KR on WOT transistion
Thread Starter
Teching In
Joined: May 2005
Posts: 45
Likes: 0
From: Allen, Texas
KR on WOT transistion I am getting KR sometimes when I go from partial throttle to WOT. I've attached a chart of the worst case I've seen so far. About 3/4 of a second after the WOT transition, just as the engine speed starts to increase rapidly, I get several KR events.
I just installed a meth/water spray, and haven't seen ANY KR on the 1/4 test runs I have made, only when driving along and then gun it.
I'm still working with my spark advance... reading up on "what is right" as I experiment a little at a time. I am looking for advice on how to tackle this issue. Should I automatically lower the timing numbers in the range where this occurred? Or could it be related to something else? Why would I be getting KR only after a partial to WOT transition and not when I start from a standstill?
I just installed a meth/water spray, and haven't seen ANY KR on the 1/4 test runs I have made, only when driving along and then gun it.
I'm still working with my spark advance... reading up on "what is right" as I experiment a little at a time. I am looking for advice on how to tackle this issue. Should I automatically lower the timing numbers in the range where this occurred? Or could it be related to something else? Why would I be getting KR only after a partial to WOT transition and not when I start from a standstill?
Perhaps this has to do with a 8PSI blower and a 1-bar MAP sensor.
Whenever you are unsteady MAP or TPS the PCM goes back to
speed density mode for a bit. With your MAP sensor clipping at
103kPa you are not using a true manifold pressure for airflow and
fuel shot calculations, all bets are off, you have to wait for the
MAF to come around and fake the PE, right? Only that may not be
so consistent with the weather and so on.
On the track your speed-density interval is spent back at the line
where you don't have boost built and don't have the traction to
really load up the motor.
The question is, what does your wideband show for AFR right before
the KR hits. That line is not showing on your picture. Also trucks
tend to hold off PE some and this would not be helping, dunno if you
have already fixed that.
Whenever you are unsteady MAP or TPS the PCM goes back to
speed density mode for a bit. With your MAP sensor clipping at
103kPa you are not using a true manifold pressure for airflow and
fuel shot calculations, all bets are off, you have to wait for the
MAF to come around and fake the PE, right? Only that may not be
so consistent with the weather and so on.
On the track your speed-density interval is spent back at the line
where you don't have boost built and don't have the traction to
really load up the motor.
The question is, what does your wideband show for AFR right before
the KR hits. That line is not showing on your picture. Also trucks
tend to hold off PE some and this would not be helping, dunno if you
have already fixed that.
Thread Starter
Teching In
Joined: May 2005
Posts: 45
Likes: 0
From: Allen, Texas
Your explanation sounds good to me. I wasn't thinking along those lines, so this helps me out, thanks. This may be one of the reasons to change to the 2-bar tune.
I just installed the wideband, and don't have the EIO interface on my HP tuners, so I'll need to do some more testing to figure out what the AFR is right before the KR is occurring. I just saw the post that explains how to use the VCM's EGR or A/C pressure input for a wideband... I think I might go that route instead of upgrading my HP tuners. I guess knowing the AFR is the only way to really tell if the problem is related to fuel, so I'll get to work on that. The only other option is timing, right?
I do remember when I first added the supercharger finally figuring out that my "enrichment rate" was set too low... if I remember it was a number like 0.1. I currently have it set to 1.0, but notice that the max is 4.0. Having this number set too low would cause "hold off of PE", correct? Would increasing it further be recommended?
I just installed the wideband, and don't have the EIO interface on my HP tuners, so I'll need to do some more testing to figure out what the AFR is right before the KR is occurring. I just saw the post that explains how to use the VCM's EGR or A/C pressure input for a wideband... I think I might go that route instead of upgrading my HP tuners. I guess knowing the AFR is the only way to really tell if the problem is related to fuel, so I'll get to work on that. The only other option is timing, right?
I do remember when I first added the supercharger finally figuring out that my "enrichment rate" was set too low... if I remember it was a number like 0.1. I currently have it set to 1.0, but notice that the max is 4.0. Having this number set too low would cause "hold off of PE", correct? Would increasing it further be recommended?
1.0 is good enough, that's "do it now". Look for a PE mode delay
as well and zero it.
Speaking of timing, trucks can have a messy burst knock setup.
But this should only pull timing and not show as KR. I have seen
this really mess with a truck's ability to run up RPM in 1st gear,
the burst knock holds it back. 0.010 threshold is too low, 0.020
seemed good enough on a mildly cammed 5.3; log your various
spark retard PIDs and see if any besides KR are busy.
as well and zero it.
Speaking of timing, trucks can have a messy burst knock setup.
But this should only pull timing and not show as KR. I have seen
this really mess with a truck's ability to run up RPM in 1st gear,
the burst knock holds it back. 0.010 threshold is too low, 0.020
seemed good enough on a mildly cammed 5.3; log your various
spark retard PIDs and see if any besides KR are busy.
Thread Starter
Teching In
Joined: May 2005
Posts: 45
Likes: 0
From: Allen, Texas
I ran across "WOT Entry Max Airflow" enable|disable under the airflow/dynamic menu. It is currently disabled, but I am thinking this sounds like a good thing. Any reason not to turn it on?
Also, right below it is the MAP/TPS Airflow Filter... according to the help file this "is also used to filter the MAF airmass when the engine RPM is greater than the High RPM Disable limit" (currently set to 4000 rpm). So, a filtered setting causes a "lag" response to the MAF sensor, right? Would this be to prevent instability? My current setting is 0.1016
Also, right below it is the MAP/TPS Airflow Filter... according to the help file this "is also used to filter the MAF airmass when the engine RPM is greater than the High RPM Disable limit" (currently set to 4000 rpm). So, a filtered setting causes a "lag" response to the MAF sensor, right? Would this be to prevent instability? My current setting is 0.1016
