CTS-V Burst Knock?

[tlsmikey]

I'm getting some sort of hesitation on my 2010 CTS-V. It was tuned professionally, but there is a hesitation that I can't get away from in the 2k-3k range.

Mods:
2.55 Upper Pulley
Ported Snout
ported Throttle Body

I can't tell if its real knock or not. I'm of the assumption that it is NOT since i don't see the KR reading moving at all.

Any thoughts on how to solve this issue?

Log attached. The real fun begins at around 50 seconds in through 1.05. It's much easier to discern in 6th.

Thanks,
Mike

[edcmat-l1]

Look at your MAP pressure. You're in boost, but still in closed loop, NOT in PE. That's your problem, not spark. Post your tune and let's take a look at how your PE is setup.

[tlsmikey]

Thanks for the quick response. Let me know if this helps.

[edcmat-l1]

Give this a try and see if it doesn't work a little better. Run a data log and post it back up here.

Attachment 37746

[tlsmikey]

Wow! Swear i just picked up 25HP/Ft.lbs. Much better. There might be a very tiny bit of hesitation from 2800-3000RPM, but its hard to tell. I took a bit longer log file and it felt great overall.

It looks like you changed the HOT Power Enrich, PE Enable TPS. So, if I understand correctly, this is the TPS setting at which WOT fuel tables apply. Is that correct?

Thank you again for your help so far.

[edcmat-l1]

Wow! Swear i just picked up 25HP/Ft.lbs. Much better. There might be a very tiny bit of hesitation from 2800-3000RPM, but its hard to tell. I took a bit longer log file and it felt great overall.

It looks like you changed the HOT Power Enrich, PE Enable TPS. So, if I understand correctly, this is the TPS setting at which WOT fuel tables apply. Is that correct?

Thank you again for your help so far.

Yeah the E67s/LSAs can be a little tricky to setup the PE enable. That there is the quicky version. To make it much better than that would take some dialing of the VVE and the spark tables to get it best as possible.

You're welcome.

[tlsmikey]

Any downside to running this at the values that you sent?

Should i be looking for a value just below the original that eliminates the problem, or should i stick with the value you provided?

[edcmat-l1]

Any downside to running this at the values that you sent?

Should i be looking for a value just below the original that eliminates the problem, or should i stick with the value you provided?

I'd run it just like it is.

[edcmat-l1]

Any downside to running this at the values that you sent?

Should i be looking for a value just below the original that eliminates the problem, or should i stick with the value you provided?

OK, so I'll elaborate a little. The E67s and specifically the LSAs sometimes have problems entering PE, and the way I set yours up seems to work best. The way yours is setup, it doesn't look for anything other than the MAP pressure. At 85 Kpa, regardless of TPS, it will enter PE. You won't be running around town in PE. You won't see any significant reduction in mileage. All that will happen is when you tip in the throttle, and the MAP Kpa gets close to atmosphere, when you're on the verge of entering boost, your PE will enable.

The key here is to NOT use the TPS enable. If you look at your previous log you posted, you were in the TPS enable range (47%), along with the MAP enable (well over enable at 141 Kpa), and you still were not in PE. I've seen this in several of these and the ZL1s too.

[ZO6_Bryan]

OK, so I'll elaborate a little. The E67s and specifically the LSAs sometimes have problems entering PE, and the way I set yours up seems to work best. The way yours is setup, it doesn't look for anything other than the MAP pressure. At 85 Kpa, regardless of TPS, it will enter PE. You won't be running around town in PE. You won't see any significant reduction in mileage. All that will happen is when you tip in the throttle, and the MAP Kpa gets close to atmosphere, when you're on the verge of entering boost, your PE will enable.

The key here is to NOT use the TPS enable. If you look at your previous log you posted, you were in the TPS enable range (47%), along with the MAP enable (well over enable at 141 Kpa), and you still were not in PE. I've seen this in several of these and the ZL1s too.

I have a ZL1 with a 9.55 pulley so I am interested in this also. Mine seems to hit PE at about 47-48% throttle. I see and understand what you are trying to do. But the PE Throttle Hot table is set to enable PE at only 19%(stock tune). So are we missing a PE Throttle Cold table that is set at 47%? If so, then the PE Throttle Hot settings won't change anything.

[10_SS]

I have a ZL1 with a 9.55 pulley so I am interested in this also. Mine seems to hit PE at about 47-48% throttle. I see and understand what you are trying to do. But the PE Throttle Hot table is set to enable PE at only 19%(stock tune). So are we missing a PE Throttle Cold table that is set at 47%? If so, then the PE Throttle Hot settings won't change anything.

It was explained to me that the PE enable value that you see as 19% is not linked to TPS, there is a seperate PID you have to log... and that's "PE TPS". ETC pedal or any of the others wont show the correct value.

[ZO6_Bryan]

It was explained to me that the PE enable value that you see as 19% is not linked to TPS, there is a seperate PID you have to log... and that's "PE TPS". ETC pedal or any of the others wont show the correct value.

Not talking about log value. 19% PE enable is the value in the VCM Editor file.
47% is the value in the log that it goes into PE.

[DSteck]

The PE enable TPS is actually open throttle area minus the idle portion. That's why 40-something percent throttle is what it takes to trip into PE.

[edcmat-l1]

Regardless, it was at almost 50% TPS, and 140 Kpa. Should have been in PE. The way I set it up for him, as soon as it passes 85 Kpa it's in PE.

[DSteck]

Just saying... I use the MAP enable anyway most of the time. I was explaining why people are seeing the throttle "discrepancy".

[Dzz88]

I would really like to know this secret.. as this stumble, lean, whatever is driving me nuts... HEEEELLP! LOL