2007 Corvette lean at partial throttle

[mikel]

Its not that it is lean, more likely due to added part throttle timing which we did to improve fuel economy....
Email me the current tune from the car and we'll see if we can correct the issue.

Thanks

[jmwigen]

Thanks for the program change. Unfortunately, it didn't do the trick. Now its pinging as you go up through the gears (from 3rd gear upwards) at a light throttle setting, as well as at cruise, (65 to 70 mph) when you add just a little throttle in 4th 5th, and 6th. I notice that my fuel air ratio is saying 14.75 while running in real time data mode. LTF is at -.78 Hope this helps a little. Pls advise. Thanks, Michael.

[sohfast94]

I can take a look at it for you...

[mikel]

Here you go, try this file...

[jmwigen]

Wow, thanks for the quick delivery of the new tune. It's better, but can still detect audible ping in 5th and 6th. Suggest more of the same and I believe we'll have it. Still seems lean to me, as going across "The Flats", a 5 mile straight, i'm seeing 34 mpg in 6th at 65 mph. Will stand by, and thank you again. Michael.

[sharkzf6]

jm - there is no way to get rid of the minor "pinging" you describe if you are lugging or short shifting the transmission. Even on my A6, since it behaves like a manual - in other words I can short shift and lug - I will notice very minor pinging in this situation. I wouldn't give it another thought. The thing runs like a raped ape when driving aggressively ...

And yes, GM detunes the LS2 engine for fuel economy and the fact that many folks put low grade, low octane fuel in their Vettes! Yikes! Say it ain't so!

[jmwigen]

To: sharkzf6- Thanks for your input.Nice to see other Vette owners chipping in---- My engine didn't ping in stock tune, only with the new tune. As for lugging, (And I'm using 94 octane fuel) I wouldn't consider feathering the throttle at 76 mph in 6th as lugging. If I need to apply any significant amount of power, I'll drop down a gear or 3. My other fun ride is a Mini Cooper S that we've taken from stock at 160 hp to the mini Madness Stage 3 kit which yields 235 hp. Madness also reprogrammed the ECU and it does not ping. My bet is that the boys at Diablo can fix my little pinging problem. And, you are right, it does go like a scalded cat. With the mods, I'm right at 9.5 seconds 0 to 100. (Bet you're going to go right out and do a timed run!!) Let me know. Tks, Michael

[jmwigen]

T0: Mike Litsch. Thanks for your time on the phone. As I said, whatever was done to modify the tune last time was working, and I believe that more of the same would be the fix. Thanks again, Michael.

[mikel]

Try this:

[jmwigen]

Hi, Mike. Thanks again for the change of tune. It's still pinging but at a slightly reduced level. Is there any way to richen it up at partial throttle? As I said, WOT is good, with an air/fuel ratio in the mid to high 12's. Cruise, as you explained, still is 14.75, and its fine until you feather the throttle. Thanks, Michael.

[concoursd]

reduce your injector slope, that will cause the pcm to increase part throttle fueling. Then re-check your WOT settings and compensate as necessary as the injector slope is a global adjustment that affects part and WOT fueling.

Are you getting any KR during your datalogs?

[jmwigen]

Getting very little KR, only every once in a while while I'm actually trying to induce pinging. None in steady state speeds from low to over 90 mph. Will try the injector slope change. Thank you, Michael.

[jmwigen]

To: Mike Litsch. Have run 400 plus miles since last program update and still no change. I now understand a little more about what you were getting at with the timing being advanced. Steady state at 70 mph in 6th I'm seeing 33 to 34 degrees of advance. Feathering the throttle produces pinging, but the timing takes a few seconds before it starts to head down to the 20's. Further advancing the throttle to about 50% takes the timing down to around 12 to 15. Can the program be made to be more responsive to slight throttle increases? Tks, Michael.

[mikel]

To: Mike Litsch. Have run 400 plus miles since last program update and still no change. I now understand a little more about what you were getting at with the timing being advanced. Steady state at 70 mph in 6th I'm seeing 33 to 34 degrees of advance. Feathering the throttle produces pinging, but the timing takes a few seconds before it starts to head down to the 20's. Further advancing the throttle to about 50% takes the timing down to around 12 to 15. Can the program be made to be more responsive to slight throttle increases? Tks, Michael.

You know, this is really an issue that could be solved with a simple downshift, no?
If you tried to go 50% throttle on an automatic, it would downshift just to avoid this very issue...

There is plenty of talk on the forums about not 'lugging' any car in high gear/low rev situations as it is not a good idea...

[jmwigen]

Sorry, Mike, but no, this is not a simple downshift issue. Obviously, if I need 50% throttle I will go down a gear or two. This is about a light throttle application to go from 70 to 75 mph, or hold 70 up a VERY slight grade. The stock program did not ping. Read back a few posts about my Mini. It doesn't ping, either. Am I holding unrealistic expectations about the intake, header, exhaust, and programming mods? Should it not be able to run as well as stock? Thanks again for your efforts. Michael.