Is this Knock...?

[CajunKenny]

Below are four logs and here's a brief overview...

Log #1 is at 12psi.
Log #2 is at 16psi
Log #3 is at 16psi
Log #4 is Logs 2&3 overlayed

What I'm concerned about is what happens at rpm ~4800. At 16 psi there is a dip in AFR's and timing. This doesn't happen at 12 psi so is the ECU pulling timing at higher boost due to knock?

I have no codes.

12 PSI

16 PSI (back to back logs)

Two 16 PSI logs Overlaid

 

[CajunKenny]

I am running the MaftPro by the way...

 

[CajunKenny]

Anyone...?

 

[CajunKenny]

Bueller........Bueller.......Anyone......?

 

[SupraRon]

With all the expertise on this forum, I can't believe hasn't already answered you Kenny. Unfortunately, I am not one of those experts. Free bump for ya!

 

[CajunKenny]

Well, this section is less visited than the 'Technical' area. I probably should've posted there...

Thanks for the bump brutha!

 

[JimR]

It's hard to tell from the logs... is your 'airflow frequency out' approaching 1500hz? The ecu may be pulling a little more timing than you expect at the top end of its load table.

Something you can try is filling up with the highest octane gas you can find, putting in some octane booster too (or go straight race gas if you can get it), and try the 16psi test again.

 

[CajunKenny]

1417.75 hz on the Freq. Out Signal. Fuel cut is 1.7 khz so I wouldn't think it was that. Good thinking though...

Yeah, race gas has been a common suggestion. I'll see about doing that.

Thanks for the reply Jim!

 

[JimR]

I would treat 1.5 to 1.7 khz as the ballpark... fuel cut is determined using a variety of factors including rpm, coolant temp, etc. Airflow plays the biggest role, but AFAIK there is no hard and fast airflow fuel cut number.

 

[CajunKenny]

Agreed.

Well, it sounds like Race Gas is the next thing to do. I want to make sure everything is 100% before installing my Water/Meth Kit.