Low throttle surge

[Bigred1]

Hey guys,

So I had a few issues that this forum has been able to help out and things have been great! recently though the car has developed a weird low throttle input like bucking or surge. I'll be doing 80 mph in 6th cruise control and the car feels like its almost misfiring but no cel it will buck or surge very slightly. I input more throttle and the issue goes away completely. can someone look at my tune and point me in the right direction as to why this is happen at low throttle input?? makes cruising around a chore and uncomfortable. it did not have this issue 2 days ago and nothing in the tune changed and mechanically the cars are the same.



Please see my tune
Silver 2008 C6 Z06 Updated 7-18-21 - Rev 3.hpt

[Nick912]

Your spark values are fairly high in low load regions for many larger camshafts to handle. Without a log of the event, it's hard to tell exactly where you are on your spark map. In 6th at 80mph you should have plenty enough load to avoid surging/bucking, I would expect you to have much worse surge at lower speed cruising in lower gears if excessive timing was the issue. Another common culprit is overly aggressive spark smoothing values, but you have that disabled so that's not your issue. Again, without a log of the event it's hard to tell for sure, as any number of factors could be the culprit.

Edit: Noticed your other thread, I see you found your issue.

[Bigred1]

Yeah for the time being I believe I found the issue. Does that make sense though? Can the IVT?s effect something like that?

[Bigred1]

Your spark values are fairly high in low load regions for many larger camshafts to handle. Without a log of the event, it's hard to tell exactly where you are on your spark map. In 6th at 80mph you should have plenty enough load to avoid surging/bucking, I would expect you to have much worse surge at lower speed cruising in lower gears if excessive timing was the issue. Another common culprit is overly aggressive spark smoothing values, but you have that disabled so that's not your issue. Again, without a log of the event it's hard to tell for sure, as any number of factors could be the culprit.

Edit: Noticed your other thread, I see you found your issue.

Went for a cruise and it did not fix my light throttle cruise control issue. Can anyone chime in on possibilities?

[Bigred1]

Your spark values are fairly high in low load regions for many larger camshafts to handle. Without a log of the event, it's hard to tell exactly where you are on your spark map. In 6th at 80mph you should have plenty enough load to avoid surging/bucking, I would expect you to have much worse surge at lower speed cruising in lower gears if excessive timing was the issue. Another common culprit is overly aggressive spark smoothing values, but you have that disabled so that's not your issue. Again, without a log of the event it's hard to tell for sure, as any number of factors could be the culprit.

Edit: Noticed your other thread, I see you found your issue.

Please see my current tune and a few logs I took tonight. I noticed the "surge feeling" with the cruise on again and I saw some knock in the logs just cruise control. any idea?

Silver 2008 C6 Z06 Updated 7-13-21 - test - 28.hpt
Data log 2.hpl
Data log 1.hpl