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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?
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
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
Thanks, been doing that. Without much success. Latest log shows 2 Knk's @ 90KPAs, 60% TPS, 2000 RPM's, and 1 @ 95 KPAs 4000 RPM's and @ 4400 RPMs both @ WOT. High KPA AFR's in low 11's - I'll lean those and see what happens. Cruise AFR's run rich sometimes and near stoich at others - can't put my finger on why yet...
You also really have to focus on what the engine wants, not what you think it needs. I know my LT383 is a thirsty b1tch. It's not happy unless it's in the 13.6-14.0 range. Even at idle. Any leaner and it chugs and runs like poo
Take pics of the actually graphs themselves. Even then, you're running WAY too much timing for a cam that small. 45 degrees advanced is playing with fire.
Take pics of the actually graphs themselves. Even then, you're running WAY too much timing for a cam that small. 45 degrees advanced is playing with fire.
These? Thanks, I've been looking for this type of feedback.... Hopefully the engine hasn't spent much time in those "playing with fire" areas. I'm not getting a lot of knocks... Recommendations?
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.
"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.
"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.
I'm not adding SA. I'm retarding it and have been.
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.
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).
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.
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.
"Rich Knock" interesting... actually I'll be doing exactly what you suggested. If it is a rich knock it should go away then . I'm thinking it's a false based on my analysis - see comments above but also think I'm going to hit it with some seafoam to clear potential it's not carbon hot spots causing detonation. Been told to check torque on knock sensor also. Thanks for sharing info...
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. ?
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
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
I guess short of a Dyno the only way to adjust SA is by feel. Your AFR at what kpa is 13.5 - 14? Seems I need 11& 12's when I get into higher kpa's like 80 to 100.
08-18-2018, 01:49 PM
