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I tune today a honda civic d16 turbo engine at 9psi with 93oct fuel... And no matter what i did the plex knock monitor graph was all over the place detecting knocking i retard, advance, lean, rich the AFR and still doing the dame i used the advance setting with the trigger reading RPMS... I try the 75mm frequency of 7k and 15k.. The graph on the dyno was sloppy so i decide to forget about the knock monitor and do what i used to do and the graph get fine and smooth... Someone have this issue with the Plex?
This isn't a problem I've struck with the Plex before. The fact that you've got knock counts at 11,000 rpm suggests there is something going on with the rpm input to the Plex though so I'd start by checking this. It may also be worth adjusting the gain to reduce the signal level from the knock sensor. What does the engine sound like using the audio detection? Can you audibly hear knock when it occurs? Lastly, where have you got the sensor mounted?
Hey Andre Thanks for the fast response... i couldn't hear any knock from outside the engine but with the headphones yes... i put the engine in 5th gear and advance the timing around 1500 to 2000 rpm to get a taste of how was supposed to sound first...... With the headphones filters at 7k or 8k at high rpms between 4800 to 5500, 7 to 8psi with 12 to 14 degrees i could hear the sound..... the sensor was mounted in a tap that i found between cyl 3 and 4 in the middle of the engine under the exhaust manifold... the 11k RPM count its probably when the ecu did the ignition cut im grabbing the signal from the tach output... i didn't wanted to play with the sensor gain because i'm not really sure how it work
You can find information on how to set the gain in the online manual you'll find here: https://www.plex-tuning.com/instructions/KNOCK_Instructions_V2/Knock_Monitor_Instructions_Manual_V2.0.html?Help.html
Basically you want to adjust the gain until you're seeing values between 80-100 peak with no knock present. It's just occurred to me though, have you set a background noise threshold vs rpm in the Plex?