Part throttle knock (ATI)
Part throttle knock (ATI) Ok,
Thought I was doing pretty good on the tuning so far, but ran in to a problem today.
IFR 170% across the board
PE vs. RPM 2000 to 3600 +4%, 4000 to 7200 +6%
VE untouched
LTerms:
Load around -5.5
Idle around -1.6
Zeroing out at WOT
While running around today, logging LTerms to see if the 170 value is working out, I hit it a couple times. WOT seemed fine... intermittant negligible knock (< .5), which I've had even pre-SC. Anyway, I put it in third and gave it more than normal throttle, but less than WOT and felt it die... looked at the laptop and saw a knock spike of 11.x <--- dangerous territory. Unfortunately, I wasnt logging at the time. I have the timing dropped pretty good right now(16) but I still have some higher values around the .4g/cyl range. Think I should drop the timing more in the lower values? I could take it out and try to recreate it to get the g/cyl and rpm it occuring at but I definitely dont want to drop a piston just to find out where the problem is.
(EDITED)Also IATs are good, so I dont think thats a problem
Anyone have any suggestions.
Thought I was doing pretty good on the tuning so far, but ran in to a problem today.
IFR 170% across the board
PE vs. RPM 2000 to 3600 +4%, 4000 to 7200 +6%
VE untouched
LTerms:
Load around -5.5
Idle around -1.6
Zeroing out at WOT
While running around today, logging LTerms to see if the 170 value is working out, I hit it a couple times. WOT seemed fine... intermittant negligible knock (< .5), which I've had even pre-SC. Anyway, I put it in third and gave it more than normal throttle, but less than WOT and felt it die... looked at the laptop and saw a knock spike of 11.x <--- dangerous territory. Unfortunately, I wasnt logging at the time. I have the timing dropped pretty good right now(16) but I still have some higher values around the .4g/cyl range. Think I should drop the timing more in the lower values? I could take it out and try to recreate it to get the g/cyl and rpm it occuring at but I definitely dont want to drop a piston just to find out where the problem is.
(EDITED)Also IATs are good, so I dont think thats a problem
Anyone have any suggestions.
Re: Part throttle knock (ATI) Maybe you were only showing enough TPS that the
computer was still trying to do closed loop? At
low / mid speed a partial throttle opening is
still enough for strong cylinder filling but may
not trigger WOT behavior.
Something like that "TPS Enhancer", or its soft
equivalent, may be what you need - to get the
closed loop to give up and open loop tuning (that
you get to call the shots) to happen at low
enough blade angle that nobody gets hurt. That
angle is gonna be lower on a force fed motor.
I'd say you want to have closed loop up to whatever
blade angle will let you cruise at 85 on the highway,
and fool it into letting you have your own tune at
any higher blade angle.
computer was still trying to do closed loop? At
low / mid speed a partial throttle opening is
still enough for strong cylinder filling but may
not trigger WOT behavior.
Something like that "TPS Enhancer", or its soft
equivalent, may be what you need - to get the
closed loop to give up and open loop tuning (that
you get to call the shots) to happen at low
enough blade angle that nobody gets hurt. That
angle is gonna be lower on a force fed motor.
I'd say you want to have closed loop up to whatever
blade angle will let you cruise at 85 on the highway,
and fool it into letting you have your own tune at
any higher blade angle.
Re: Part throttle knock (ATI) I don't know that this would work; if the PCM
still "thinks" it should be in closed loop, it
will learn out whatever you do to PE that
"touches" a closed-loop cell. Then, you are at
14.7(ish) all over again, with a different fuel
trim but the same high cylinder pressure.
Need some "handle" that tells it, like, WOT /
non-closed-loop is TPS>2V instead of TPS>4V
(or whatever). Then your PE is what you say it is,
not what you say it is plus LTFT.
Does this make sense?
still "thinks" it should be in closed loop, it
will learn out whatever you do to PE that
"touches" a closed-loop cell. Then, you are at
14.7(ish) all over again, with a different fuel
trim but the same high cylinder pressure.
Need some "handle" that tells it, like, WOT /
non-closed-loop is TPS>2V instead of TPS>4V
(or whatever). Then your PE is what you say it is,
not what you say it is plus LTFT.
Does this make sense?
Re: Part throttle knock (ATI) Yes, but in edit, the WOT Hot/Cold settings tell the PCM to enter WOT at x rpm if the throttle position is >= the percentage in the table. So if I were to lower the percentage a few points, this would enable PE at a lower TPA. If the criteria is met, the PCM wont have to "think" about anything. It will be in open loop.
Re: Part throttle knock (ATI) Note: if the PCM senses knock under given parameters it will pull alot of timing. The amount of retard does not mean the severity of knock. This does not mean that there was alot of spk knock it could just bit a very small amount. If you have a knock and it knocks again while the KR is decaying then you have a problem and should retard where the latter knock occured. EG spk @ .4gmscyl and 2400 rpm -11 deg then as the value is returning to 0 KR and then spk knock @.4 2400 while the KR value is still @ 3 you then need to retard 3deg but high values in the Max retard is not necessary. If it were me I would just retard a bit of timing within the cell and leave all else alone.
Jeremy Formato
Jeremy Formato
