Negative LTFT?
Burning Brakes
Joined: Aug 2010
Posts: 918
Likes: 47
From: Northborough MA
I believe you have too much fuel & timing. Like someone said, only + LTFT's get added to commanded, so you actually want a slight negative LTFT.
Looking at the injector pulse time, your at 95% plus(16.34@7k rpm). When I ran my car on stock injectors at 560/505 on a dynojet, my inj pulsewdith was 14.8@7k, with wideband in the X-pipe I had AFR at 12.4.
Are your knock sensor's desensitized at all? With that much extra fuel, you should not have any knock. And if you have knock on a dynojet, you certainly have it on the street!
If this was my car I would do this:
1. Run TR7ix, or similar heat range from Denso, forget if it is IT22 or IT24.
2. Adjust the timing down 2-3 degrees to start from 4.0K up til 6.5k.
3. Adjust Knock Sensor Initial & Min Level up by 50%.(Only if still set at OEM settings!!!)
4. Pull fuel out to get to 12.3-12.4 AFR.
Log it, and see how the car likes the timing. IF no knock, add 1 degree back at a time, until your not gaining at least 5whp. LS7's in NA trim are not gonna make a significant amount of power because you have another 2 degrees timing. The ones that run higher timing usually are running a slower burning fuel, like race gas. So they need to advance to just get back to where they were at on pump gas.
You didn't mention the fuel octane used, but I'm guessing 91? Which would further support the need for cooler plug, and reduced timing.
Looking at the injector pulse time, your at 95% plus(16.34@7k rpm). When I ran my car on stock injectors at 560/505 on a dynojet, my inj pulsewdith was 14.8@7k, with wideband in the X-pipe I had AFR at 12.4.
Are your knock sensor's desensitized at all? With that much extra fuel, you should not have any knock. And if you have knock on a dynojet, you certainly have it on the street!
If this was my car I would do this:
1. Run TR7ix, or similar heat range from Denso, forget if it is IT22 or IT24.
2. Adjust the timing down 2-3 degrees to start from 4.0K up til 6.5k.
3. Adjust Knock Sensor Initial & Min Level up by 50%.(Only if still set at OEM settings!!!)
4. Pull fuel out to get to 12.3-12.4 AFR.
Log it, and see how the car likes the timing. IF no knock, add 1 degree back at a time, until your not gaining at least 5whp. LS7's in NA trim are not gonna make a significant amount of power because you have another 2 degrees timing. The ones that run higher timing usually are running a slower burning fuel, like race gas. So they need to advance to just get back to where they were at on pump gas.
You didn't mention the fuel octane used, but I'm guessing 91? Which would further support the need for cooler plug, and reduced timing.
Thread Starter
Drifting
Joined: Jul 2007
Posts: 1,339
Likes: 245
From: Washington
I believe you have too much fuel & timing. Like someone said, only + LTFT's get added to commanded, so you actually want a slight negative LTFT.
Looking at the injector pulse time, your at 95% plus(16.34@7k rpm). When I ran my car on stock injectors at 560/505 on a dynojet, my inj pulsewdith was 14.8@7k, with wideband in the X-pipe I had AFR at 12.4.
Are your knock sensor's desensitized at all? With that much extra fuel, you should not have any knock. And if you have knock on a dynojet, you certainly have it on the street!
If this was my car I would do this:
1. Run TR7ix, or similar heat range from Denso, forget if it is IT22 or IT24.
2. Adjust the timing down 2-3 degrees to start from 4.0K up til 6.5k.
3. Adjust Knock Sensor Initial & Min Level up by 50%.(Only if still set at OEM settings!!!)
4. Pull fuel out to get to 12.3-12.4 AFR.
Log it, and see how the car likes the timing. IF no knock, add 1 degree back at a time, until your not gaining at least 5whp. LS7's in NA trim are not gonna make a significant amount of power because you have another 2 degrees timing. The ones that run higher timing usually are running a slower burning fuel, like race gas. So they need to advance to just get back to where they were at on pump gas.
You didn't mention the fuel octane used, but I'm guessing 91? Which would further support the need for cooler plug, and reduced timing.
Looking at the injector pulse time, your at 95% plus(16.34@7k rpm). When I ran my car on stock injectors at 560/505 on a dynojet, my inj pulsewdith was 14.8@7k, with wideband in the X-pipe I had AFR at 12.4.
Are your knock sensor's desensitized at all? With that much extra fuel, you should not have any knock. And if you have knock on a dynojet, you certainly have it on the street!
If this was my car I would do this:
1. Run TR7ix, or similar heat range from Denso, forget if it is IT22 or IT24.
2. Adjust the timing down 2-3 degrees to start from 4.0K up til 6.5k.
3. Adjust Knock Sensor Initial & Min Level up by 50%.(Only if still set at OEM settings!!!)
4. Pull fuel out to get to 12.3-12.4 AFR.
Log it, and see how the car likes the timing. IF no knock, add 1 degree back at a time, until your not gaining at least 5whp. LS7's in NA trim are not gonna make a significant amount of power because you have another 2 degrees timing. The ones that run higher timing usually are running a slower burning fuel, like race gas. So they need to advance to just get back to where they were at on pump gas.
You didn't mention the fuel octane used, but I'm guessing 91? Which would further support the need for cooler plug, and reduced timing.
I just got hptuners like 2 weeks ago and haven't had much time to really dive into it. Tuner is sending me a config file next week to log into once I get the wideband hooked up, so hopefully he can see something right away. The car ran great at the initial tune and wasnt as rich as the second dyno. There was obvious smoke and more of a rich smell on the 538whp dyno.
Burning Brakes
Joined: Aug 2010
Posts: 918
Likes: 47
From: Northborough MA
You will want to add cyl/air mass to your log, most histogram/graphs use that as the row axis, to plot what the pcm is doing for timing, knock retard,etc...
Also, in the knock sensor adjustments, you will want to ramp up, more aggressive, Knock Retard Decay Rate. I have mine set a lot higher than the really low stock tables (In peak knock zone, 4-5.5k, mine is 10x higher). This allows the pcm to put back the timing in the absence of knock faster.
Having that table aggressive, pretty easily identifies false knock. So if you had something triggering the knock sensors falsely, it would take away timing momentarily, and then give it right back. Had it been real knock, it would not go away for at least a few hundred rpm. Of course, if you have higher octane fuel available, splash some in, and confirm either the it still there, false knock, or gone away REAL knock.
High Octane Spark, and as far as fuel, since you are commanding .85 lambda, the target afr is good. So it is the MAF transfer table(s) that need tweaking. I would start with seeing what the LTFT's are for each given range in the MAF, and apply 50% of the correction.
So, if you have LTFT's of -6% in the 6000-6500mhz area, I would reduce the g/sec airflow value by -3%. Then reset your trims, and drive around and see where they drift towards. Rinse & repeat as needed to get your LTFT's under 5%, or if your OCD, then under 3%.
Definitely need a wideband for the WOT AFR, narrowbands are just not that accurate below 13:1.
Finally, you paid a pro tuner, let them tweak the tune, and let them know if you have changed anything in the tune!!! OR keep their copy of the tune as you tweak your own version. Then you can compare who's results are better!
Also, in the knock sensor adjustments, you will want to ramp up, more aggressive, Knock Retard Decay Rate. I have mine set a lot higher than the really low stock tables (In peak knock zone, 4-5.5k, mine is 10x higher). This allows the pcm to put back the timing in the absence of knock faster.
Having that table aggressive, pretty easily identifies false knock. So if you had something triggering the knock sensors falsely, it would take away timing momentarily, and then give it right back. Had it been real knock, it would not go away for at least a few hundred rpm. Of course, if you have higher octane fuel available, splash some in, and confirm either the it still there, false knock, or gone away REAL knock.
High Octane Spark, and as far as fuel, since you are commanding .85 lambda, the target afr is good. So it is the MAF transfer table(s) that need tweaking. I would start with seeing what the LTFT's are for each given range in the MAF, and apply 50% of the correction.
So, if you have LTFT's of -6% in the 6000-6500mhz area, I would reduce the g/sec airflow value by -3%. Then reset your trims, and drive around and see where they drift towards. Rinse & repeat as needed to get your LTFT's under 5%, or if your OCD, then under 3%.
Definitely need a wideband for the WOT AFR, narrowbands are just not that accurate below 13:1.
Finally, you paid a pro tuner, let them tweak the tune, and let them know if you have changed anything in the tune!!! OR keep their copy of the tune as you tweak your own version. Then you can compare who's results are better!
