Strange looking part throttle 02 readings...

[marc_w]

Hey guys.

I'm running a SD/MAFless tune here, tuned via the narrowbands.

I just installed some higher ratio rockers to compliment my lower lift cam. I feel as though certain parts of my power range did not benefit from the mod as well as other areas did.

An example here is this mid throttle, 2nd gear squirt.

Why do my 02's in that area look so....... decrepit? Is that normal?

The truck has 34,000 miles on it. It's had a cam in there for the last 15 or so. One bigger stick, and now this smaller one.

Older logs look similar to the above, but with the 02's more centered around 450mv. I don't like how they appear to be hanging high (rich) now, with no apparent effect to LTFT's. (LTFT's are enabled).

The 02's appear to be sweeping just fine in most other areas of the power range.

Thanks,
-marc

[marc_w]

Another example.

[MNR-0]

The O2s look fine to me.

Looks to me like you have another problem. At 3000RPM and 45% TPS and 85% TPS at 2200RPM you are still in closed loop? No wonder you are getting knock.

Whats your PE enable vs TPS table like?

[marc_w]

It's 90 across the board... I had it lowered, but I don't care for the performance, especially having my WOT fueling fully untuned.

Where would you recommend having PE come in? That's something I could never find a straight answer for.

Yeah, I've got knock in those graphs because of my own insatiable curiosity.

I have a decent HO timing table build that will only give 1* of KR every once in a while under high-load, lower throttle openening situations. (I had to lower a good amount of those cells in the stock table)

I wanted to see how 89 octane gas would effect things, seeing as I tuned using 91.

[MNR-0]

I would recommend the following PE vs TPS settings. You dont want that much closed loop with the throttle open that wide. At worst case you are setting yourself up for pre-detonation, a real engine killer.

Cold
64 64 64 64 64 64 64 64 64 55 45 36 26 26 26 26 26 26 26

Hot
47 47 47 47 40 33 26 19 19 19 19 19 19 19 19 19 19 19 19

[marc_w]

Wow, that low, huh?! I'll plug it in right now.

Thanks for the recommendation, and for looking over things. I appreciate it.

[txhorns281]

Wow, that low, huh?! I'll plug it in right now.

Thanks for the recommendation, and for looking over things. I appreciate it.

Don't forget to set the ECT to activate your HOT TPS table. Otherwise you PCM only recognizes your Cold.

[jimmyblue]

Are you guys using HOT for a protection function, or are you using
HOT = "fully warmed up"? Just curious, I looked at the stock HOT
threshold and it looked like an overtemp value to me.

I don't see anything bad about the O2s where the markers lie,
they swing fast and tight and I think this has to do with high
exhaust airflow and more RPM making more frequent cross-counts
and less excursion into "stupid places". I suspect that the closed
loop mixture "dithering" happens proportionate to RPM, maybe on
a revolution based cycle, as the switch-rate appears to me to be
RPM-following. At some point it just doesn't bottom out anymore
but I believe that's a -good- thing. A saturated O2 (ceiling or floor)
means you're spending time with a mixture that is not right. At
least here, it's bouncing more off the high end which favors power
rather than ping.