are what I would want to keep an eye on after recreating it. Just surprised that leaving T/C on and not entering PTM modes it doesn't do it at all and is fine throughout those bands.

cruzc5frc

Pretty sure I'm not out of injector. PTM kicking in on straight line 4200 rpm has to be the system itself and default behavior in mode 3 with sensor inputs thinking things are getting sketchy at WOT. Could be my yaw sensor slightly out of calibration/tolerance. Either way if I stick to mode 4 or 5 I don't expect it to happen but just gaining more drive time in each of the modes will allow me to learn the expected behavior.

The whole point of this thread was to make sure nothing in the tune causing or suppressing issues with the tune/motor, or something like being out of injector and causing a lean condition so I think I am safe to continue giving her hell.