Z22SE water temp reverse engineering (VX220 only?)

nickb777

rik1083 said:

alanoo said:
It won't

:yeahthat:

🙁 wonder if I can get the scangauge to keep on working?

alanoo

Another no 🙂

rik1083

no scanguage, but what would you use that for? just plug in laptop to the rs232 on the s40 and see everything 🙂

alanoo

Well, as there's now quite a few ITB/standalone powered Z22SE's, there may be some interest to look into this a bit further notsure.gif

rik1083

if 5 people put their name down for one at £30 a go that might give me a bit more incentive 🙂

vocky

every itb owner would buy one :thumbup:

I would take one for £30 😃

alanoo

Yep I would too 😃

slindborg

how many calibration points are needed?

Could just take a brand new sensor and chuck it in a pan of water with a thermometer and simply take the resistance reading (or voltage) as the temps increase.

Should give a good enough calibration curve/line to suit. Could even lob it in the oven for over 100degs 🙂

rik1083

I found the sensor specs somewhere since I'm using orig sensor on dta
The thing I'm unsure about is alanoo's description of the pwm for stack.
From what he described it's like a 0.1hz frequency at something silly like 0.002% duty cycle

slindborg

I'll try to lob a scope on the line at somepoint

alanoo

rik1083 said:
I found the sensor specs somewhere since I'm using orig sensor on dta
The thing I'm unsure about is alanoo's description of the pwm for stack.
From what he described it's like a 0.1hz frequency at something silly like 0.002% duty cycle

Hey, this was not me, I have no idea at all at what they look like :wtf:

vocky

the stack dash does require a pwm signal for the temp gauge :thumbdown:

rik1083

oh those were rabidh's readings
is he still around?

I made a start on it last night, using some old pcb's I had from when working on cctv in a past job that have the basic layout I need to get going
I was thinking this will need a temp sensor of it's own (i.e. can't piggy back of the same one the ecu's using?)
I'm by no means an electronics expert, I'm much more a programmer and just learned what I needed do with electronic circuits to allow me to program the chips 🙂

alanoo

Yep would need another sensor (or maybe possible to use with the same as the ECU with a pullup resistor but as we all do not use the same, not sure it is smart...)

I think best would be to use the OE sensor, as we should all have it in a bin as standalones work with their "own" supplied sensor notsure.gif

rik1083

I will proceed using our oem sensor - I've got one plugging the extra hole on the saab head already 🙂 - but most ecu's will let u use any sensor as long as you know the resistance values etc..
but i should be able to make it programmable as pic's have eeprom and v easy to add rs232 interface to it

received code from rabidh that will help a lot thumbup

alanoo

rik1083 said:
I will proceed using our oem sensor - I've got one plugging the extra hole on the saab head already 🙂 - but most ecu's will let u use any sensor as long as you know the resistance values etc..

Yeah, tell that to the Webcon ECU guys that cannot do anything without going to a dealer 😃

alanoo

I'm just thinking of it now, but the Elise S2 uses a similar setup and all the Honda swapped ones have the same lack of temperature display on the Stack, guess there may be much more people interested notsure.gif

rik1083

anyone got the specs of the sensor? resistance vs temperature etc..
i think i tracked the sensor to bosch 0281002169 but not sure

alanoo

A french guy just gave me some Tech2 reading of the OE sensors

70°-2.8v
80°-2.4v
90°-2.00v
100°1.64v

approx 0.04v per degree

rik1083

alanoo said:
A french guy just gave me some Tech2 reading of the OE sensors

70°-2.8v
80°-2.4v
90°-2.00v
100°1.64v

approx 0.04v per degree

voltages are kinda useless like that 🙁
need resistances

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