Open Loop Tuning - Chasing Knocks
#1
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Open Loop Tuning - Chasing Knocks
Running a 383 Aluminum Head Stroker... Crossfire with Renegade... mild cam upgrade ... 80# inj @ 24 psi, Variable FP Regulator
VE tables coming together and it's running pretty strong... Currently running VE learns in open loop and trying to eliminate some knocks.
I've been Chasing knocks by throwing more fuel at "em without much success. Then after studying the data analysis log closer it appears the knocks occur when things transition quickly from cruise (~14.7 AFR - KPA's ~40) to a higher loads with KPA's around 80-95. Within less than a second things richen up and because I'v been throwing fuel at it go too rich ~9/10's.
So - should I richen things up at cruise (even though learns are telling me something different) and then lean things up a bit in the high KPA areas? Anyone experience this and correct it like I suggested?
VE tables coming together and it's running pretty strong... Currently running VE learns in open loop and trying to eliminate some knocks.
I've been Chasing knocks by throwing more fuel at "em without much success. Then after studying the data analysis log closer it appears the knocks occur when things transition quickly from cruise (~14.7 AFR - KPA's ~40) to a higher loads with KPA's around 80-95. Within less than a second things richen up and because I'v been throwing fuel at it go too rich ~9/10's.
So - should I richen things up at cruise (even though learns are telling me something different) and then lean things up a bit in the high KPA areas? Anyone experience this and correct it like I suggested?
#2
Re: Open Loop Tuning - Chasing Knocks
Do some datalogs and look at the areas that need to be adjusted. Then add or subtract the VE tables in those areas. I believe in open loop all that's being read is the commanded afr open loop tables and the VE tables. Someone can correct me if I'm wrong. I'm kinda in the same boat with my LT383 lol
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Re: Open Loop Tuning - Chasing Knocks
How about using less timing advance... ?
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#5
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Re: Open Loop Tuning - Chasing Knocks
Do some datalogs and look at the areas that need to be adjusted. Then add or subtract the VE tables in those areas. I believe in open loop all that's being read is the commanded afr open loop tables and the VE tables. Someone can correct me if I'm wrong. I'm kinda in the same boat with my LT383 lol
#6
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Re: Open Loop Tuning - Chasing Knocks
So if EBL WUD SPK screen is showing me 2* spark retard on knock is that what I should adjust SA by (2*)?
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Re: Open Loop Tuning - Chasing Knocks
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Re: Open Loop Tuning - Chasing Knocks
#14
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Re: Open Loop Tuning - Chasing Knocks
OK smoothed SA table - here's my knock counts. Should I be concerned?
#15
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Re: Open Loop Tuning - Chasing Knocks
For kicks I dropped SA 3* in the knock areas and got more knocks??? Go figure....
#16
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Re: Open Loop Tuning - Chasing Knocks
Dropping SA and it doesn't seem to be losing power now. Going to continue to play with this. Still getting some knocks. Engine set at 8* BTDC and below is my latest SA table. To me (certified amateur) SA's look low but this may be the answer. They look low to anyone else???? Knocks at these setting shown also below.
#17
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Re: Open Loop Tuning - Chasing Knocks
Finding this... it's leaning itself out. Not enough AE?
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Re: Open Loop Tuning - Chasing Knocks
"Knock" at its most basic level is an ignition event happening at the wrong time.
1. You told it to ignite early by commanding too much spark advance.
2. Hot spots in the cylinder that are so hot that it auto-ignites the fuel.
As you continue to increase spark advance the engine will initially respond with more torque, then performance flattens out, and then the engine starts to lose power, and finally when you've pushed it waaaaay too far you'll get knock. There's no need to add any more spark advance than when the performance begins to flatten out.
1. You told it to ignite early by commanding too much spark advance.
2. Hot spots in the cylinder that are so hot that it auto-ignites the fuel.
As you continue to increase spark advance the engine will initially respond with more torque, then performance flattens out, and then the engine starts to lose power, and finally when you've pushed it waaaaay too far you'll get knock. There's no need to add any more spark advance than when the performance begins to flatten out.
#19
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Re: Open Loop Tuning - Chasing Knocks
"Knock" at its most basic level is an ignition event happening at the wrong time.
1. You told it to ignite early by commanding too much spark advance.
2. Hot spots in the cylinder that are so hot that it auto-ignites the fuel.
As you continue to increase spark advance the engine will initially respond with more torque, then performance flattens out, and then the engine starts to lose power, and finally when you've pushed it waaaaay too far you'll get knock. There's no need to add any more spark advance than when the performance begins to flatten out.
1. You told it to ignite early by commanding too much spark advance.
2. Hot spots in the cylinder that are so hot that it auto-ignites the fuel.
As you continue to increase spark advance the engine will initially respond with more torque, then performance flattens out, and then the engine starts to lose power, and finally when you've pushed it waaaaay too far you'll get knock. There's no need to add any more spark advance than when the performance begins to flatten out.
#20
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Re: Open Loop Tuning - Chasing Knocks
I dumped the data log and found more precisely when it's knocking. It's not at the lean spike but just before it. Found that in a couple of cases and I'm also finding cases where there's no leaning and I'm getting significant knock.Knocks occurring where AFR's are in the 10' and 11's and SA's (i.e. initial SA + SA) are 25* or less. I'm beginning to believe my plugs are too hot or carbon laden pistons are creating hot spots causing detonation.
Last edited by Cartrax; 08-23-2018 at 12:59 PM.
#21
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Re: Open Loop Tuning - Chasing Knocks
Threw a set of colder plugs in still knocking some. Could very well be false knocks.
Real knocks are supposed to get worse the longer your are on the throttle. Mine kick in a couple of seconds after 100% TPS and after a second or so go away while TPS is still @100% for a long as 5 seconds.
Real knocks are supposed tone down after SA retarding and fuel richening - haven't seen that.
Under same exact KPA, RPM, SA, AFR conditions where knocks are noted I noted no knocking at all.
Plugs are hard to read because of carbon but I didn't see any sign of detonation (silver or black specs).
So I'm think false knocks - I hope so...
Real knocks are supposed to get worse the longer your are on the throttle. Mine kick in a couple of seconds after 100% TPS and after a second or so go away while TPS is still @100% for a long as 5 seconds.
Real knocks are supposed tone down after SA retarding and fuel richening - haven't seen that.
Under same exact KPA, RPM, SA, AFR conditions where knocks are noted I noted no knocking at all.
Plugs are hard to read because of carbon but I didn't see any sign of detonation (silver or black specs).
So I'm think false knocks - I hope so...
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Re: Open Loop Tuning - Chasing Knocks
I chased knocking with my car for years. I run a v6 with a turbo so knocking under boost is even more critical. I thought to get rid of it all I needed to do was to retard timing or add more fuel in those areas. Turned out the knocking was caused by rich knock. I started to pull fuel out a little at a time and found the sweet spot. Once the knocking was gone, I was able to add more timing. You also said your plugs are hard to read because of carbon which tells me you are too rich. I would go back to the stock heat range and pull a little fuel then read the plugs.
#23
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Re: Open Loop Tuning - Chasing Knocks
I chased knocking with my car for years. I run a v6 with a turbo so knocking under boost is even more critical. I thought to get rid of it all I needed to do was to retard timing or add more fuel in those areas. Turned out the knocking was caused by rich knock. I started to pull fuel out a little at a time and found the sweet spot. Once the knocking was gone, I was able to add more timing. You also said your plugs are hard to read because of carbon which tells me you are too rich. I would go back to the stock heat range and pull a little fuel then read the plugs.
#24
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Re: Open Loop Tuning - Chasing Knocks
Well, well, well... Knocks were REAL... No I didn't blow it up but I'm surprised I didn't. Here's what it took. Seafoam treatment this AM and playing with the SA tables. I added 20% across the board knocked everywhere. Then cut 50% SA from pre 20% tables = No Knocks! Anywhere!
Played with SA tables prior to seafoam treatment but results were mixed - must have been carbon hot spots giving me detonation. Anyway, now need to work back some SA slowly... I think. Maybe I should take it to a dyno. ?
BTW - doesn't run worse with lower SA's.
Played with SA tables prior to seafoam treatment but results were mixed - must have been carbon hot spots giving me detonation. Anyway, now need to work back some SA slowly... I think. Maybe I should take it to a dyno. ?
BTW - doesn't run worse with lower SA's.
#25
Re: Open Loop Tuning - Chasing Knocks
I actually played with my SA tables today myself. I've always felt a soft spot in the 2000-3500 rpm range so I rose my SA about 10-15 percent in that range and in my 40-60 map which made a HUGE difference in throttle response and torque. My AFR sits around 13.5-14.0 which seems to be good
#26
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Re: Open Loop Tuning - Chasing Knocks
I actually played with my SA tables today myself. I've always felt a soft spot in the 2000-3500 rpm range so I rose my SA about 10-15 percent in that range and in my 40-60 map which made a HUGE difference in throttle response and torque. My AFR sits around 13.5-14.0 which seems to be good
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