stevevp wrote:I don't have a CIS-E system or DPR here at present so I'll be doing the CIS-E code last - volunteer test subjects most welcome
From the specs I can find the DPR is 19ohms, and probably driven PWM with some form of series load in the bosch ecu, as without it duty at load would have to be around 5% or less to get down to the specified current.
DPR 19 ohms pwm (at 100hz?) with an unconfirmed range of 0-140ma with normal operation between 10-35
roughly rounded, 19ohms at 12v gives 600ma and at 13.8 gives 720ma so starting duty to get 40ma would be 40/720=0.055556 or around 5.5% duty
an additional 160ohms in series should bring it to 33.5ma at 50% duty so the factory DPR operation range would need to be established to choose a suitable series load.
The reverse polarity only seems to be for fuel cut so I'm guessing the planned INJ2 output and the H-Bridge setup could be ignored completely if deceleration/rev-limit fuel management was not a priority
Kudos to someone for making this work! Understandably the MS moderators would be reluctant to support such a project because most people just throw away their CIS/CIS-E system in favor of EFI. And typically there isn't much performance gain to be had from adjusting fueling. But besides these legacy systems, there are some new applications which use a PWM or duty cycle control on a fuel metering valve. Throttle body injection or a metering valve are common on stationary gas engines with low pressure gas injection.
I did a lot of testing on the KE2.5 Jetronic 0 280 800 180. (KE2.5 is standalone fuel control on early Mk2 VW, such as 1.8L GTI 16V. KE3 is combined fuel and spark control on later Mk2 VW, such as 2.0L GTI 16V.)
- -50 to 150mA is confirmed with an 18ohm DPR valve. (Don't let it march up this far though, upwards of 100mA and the engine runs like crap.)
- HS and LS control on the valve. When HS voltage > LS voltage the valve opens. Difference across the DPR with resistance 18ohms equals drive current. In overrun fuel cut and fuel cut rev limit HS voltage < LS voltage and the valve is pinched closed at -50mA.
- Bi-level fixed current output when WOT switch is closed and running open loop. The output level appears to be hardware wired, though it is possible with chip tuning to alter the switching RPM point.
@stevep, why did you choose PWM control over duty cycle? For electronic controls to simulate an analog device isn't drive at a fixed frequency/PWM preferrable and then just vary the duty cycle to control the current?
For reference, here are similar circuit diagrams:
http://www.autolib.diakom.ru/CARS2/main ... t_ver1.pdf
Pins 4 and 5 are the DPR control.
http://www.autolib.diakom.ru/CARS2/main ... ke3jet.pdf
http://www.servotech.spb.ru/library/BOO ... _locon.pdf
Pins 4 and 5 are the DPR control.
