Went to a dyno day this weekend. My passenger LTFT's were in the single positives, so they bumped the base a click to get it negative. Did a pull with the AFR, and it was between 11.0 & 11.7 with the WOT set at 'E'. Bumped it down to 'B' (10% lean) and it raised it to 12.0 to 12.7. I believe they reset my LTFT's at least once.

Captured Autotap data today, and did a WOT pull from 1500 through 5500 in 4th gear. I received a consistent 2.5-4* of KR at all 27 samples. I could hear it as well. Now, before I went to the D-day, I did have some KR but it wasn't this bad. Looking at the previous log, it was typically 1-2* at various points, and a couple times above 5200 it would have 2-3* of KR...but not for the whole pull.

Do I richen it back up again to get rid of the KR, or is it a result of resetting the LTFT's, or...? I'd rather be making less safe power than listen to a popcorn maker.

TIA... <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

 

Jim,

I looked at the two logs I had for your first two dyno runs. You had a sigificant amount of KR in both runs. I also noticed that the commanded A/F ratio was 11.7:1. This indicates you have a stock PE table. Did Ed revert your tuning back to stock when you were there?

Tim

 

I honestly do not know. I told him that the compression on my heads was advertised as 10.8:1. He said he tried three different spark tables, ending at 11:1 and still received detonation. He said it was probably bad gas and/or low fuel pressure. His assistant, John, had the fuel gage on and they stopped monitoring around 4000RPM due to bad detonation. The fuel pressure was about 56 at that time. I e-mailed him a few months ago and he claims my PCM is locked. I really have no idea what he's done to it...that's why I want to be directly involved in further tuning.

The autotap log I have from December shows less KR up until ~5000RPM's. I can forward that to you tonight if you want.

 

I don't believe it's correct to make a change that affects the closed loop AFR, and expect to see immediate changes in the LTrims. They are, after all, "Long Term Fuel Trims".

I believe it takes some time driving around for the LTrims to settle out. Whenever I make a tuning change, it takes my car a couple days for the LTrims to read consistently in all the different fuel trim cells I hit while driving.

As for your KR problem, I can't say for sure how to fix it with just a MAFT, but with LS1 Edit, I would try richening the WOT fuel (the PE table) first, and then pull timing as necessary.

 

Hey Jim.

Are you using Edit on your car as well? I agree with Dean. You'd need some driving miles in order for the Lterms to settle down and get a consistent - value. At WOT, do you Lterms 0 out or are they showing an integer?
When you lean the car with the MAFT I think it increases timing (at least it seems plausible since it pulls timing when you richen with MAFT).

 

LTrims will adjust as soon as the STrims begin to go too far from 0. It may take some time to hit all of the trim cells but that is far different from the response time of the STrim/LTrim logic.

In Jim's case the LTrims were 0 at WOT thus have no bearing here. The problem is that there is too much timing advance for the combination. Rich or leaner it still had a lot of KR. The timing advance needs to be dropped a bit for his combination. It is not an A/F ratio issue.

Tim

 

in my experience, changes with a maft arent seen until at least the second dyno pull in a row.

what is the timing at?

 

This is the WOT run in 4th...

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">code:</font><hr /><pre style="font-size:x-small; font-family: monospace;">STerm Fuel Trim B1,LTerm Fuel Trim B1,STerm Fuel Trim B2,LTerm Fuel Trim B2,Engine Speed,Vehicle Speed,O2 Sensor - B1S1,O2 Sensor - B2S1,Fuel Trim Cell,Knock Retard,Engine Coolant Temp,Throttle Pos Ang,Ignition Timing Adv,Intake Air Temp,MAF Air Flow Rate,Current Time
0.0, 0.0, 0.0, 0.0, 1496, 32,0.925,0.945, 22,3.8,180,100.0,18.0, 61,9.74,19:30:04.55
0.0, 0.0, 0.0, 0.0, 1626, 35,0.930,0.950, 22,3.63.6,180,100.0,18.5, 61,11.29,19:30:05.54
0.0, 0.0, 0.0, 0.0, 1855, 40,0.935,0.960, 22,3.9,180,100.0,19.5, 61,12.93,19:30:06.14
0.0, 0.0, 0.0, 0.0, 2020, 43,0.935,0.955, 22,3.8,180,100.0,20.5, 59,13.52,19:30:06.75
0.0, 0.0, 0.0, 0.0, 2163, 47,0.935,0.960, 22,4.0,180,100.0,21.0, 59,15.65,19:30:07.35
0.0, 0.0, 0.0, 0.0, 2344, 51,0.945,0.965, 22 22,3.8,180,100.0,22.0, 59,15.41,19:30:08.34
0.0, 0.0, 0.0, 0.0, 2550, 55,0.935,0.955, 22,3.4,180,100.0,23.0, 59,17.30,19:30:08.95
0.0, 0.0, 0.0, 0.0, 2694, 58,0.940,0.935, 22,3.0,180,100.0,23.5, 59,19.73,19:30:09.50
0.0, 0.0, 0.0, 0.0, 2842, 62,0.940,0.955, 22,2.6,180,100.0,22.5, 59,20.52,19:30:10.10
0.0, 0.0, 0.0, 0.0, 2994, 65,0.930,0.950, 22,3.5,180,100.0,23.5, 59,22.54,19:30:10.70
0.0, 0.0, 0.0, 0.0, 3146, 68,0.930,0.955, 22,3.1,180,100.0,23.5, 59,22.57,19:30:11.31
0.0, 0.0, 0.0, 0.0, 3307, 72,0.925,0.940, 22,2.6,180,100.0,24.0, 59,22.61,19:30:11.91
0.0, 0.0, 0.0, 0.0, 3472, 75,0.910,0.935, 22,3.8,180,100.0,23.0, 59,23.45,19:30:12.52
0.0, 0.0, 0.0, 0.0, 3632, 79,0.895,0.940, 22,3.1,180,100.0,23.0, 59,25.08,19:30:13.12
0.0, 0.0, 0.0, 0.0, 3792, 82,0.905,0.935, 22,2.5,180,100.0,22.0, 59,26.68,19:30:13.67
0.0, 0.0, 0.0, 0.0, 3946, 86,0.910,0.950, 22,3.6,180,100.0,21.0, 57,27.69,19:30:14.27
0.0, 0.0, 0.0, 0.0, 4093, 89,0.905,0.945, 22,2.8,180,100.0,21.5, 57,30.52,19:30:14.88
0.0, 0.0, 0.0, 0.0, 4262, 93,0.915,0.950, 22,2.3,180,100.0,21.5, 57,29.73,19:30:15.48
0.0, 0.0, 0.0, 0.0, 4406, 96,0.905,0.940, 22,1.8,180,100.0,22.0, 57,31.73,19:30:16.09
0.0, 0.0, 0.0, 0.0, 4562, 99,0.915,0.950, 22,3.1,180,100.0,20.0, 57,33.08,19:30:16.69
0.0, 0.0, 0.0, 0.0, 4700,102,0.915,0.945, 22,2.5,180,100.0,20.5, 57,34.13,19:30:17.29
0.0, 0.0, 0.0, 0.0, 4849,105,0.915,0.950, 22,1.9,180,100.0,21.5, 57,36.34,19:30:17.84
0.0, 0.0, 0.0, 0.0, 4973,108,0.900,0.955, 22,3.8,180,100.0,20.0, 57,36.64,19:30:18.45
0.0, 0.0, 0.0, 0.0, 5105,111,0.905,0.945, 22,3.1,180,100.0,21.5, 57,37.62,19:30:19.05
0.0, 0.0, 0.0, 0.0, 5236,114,0.905,0.950, 22,3.8,180,100.0,21.5, 57,37.42,19:30:19.66
0.0, 0.0, 0.0, 0.0, 5370,116,0.915,0.950, 22,3.2,180,100.0,23.0, 57,38.70,19:30:20.26
0.0, 0.0, 0.0, 0.0, 5483,119,0.910,0.955, 22,3.7,181,100.0,22.5, 57,41.14,19:30:20.86</pre><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">

 

If I've deciphered that correctly, your timing is ~22 right?
That seems pretty low as is; especially for a pre-'01/'02 car.
Are you getting Knock in every cylinder?

 

How do I check for that?

 

Do a real-time misfire check in each cylinder. Make sure there isn't any whacky high numbers in a particular cyl . . . like #6.