[Start] [[Trigger] [[FuelInjection] [[Display] [[Wiring]]



We are now using the ground signal from one of the fuel injectors.

Using the ground signal of a stock ECU controlled fuel injector

The ground signal for the #1 injector is used as the trigger in the [MC Xpress turbo kits], so we are using this approach as well.

Overall it works out quite well!

We have done these input trigger circuit enhancements:

Note: There can be mistriggering sometimes when full throttle is applied, the stock ECU adds a lot of acceleration enrichment which creates this problem. But it is not an issue, one just has to be aware of it while tuning.

Using the rpm gauge output from the stock ECU

With a DVM the output was measured to have 13.4 VAC and 6.6 VDC towards ground. The signal strength is very low, so very high resistance is needed on the trigger input so not to disrupt the signal to the rpm gauge. It turns out that we better remove the R30 10KOhm pull-up towards +5V to get a good reading.

Using the stock crank trigger

Note: This method has been ruled out due to uncertainty about conflict with the stock ECU

Currently tested is the crank trigger, it is a VR sensor and is used with the LM1815.

Test 1 : 10 uF in series with trigger wire = weak at low rpm, functions well at higher rpm but stock ECU cuts out.

Test 2 : Added 220uF in parallel to the 10uF from first test. Same scenario, even weaker low rpm and stock ECU cuts out.

Measurements show 1.5 Volt AC and 3 Volt DC at idle. (between signal ground and trigger input). This is obviously a problem, I don't know why the bias voltage is as high as 3 V.

The stock ECU only cuts out when load is put on the engine at which point ground currents probably increase and cause interference. While free-revving the engine with no load there is no cut out, but as soon as full throttle pulls are made the ignition is cut.

Using the ignition coil primary ?

Note: This method has been ruled out due to high voltage

The voltage at igncoil primary is a bit high (also, dangerous to your health and your equipment).