Ryoko

Let's go truly hardcore and hack into an ECM. I'm trying to get some info on the TPC8101 knock sensor interface chip. Has anyone played with one of these on a DIY EFI build? The specs don't provide any guidance for real world settings.

Che70velle

iTrader: (6)

Exactly what are you looking for here?

Ryoko

The questions have to do with the period used for the integration and whether the period varies with RPM. The other question is since the device can listen to only one knock sensor at a time, how does it determine which one to listen to?

TrendSetter

that chip has been used with megasquirt. have you looked at the source/tunes that utilize it? there might be some good info there.

Ryoko

I took your suggesting and skimmed thru the MS3 code. (I didn't know it was on GitHub.) It seems they are using just one of the knock sensor channels. However, that conclusion was based on a rather quick review of the code, so I may have missed something.

pantera_efi

iTrader: (1)

Hi Ryoko, I am not much of a DIY but more of a manufacturer of EMS as the inventor of modern DIS in the 1980's using the 60-2 TW for crankshaft position decode AND acceleration measurement.

THUS I use crankshaft acceleration measurement for Knock Detection.

I did measure my work with TWO Piezo sensors, engine mounted, finding NOISE as EQUAL in crankshaft position AND Knock Detection at DIFFERENT Positions.

The Differential Piezo AMP does by nature of circuit design.

Those who fit my IGN-1A-LS coil kit can use ION Sensing as does Woodward for Knock Detection.

Lance.

Ryoko

Interesting idea using the crank acceleration to detect a knock condition. But I don't think the 24T cks has enough resolution to do that reliably. The target engine I'm toying with applying this to is the LQ4. I was considering stroking it, so I'm tempted to go with the 58T wheel when replacing the crank since it provides better feedback and doesn't have the screwy signal pattern the like 24T has.

It would be nice to use an ion system. But I'm trying to stay with stock items as much as possible and adapting the coil modules to support ion measurement isn't really an option.

pantera_efi

iTrader: (1)

Hi Ryoko, you are one of FEW here that understand the difference between a 24 tooth TW and a 60 tooth TW.

The math supports a 1/4 degree position resolution at a 2500 RPM Acceleration Rate WHEN a 60-2 ( GM 58x) TW is fitted.
The math supports a 1-2 degree position resolution at a 2500 RPM Acceleration Rate WHEN a 24 (GM24xe) TW is fitted.

THUS when the engine increases RPM there can be a TWO Degree timing Retard with the 24xe
THUS when the engine "drops" RPM as in an up-shift there can be a
TWO Degree ADVANCE in the Spark Instant, yes full at Boost/NOS, at WOT.

The task of measurement is easy when tooth timers are used, I do the measurement twelve times between each tooth.

Coil Dwell changes MUCH greater with a 24 tooth TW when the engine accelerates.

YES fit the 58x AND the GRAY Crank Sensor.

Lance

Ryoko

Hard shifts and/or drive line shocks would concern me as being misinterpreted as an engine knock. For example a violent upshift or rear wheel chatter would transmit shocks back to the crank which could possibly be seen as a knock if looking only at the crank angular acceleration. I'm not sure how effective the clutch plate springs would be to prevent a false positive. (Clutch chatter is another possible issue, albeit that's a mechanical problem in its own right.) I'll assume there's enough torsional flex in the driveshaft to absorb the worst of a tire chatter condition.

pantera_efi

iTrader: (1)

Hi Ryoko, again good tech on your part.

I have done MANY Rolling Road tests.
MY METHOD is to turn OFF the smoothing filters for the data seen at the Rollers.
THUS the report has "miss-fire" information easily seen in the created graphs.
This data report of crankshaft acceleration travels through the trans, drive line, diff, tries, etc.
The graph BECOMES a line with many small peaks and valleys when miss-fire occurs. (^_^_^_)

The MAIN REASON OEM's liked the 60-2 TW was the resistance to STOP the CE light miss read caused when a car crossed R/R tracks, pot holes, other read hazards.

TO answer your question MORE DIRECT is to share the "sample window" position read in crankshaft degrees method or that the read NEEDS to be in the combustion window OR at max piston pressure NOT an averaged pressure.
This is another type of filter used to rule out a Miss-Read.

Lance