The following resources have been obtained while installing VEMS on Toyota 4A-GE 16V & 20V engines.
After the previous work using pull-down resistors we moved onto the suggested 10k->12V pull-up resistors and the addition of a 220nF cap on top of C40.
Still not good, the latest trigger log shows some strange missing tooth issues:
Action to try next:
- Try to match the OEM pull-up of 0.6V with smaller value resitors.
- Try pull-down resistors as before, but with LM1815 pin5 jumpered to cause LM1815 to ignore any voltage below 200-450mV
- Use a seperate ground feed direct to the LM1815 chip.
Toyota 24+4 Trace:
Recorded with USB Instruments Stingray
- Testing on the bench with: Recorded trigger as a wav works okay, testing distributor driven by a motor works fine.
- Testing with the trigger in the car through the loom does not give an RPM reading.
- so the amplitude is too small, or the pullup too strong
- DC voltage measurement ?
- AC voltage measurement ?
- RPM ? Cranking ? or somehow running engine (with alien ECU) ?
Config & Tables
The Ne (24tooth) trigger is connected to Trig1, the G1 (4 tooth) trigger is connected to Trig2. The G- combined ground connects to the common grounds. Two 270Ohm resistors pull the signal down to ground.
Test with the Ne and G1 trigger inputs changed over Ge to primary trigger, Ne to secondary trigger - we were out of clues so we thought we'd try it...
Changing back to the correct trigger connections but removing the pull-down resistors.
A log from the bench test
The owner of the car has produced a spreadsheet to try and analyse the trigger logs:
Toyota 24+4 Distributor:
#10 is the injector signal - indicating 1 injection event every two ignition events.
Divider=02 means injection event every second ignition event. Good if you have 2 injectors hardwired in parallel. (or, even than, you can (at the cost of a few wasted cycles) do something like: h=00 02 00 01 .. .. .. ..