Trim and table questions
Thread Starter
Teching In
Joined: Mar 2016
Posts: 21
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Trim and table questions Hey guys just a few things Im trying to work out and am having troubles.
1- After dialing in my lt and st trims ( all within 1 +/- ) when I reinstate maf and pe my trims are in the 2 to 3 range. Possible reasons?
2- while using 87 octaine fuel I am getting a couple of degrees of kr in spots. By default does the pcm run on high octaine table and then retard just when it detects knock or is the low octaine table being retarded further? I tuned my high table with 93. Once satisfied I saved then saved as and copied and pasted stock low octaine table to both high and low and tuned till satisfied. After that I copied low table and imported it to previous tune that had high table optimized. At that point I jad both a high and low O table that wasnt reciebing kr. Now I see that when using 87 o gas Im getting kr randomly.
Any input would definetly be appreciated.
1- After dialing in my lt and st trims ( all within 1 +/- ) when I reinstate maf and pe my trims are in the 2 to 3 range. Possible reasons?
2- while using 87 octaine fuel I am getting a couple of degrees of kr in spots. By default does the pcm run on high octaine table and then retard just when it detects knock or is the low octaine table being retarded further? I tuned my high table with 93. Once satisfied I saved then saved as and copied and pasted stock low octaine table to both high and low and tuned till satisfied. After that I copied low table and imported it to previous tune that had high table optimized. At that point I jad both a high and low O table that wasnt reciebing kr. Now I see that when using 87 o gas Im getting kr randomly.
Any input would definetly be appreciated.
TECH Senior Member
Joined: Apr 2002
Posts: 6,080
Likes: 17
From: So.Cal.
1. you also need to correct the MAF table.
2. you should be using at least 91 octane. When knock occurs, the KR (knock retard) is immediately subtracted from the current running spark timing, and at the same time the PCM slides a weight toward the LO table, the weight is then used to calculate a weighted average between the HO and LO tables, and this becomes the new current running spark timing.
As short-term time progresses, the KR is decayed so that timing returns to the current running spark timing.
As long-term time progresses with no further knock, the PCM slides the weight back toward the HO table.
2. you should be using at least 91 octane. When knock occurs, the KR (knock retard) is immediately subtracted from the current running spark timing, and at the same time the PCM slides a weight toward the LO table, the weight is then used to calculate a weighted average between the HO and LO tables, and this becomes the new current running spark timing.
As short-term time progresses, the KR is decayed so that timing returns to the current running spark timing.
As long-term time progresses with no further knock, the PCM slides the weight back toward the HO table.
Thread Starter
Teching In
Joined: Mar 2016
Posts: 21
Likes: 0
Thanks Joecar.
I had , I thought, calibrated the maf frequency table. I used lt/st trims to build a data log and it did change my maf frequency table a little. It stayed nice and smooth so no hand blending was needed.
While thinking through the issue I brainstormed and multiplied my entire maf frequency table by 1.1 and relogged. It brought my trims in the -4/-5 range so I then multiplied the whole table by .95 and now my trims match with it in closed or open loop. Im not sure if its the proper way but everything is in check.
On the low high octaine tables, I was trying to tune for low octaine, im now back running 93.
Thanks for your response and time.
I had , I thought, calibrated the maf frequency table. I used lt/st trims to build a data log and it did change my maf frequency table a little. It stayed nice and smooth so no hand blending was needed.
While thinking through the issue I brainstormed and multiplied my entire maf frequency table by 1.1 and relogged. It brought my trims in the -4/-5 range so I then multiplied the whole table by .95 and now my trims match with it in closed or open loop. Im not sure if its the proper way but everything is in check.
On the low high octaine tables, I was trying to tune for low octaine, im now back running 93.
Thanks for your response and time.
