You have to understand what an “event” is. An event is the detection of knock on a particular cylinder firing (at least on the obd2 pcm’s), so if the engine is starting to knock, you get 3 events per revolution. 3000 rpm is 50 rev/sec, so you can potentially have 150 events per second at 3000 rpm. So, if it starts to knock, with the D4U1 pulling out 3.75* per event, it will quickly pull out however much its allowed to (based on the table of max retard due to the knock sensor) - usually around 10 degrees in the code that I’ve studied.
In general, Ford engineers think knock is to be avoided like the plague, and pull timing out 30-100 times faster than they return it.
On the other hand, GM engineers seem to like operating on the edge of knock, and (at least in the pcm’s that I’ve seen data on) pull out timing 2 times as fast as they put it back in.
On my Ranger, I re-shaped the tables to pull out knock 4 times as fast as it puts it back in (rather than 30x like the stock program was), and its much more driveable if I get some gas that’s shaky on the octane rating, but it still pulls out the timing quickly if it needs to.
The car now runs but the cams have completely thrown the tune off from the near perfection we had before the cams were installed. At first it was lean everywhere and would refuse to come off idle without a fight. We added 9% across the entire maf table and now we have low 12:1 AFR around 4K and it slowly leans out from 6K all the way to 8 where is it in the high 12:1. It might even touch low 13:1 . The car now pulls the same at 4500 as it does at 8K. These cams are fantastic! The car hits the limiter hard, but I am confident it has at least another 500rpm left before it runs out of potential. Now i’m a little disappointed that I didn’t port the heads on this engine like I had on my last one.
My only engine mods are stock heads + cams with stock timing gears and ported intake with big bore butterflies. I am only running 5psi because it is leaning out but on 5psi it pulls just as hard as it used to on 8. I can’t wait for 10psi!
you should richen that up to at least 12:1 in boost… id do 11.8. that little bit leaner doesnt get you much more power and has the ability to force you to be taking the engine out again.
it wasn’t set like that for the extra power. Something in the tuning software is being screwy and when we set it richer it was making it bog really bad down low. I might try a set of fresh spark plugs and see if that makes a improvement down low. After running it hard on the highway it has great low end response until everything cools down then it gets funky again. I am going to start with the simple things first before I play with the tune.
New sparkplugs
fix 1 exhaust leak before turbo
fix wastegate (does not close all the way)
the lean issue is the reason I have the car on 5psi. I figure on 5 psi a little bit lean isn’t going to hurt it. If i was still running 10 or 12 psi then it would concern me more, plus I’m not convinced that the exhaust leak isn’t giving a false wideband reading.
.020 . I was running .046 but was getting blowout over 10psi so I knocked it down to .035 and it was good. 5K later my copper plugs were dead. Now I am running plat plugs from a natural gas F150. These plugs come recommended a autolight engineer on SHOforum. It is what he runs in his turboSHO so if its good enough for him its good enough for me. He also recommended a .020 gap. They are also fine wire plugs.
honestly I think my problems are in the AFR and timing
lol .046 yeah i could see why youd be getting blowout/breakup. Ive seen guys with turbo hondas run stock ignitions to 600+ whp just changing the gap. Im running .024 ish but didnt have problems on the stock ignition with gaps as big as .034 ish
sometimes i wish i had my sho still.