Jeff's winter Corvette thread.

[aaronatstate]

What’s crazy is how something like that can improve cooling significantly

[mjannusch]

Yeah, I’d remove the rings.

Have you had a chance to do some spirited driving with it yet?

[Jeff V.]

It hit 68 here today, so we took it out to a park. We took the roof out. That was nice. I've gotten on it some. Dunno if I'd really say 'spirited' but I'm starting to feel more comfortable in it. I've got zero experience with powerful RWD cars, so I'm really paranoid. I need to find some place where I can slide it around a little and see where it breaks traction. I've already felt the rear end kick out a few times.

I'm definitely signing up for a performance driving school when I get the chance.

[Chris GTO TT]

I've done track days and Auto-X with the Miata and I'm still skittish... It has no power too.

[tabasco122]

i would do a little skrrt daily in the bmw and miata lol. maybe every other day in the brz

[Jeff V.]

As I said a few posts, back, one of the things I wanted to confirm ASAP is that the ECM is stock.

Tonight I did that Torque Pro for Android sort of does this, but there's no way to log it to a file. You'll go cross eyed entering everything manually from screen shots. So I was forced to do it the hard way. It took some fighting to get my POS eBay bluetooth scan tool to sync up with my laptop in serial mode, but once I did, I was able to pull the raw data I needed. It was all spit out as raw hexadecimal data, but at least I could copy and paste it.

I've read a few threads on the Corvette forums where everyone says this is some super secret forensic data that only GM Engineering can obtain. It's pretty funny.

GM and every other manufacturer are required to post calibration IDs and verification numbers for OBD compliance purposes. GM actually goes a little further than this and publishes calibration history for the entire car, but the engine is all I care about for now.

I'll get into the exact details of how I did this if anyone cares, but the short version is I asked the ECM for it's calibration IDs and the associated checksums (CVN, calibration verification number).

Then I went to GMs TIS2Web site, dropped in my VIN, and got the full calibration history for my car, along with all the expected CVNs. I had a lot of experience with this page back when I worked at GM Techline, so it was kind of fun to see it again.

https://tis2web.service.gm.com/tis2web/

Go grab any old GM VIN from AutoTrader or CarMax if you want to play along.
Enter the VIN, click next.
Select "K20 Engine Control Module", click next.
Select "programming" under function, click next.
Select "normal" for programming type, click next.
Then click the "complete history" button on the bottom left to show every calibration ever issued for the ECM for the VIN you selected.

Look up each part number you got from your diagnostic output, and then make sure the CVNs match the ones you got from the car.

All 8 of mine did. So I'm confident my car has a stock tune in it.

There was one other amusing thing. Whenever I'd ask for data, two modules would answer back. Fortunately there's an OBD request to ask for module names. Turns out the 2nd one was the 'CHCM-Chassis control module'. As far as I can tell, this is really just the active exhaust controller I have no idea why it's communicating during an emissions diagnostic session.

[alienviking]

My head hurts just thinking about that stuff. An you claim you're not smart?

[mjannusch]

[quote=""Jeff V.""]It hit 68 here today, so we took it out to a park. We took the roof out. That was nice. I've gotten on it some. Dunno if I'd really say 'spirited' but I'm starting to feel more comfortable in it. I've got zero experience with powerful RWD cars, so I'm really paranoid. I need to find some place where I can slide it around a little and see where it breaks traction. I've already felt the rear end kick out a few times.

I'm definitely signing up for a performance driving school when I get the chance.[/quote]

If you leave the driving mode in Tour, the car will catch almost any mistake as long as your corner entry speed is somewhat sane. Even in Track mode, it’ll only let you slide the back end a certain amount before it catches it. Unless you turn off StabiliTrack, the car tries really hard to maintain control.

It still obeys the laws of physics, but it can do an amazing job of keeping it headed where you want it to go.

[DCIV]

[quote=""alienviking""]My head hurts just thinking about that stuff. An you claim you're not smart?[/quote]

He knows what he doesn't know....he has no clue that we all don't know even a bit of what he knows.


Coop

[Jeff V.]

My head hurts just thinking about that stuff. An you claim you're not smart?

I was about to type up a post about how the hardest thing was dealing with the dodgey Chinese bluetooth adapter, when I went and looked at my log file and thought about what I actually DID.

Yeah....that shit wasn't easy

The adapter (ELM327 clone) gives you a sort of menu driven interface, so you can give it raw OBD2 commands and it handles the heavy lifting for formatting the CAN messages. But you still need to know what the output means, how the information is broken up across multiple messages, and then how to interpret that into something meaningful to reference back to the GM calibration data.

I wish I was good enough to find a job that'd pay me to do this.

[aaronatstate]

[quote=""Jeff V.""]As I said a few posts, back, one of the things I wanted to confirm ASAP is that the ECM is stock.

Tonight I did that Torque Pro for Android sort of does this, but there's no way to log it to a file. You'll go cross eyed entering everything manually from screen shots. So I was forced to do it the hard way. It took some fighting to get my POS eBay bluetooth scan tool to sync up with my laptop in serial mode, but once I did, I was able to pull the raw data I needed. It was all spit out as raw hexadecimal data, but at least I could copy and paste it.

I've read a few threads on the Corvette forums where everyone says this is some super secret forensic data that only GM Engineering can obtain. It's pretty funny.

GM and every other manufacturer are required to post calibration IDs and verification numbers for OBD compliance purposes. GM actually goes a little further than this and publishes calibration history for the entire car, but the engine is all I care about for now.

I'll get into the exact details of how I did this if anyone cares, but the short version is I asked the ECM for it's calibration IDs and the associated checksums (CVN, calibration verification number).

Then I went to GMs TIS2Web site, dropped in my VIN, and got the full calibration history for my car, along with all the expected CVNs. I had a lot of experience with this page back when I worked at GM Techline, so it was kind of fun to see it again.

https://tis2web.service.gm.com/tis2web/

Go grab any old GM VIN from AutoTrader or CarMax if you want to play along.
Enter the VIN, click next.
Select "K20 Engine Control Module", click next.
Select "programming" under function, click next.
Select "normal" for programming type, click next.
Then click the "complete history" button on the bottom left to show every calibration ever issued for the ECM for the VIN you selected.

Look up each part number you got from your diagnostic output, and then make sure the CVNs match the ones you got from the car.

All 8 of mine did. So I'm confident my car has a stock tune in it.

There was one other amusing thing. Whenever I'd ask for data, two modules would answer back. Fortunately there's an OBD request to ask for module names. Turns out the 2nd one was the 'CHCM-Chassis control module'. As far as I can tell, this is really just the active exhaust controller I have no idea why it's communicating during an emissions diagnostic session.[/quote]

Wonder if the exhaust has to be in a certain position to pass emissions, and you've stumbled onto a GM scandal

[vegasidol]

[quote=""aaronatstate""]Wonder if the exhaust has to be in a certain position to pass emissions, and you've stumbled onto a GM scandal [/quote]

I read that and it crossed my mind as well...

[Jeff V.]

Hell if I know. I did look up the calibrations for the CHCM and one of them had a note about OBD readiness flags. I may dig into it more later.

I don't see how the exhaust flaps could have anything to do with emissions. Once the exhaust has passed through the cats, the only thing that should matter is noise level.

[aaronatstate]

[quote=""Jeff V.""]Hell if I know. I did look up the calibrations for the CHCM and one of them had a note about OBD readiness flags. I may dig into it more later.

I don't see how the exhaust flaps could have anything to do with emissions. Once the exhaust has passed through the cats, the only thing that should matter is noise level.[/quote]

Are noise levels part of the restrictions out there? Or has it not gotten that far yet?

[Jeff V.]

I think there is an NHTSA rule for it. I just don't know why the module would present itself during an OBD session. OBD is strictly for emissions. Maybe there's some command to tell the system to stay closed so you don't need 4 tailpipe sniffers?

[Jeff V.]

Here's the pictures we got on Sunday.

[Chris GTO TT]

Looks great!

I notice it has a lap timer how does it work? Is it GPS based or do you have to trigger it when you complete a lap?

[Jeff V.]

I haven't played with it, but here's how I understand it.

You pull up to the start/finish line of your track. Then press a button to mark it. After that, any time you cross that point, it triggers a new lap. So it is based on GPS.

I don't know how accurate it is though. One of the selling points of the Performance Data Recorder (which I don't have, as it was only on 2015+ cars with nav) is that the GPS receiver is separate from the nav system, and it responds five times faster. So it's a lot more accurate.

[Chris GTO TT]

Okay that makes sense!

[DCIV]

Already being a vette owner and taking up two parking spots. How quickly they change.


Coop