At what RPM do you guys turn off the knock sensors to avoid the normal engine interference?
TEC-3R, T4 GT40, WISECO, EAGLE, SUPERTECH, O-RING'D "FRANKENSTEIN" STROKER.
never turn them off
1998 Turbo M3 Nick G tuned setting 5 934Whp 849Wtq @27.88 Psi. ignite E90 setting 6=
I thought that too.
However, from 4000-6000 rpm I can watch my knock sensor voltage move from .0-5.0v with no actual knock registering on the datalog. This is on e85 and 15psi with 17 degrees timing.
At 6000 rpm when the sensor is at 5v the EMU pulls timing and shuts down the car.
I read this tuning guide and it's got me thinking.
KNOCK SENSORS.PNG
TEC-3R, T4 GT40, WISECO, EAGLE, SUPERTECH, O-RING'D "FRANKENSTEIN" STROKER.
Welcome to our primitive knock sensors
If you intend to use knock sensing up high our blocks are just not good for it. There is a lot of filtering considerations and more modern ECUs are aware of cylinder timing and such or use DSP.
Digital sound processing - some standalones will filter the signal more liberally than others. Factory DMEs know exactly the freq to target and with modern processing can target the time window to look at - per cylinder knock. They know when the detonation could occur vs. ordinary detonation so no use just objectively "listening".
The best solution is ion sensing. Very fascinating if you haven't researched it. Unfortunately, I can't say I have ever come across a perfect solution - even factory my car will pull some timing based on false knock.
I'd say something is wrong somewhere as that isn't normal - if you have a TEC3R like it says in your sig. then the first step would be to toss that door stop of an ECU in the trash and move to something from this past century along with checking/replacing the knock sensors and wiring, and making sure the knock sensors are torqued to spec.
Last edited by trthrrt489; 09-08-2022 at 03:10 PM.
TEC-3R, T4 GT40, WISECO, EAGLE, SUPERTECH, O-RING'D "FRANKENSTEIN" STROKER.
SAAB did this with their Trionic EMS. They could tell AFR, knock, burn rate, misfire, and all by applying a high V across the plug gap, post ignition. The ignition coil cartridge was a nice bit of tech with self-contained CDI, but the 'in joke' amongst SAAB owners was how we all kept a spare cartridge in the trunk!
1989 E30 - M50B28 Turbo - ZF 8 Speed
BMW used ionic knock sensing on the S65 in the E90 M3 and the S85 in the E60 M5, but I don’t think they used it in any other motors. If it is so good, why doesn’t BMW still use it?
The Bosch wideband knock sensors work great just be sure to use them with a good coax shielded harness to ensure the ecu is getting a nice clean signal. I always recommend the VE wideband knock kit for cars I’m tuning as it comes with a coax harness you just pin straight to the ecu.
IMO Motec M1 ecu’s have the most elegant closed loop knock strategies.
Last edited by tunermt; 09-25-2022 at 07:52 AM.
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