KR at WOT with low/moderate Timing (logs attached)

[LastCall]

Ran the car (01 trans am, SLP airbox only) stock tune on the dyno this morning. Was getting 1-2 degrees of KR from 4000 rpm and up. I'm thinking it may be burst KR since it the timing was relatively low. Car has 91 in it, and I did not hear any audible knock.

Any ideas?

[joecar]

Was the knock audible...?

Try zeroing BKR and see if it goes away.

MAF seems a little low at 250 g/s @ 5200+ rpm (actually it seems to drop off)... I would expect 280-300 g/s... investigate this.

[joecar]

KR in log files does not look like real knock, but it is hard to tell unless it is real knock.

[LastCall]

Thanks Joecar.

Okay I will zero out BKR and go from there. I didn't hear any audible knock.

Weird that you say that about MAF because power fell off around 5000 rpm too. What things should I look into?

[joecar]

Is MAF dirty (clean it with CRC MAF cleaner)...?

Do you have a spare MAF to try...?

This is a 2001 TA, 346 ci engine, with SLP lid...?

[odd boy]

what is the AFR? does it have headers installed? what octane are you using? a lot of factors have to be studied....

[LastCall]

Is MAF dirty (clean it with CRC MAF cleaner)...?

Do you have a spare MAF to try...?

This is a 2001 TA, 346 ci engine, with SLP lid...?

I just pulled the MAF and cleaned it. Someone de-screened it, not sure if that would affect the reading. I have an extra one, I'll install that.

Yes, 01 TA, 346, with an SLP LID.


what is the AFR? does it have headers installed? what octane are you using? a lot of factors have to be studied....

No headers, 91 octane, AFR was in the mid 12's from 3k to 6k.

I did not log all the dyno runs, but the first 3-4 were all about 320-325 rwhp. The last two that I logged were 312 and 314. Not a huge fluctuation, but thought the KR and generally low timing was a factor in it.

[joecar]

De-screening may or may not effect the MAF reading... (on some F-cars it does, on others it does not).

The screen straightens the airflow leading to the MAF sensor element.

Take a look at this (86mm F-body, 5:1 ratio): http://www.saxonpc.com/100mm-cells-for-100.html

those are cheap enough to try and see if there is any difference (they have large/coarse sized holes so they are not an airflow restriction).

[LastCall]

De-screening may or may not effect the MAF reading... (on some F-cars it does, on others it does not).

The screen straightens the airflow leading to the MAF sensor element.

Take a look at this (86mm F-body, 5:1 ratio): http://www.saxonpc.com/100mm-cells-for-100.html

those are cheap enough to try and see if there is any difference (they have large/coarse sized holes so they are not an airflow restriction).

I have a stock MAF, so I'll try that first. In addition, I'm going to zero out BKR tables.

I'll report back what I find.