OK, Oxidizr and BigTex Here is a synopsis of the KNOCK problem.

INPUT PLEASE

Back to back runs (big difference)

Run 1:
Timing - 23.02 avg
02a - .88 avg
02b - .93 avg
Knock retard - .486 avg

Between 3582 and 4249
Timing - 26.5
02's - .9 or better
knock avg - .6

Run 2:
Timing - 21.09 avg
02a - .86 avg
02b - .89 avg
Knock retard - 1.91 avg <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />

Between 3302 and 4112
Timing - 21.09
02's - .89 or better
knock avg - 2.3 <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />

 

Those numbers look pretty close to what I've seen with my atap numbers.

Here is a nice long pull. Atap didn't record KR on this run but, you can see where it sneeks in there around 4000rpm.

It never gets over 1.5 and slowly drops to nothing by the shift.

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">code:</font><hr /><pre style="font-size:x-small; font-family: monospace;">RPM MAF Rate O2 B1S1 O2 B2S1 ITA TPA LTermB1 LTermB2

2412 12.65 0.695 0.730 21.0 100.0 1.6 1.6
2784 15.63 0.880 0.900 26.5 100.0 1.6 1.6
3555 20.47 0.900 0.905 26.5 100.0 1.6 1.6
3566 20.30 0.900 0.905 26.5 100.0 1.6 1.6
3591 20.25 0.905 0.905 26.5 100.0 1.6 1.6
3641 21.50 0.895 0.905 26.0 100.0 1.6 1.6
3660 20.98 0.905 0.900 23.0 100.0 1.6 1.6
3704 22.18 0.905 0.905 25.5 100.0 1.6 1.6
3728 20.18 0.900 0.905 26.0 100.0 1.6 1.6
3766 21.69 0.905 0.905 26.0 100.0 1.6 1.6
3800 23.64 0.895 0.905 26.0 100.0 1.6 1.6
3828 23.09 0.905 0.905 26.0 100.0 1.6 1.6
3877 23.36 0.895 0.905 26.0 100.0 1.6 1.6
3892 21.64 0.900 0.905 25.5 100.0 1.6 1.6
3928 23.92 0.895 0.905 25.5 100.0 1.6 1.6
3965 22.69 0.890 0.905 25.5 100.0 1.6 1.6
3992 24.21 0.890 0.905 25.0 100.0 1.6 1.6
4020 22.83 0.900 0.905 23.0 100.0 1.6 1.6
4057 23.64 0.890 0.915 23.0 100.0 1.6 1.6
4075 22.83 0.895 0.900 23.0 100.0 1.6 1.6
4126 24.11 0.895 0.905 23.5 100.0 1.6 1.6
4158 24.11 0.900 0.905 24.0 100.0 1.6 1.6
4175 25.27 0.885 0.905 24.0 100.0 1.6 1.6
4192 26.30 0.890 0.905 24.0 100.0 1.6 1.6
4275 25.20 0.895 0.905 24.5 100.0 1.6 1.6
4242 26.30 0.885 0.905 24.5 100.0 1.6 1.6
4297 25.27 0.890 0.910 25.0 100.0 1.6 1.6
4326 25.55 0.895 0.905 25.0 100.0 1.6 1.6
4332 27.75 0.890 0.905 25.0 100.0 1.6 1.6</pre><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I think it could be load induced since it only seems to happen when the trans. doesn't downshift and get the rpms up high.

Have you tried some high octane gas mixed in with your regular gas to make sure its not real?

John

 

hey do you have this on an excell spreadsheet? i just made a log on mine yesterday. my average knock retard for when i was at wot (2 - 3 different occasions on the log) was 2.95 <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />

i just cant figure the **** out, probably be better once i get back up to dallas and can make changes if i need to with ls1 edit.

everything seemed really good tuning wise too, im guessing its false knock.

through the entire log...

average ltrims at part throttle: -3.77

average o2s at WOT: .906

average knock retard at WOT: 2.95

greg, when you are getting your knock retard. are either of your ltrims in the positive area? if so this could be one of the reasons. when your ltrims are in the positive before you go WOT they will stay in the positives. On the other hand, if they are in the negatives they will zero out at whatever is considered WOT. May not sound like that big of a deal but when it doesnt zero out its running your Power Enrichment table for fuel with the ltrim still being used as a multiplier.

i noticed the main time i was at WOT and one of my ltrims wasnt zero'd out so that screwed it up. i think i am going to richen it up a little bit more so that it will surely zero out.

then again, you could also be getting a simple case of false knock <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

bryan

<small>[ July 29, 2002, 10:31 PM: Message edited by: really slow truck ]</small>

 

Did MTI give use a wideband when you made your dyno pulls? Most people shoot for .90 O2s during WOT, so I did the same. Then on the dyno, with the wideband, my O2 were high 80s, but the wideband showed me below 12:1 which is pretty fat.

Most of the small KR (1* or less) is pretty random from what I've seen, it may or may not show up in there every time. Now the stuff that comes in over 2* is probably caused by something. False knock? - maybe. If you have the HPP3 tuning going, it adds timing to both your high and low octane tables, but it also reduces fuel at WOT. The theory behind that is that these truck run rich from the factory. The higher timing is good, but if you were already leaned out (by adding exhaust and intake, etc..) the HPP may have removed too much fuel from that RPM range. Also when you se knock, look at the RPM that the initial KR showed up ( and any values where it grew). After KR shows up, it will slowly deteriorate back to 0. So if you see 3* @ 3000, at 3300 you may have 2.3, and 3600 may show 1.8. That is from the slow process of KR being removed. Funny thing is - I have knock down low and up high, but that range 3-4000 I have the least amount of knock.

Like Bryan said - do you have an excel spreadsheet of this?

 

2-3*... I wish! I have a few logs where my KR was up close to 7* in that same RPM range in second gear. I will have to get the log off the laptop and post it up here for comparison.

 

Damn you guys get a lot of knock retard. NA at WOT I don't see any knock retard. On the bottle (100 hp dry shot) I saw 6.7 degrees KR around 4400 rpm's and wet shot 125hp saw 5.2 degrees around 4200 rpm's. All I can figure is that running more fuel helped with KR problems. I have no computer tuning mods done to the engine either. I think what BigTew said is probably the most accurate assumption for KR. If tuning was used it is advancing too much while being too lean.

 

Here is my crude way of posting a spread sheet.
<img src="http://home.swbell.net/greghud/autotap.jpg" alt=" - " />

 

Greg - Here are a few quick observations and suggestions:

On WOT runs, dont log Ltrims, enginge temp, or throttle pos. The fewer the items logged, the quicker the data is collected. Ltrims have nothing to do w/ WOT, temp is nice, but wont change much, and you will know when you hit WOT because your O2s will jump to the 90s (or 80s) and stop fluctuating. You might also add MAF to your logging. I could tell you what you timing should be if I saw that figure.

- I don't like the way your O2s are so different. (ex. .90 on bank one, and .95 on two) Swap your front O2s to opposite sides and see if the readings change any. Do you have any misfires logged in your autotap? That could acount for unburned fuel causing a higher than notmal O2 reading.

- In the middle of run 1 - a little of knowck occurs. That could be caused by how rich you are running. .965 on your O2s is pretty high. At the bottom where you see 4* of knock, that occurs during a shift. And your lower O2 reads 83, which is lean. That vould be the cause there.

- Run 2 - same thing as run 1, where it looks like you are rich one second, then lean the next. BUT - notice this: You KR occurs mostly during the shift. Then it is slowly deteriorating its way back to 0. This is by design in the PCM.

Do you have hypertech tuning on? If so, it will lean out the upper RPMs. PLay with the other octane settings and log them. See how your O2s look then.

Richard