What to datalog?

Jörgen Karlsson jurg at pp.sbbs.se
Sat Jul 8 04:13:47 GMT 2000


> I would recommend adding throttle position, fuel pressure, RPM and spark
> advance. Those four would do a LOT toward helping you correlate your EGT
> readings.

I have been thinking of throttle position but decided that I dont have much
use of it, the engine management is almost 100% based on manifold pressure.
But it looks like I might include it anyway, yesterday I was looking at some
speedpro logs that didn't have tps included, it was hard to see if the
driver really had floored it. It is also useful for syncronizing with the
log from my ecu.

I do log RPM, spark advance would require logging the hall sensor in the
distributor and when the ecu really fires it up, I think that this will take
up to much processing power compared to the value of the info. As long as
the MAP, RPM and tps in the ECU log and my log are in par the advance will
be known already. But it will of course help me to pull the timing from the
stock computer and I know an other guy that also gets one of these and he
could use it. I think that I will have to take a look at it...

A log of the fuel pressure sounds more and more useful, I am thinking of how
bad a car can run without the fuel pressure gauge shows any problems.

> Nice to have's would include oil temp (Pre/post turbo?), oil
> pressure,

I am thinking of an alternative display mode where oil pressure, oil temp,
fuel pressure, intake temp and maybe a two others are shown. I have room for
twelve readings on the display, six with explaining text.

The standard display mode has all TC readings, timestamp, rpm and boost, it
is primarily made for egt measurement.

> wideband 02 might be nice for an additional correlation for the
> EGT readings.

I get a log of the O2 from the ecu, but it could be nice to log it without
having the laptop plugged in and it leaves the field open for EGOR.

> Maybe add driveshaft RPM to use with engine RPM to calculate
> tranny/clutch slippage.

I have been thinking of sensors on all four wheels(AWD), I just have to tap
into the ABS sensors, but that will be much later.


> How big are your thermocouples?

The tip of the probe are around 1/8 of an inch, no exposed tip;)

>Will the manufacturer give you
> the response
> curve? I believe they are rated in microvolts/millisecond for
> response time.

I don't think that I can get that from them.

> That would let you know your fastest effective sample rate.

I don't know if that is true, I was thinking something like: the higher
resolution and the higher samplerate the better the chance is to detect a
detonation on a slow probe. This is only an experiment, I want to see if it
works. But I know a few guys over here that wants the EGT part of the system
for their V8 racers, they can use the fast probes since they don't use
turbos. They want the high sample rate, eight egt's and rpm. No external adc
in their case.

Jörgen

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