Sale ends todayGet 30% off any course (excluding packages)

Ends in --- --- ---

low impedance injector oscilloscope wave

General Tuning Discussion

Forum Posts



Tech Articles

Discuss all things tuning in this section. News, products, problems and results. 

= Resolved threads



i do some test with oscilloscope low low impedance fuel injector peak and hold

do it with test output motec m800 setting was (4080 rpm-15ms-50%duty cycle)

so as i do search and not get the wave should be the injector with correct peak and hold

so i attach some pictue and helpfully give me advice how the wave should be reading


Attached Files

The waveform is interesting, but the bigger question is... why are you bothering with this? There are a lot of simple modern high impedence injectors that don't use peak and hold drivers.

The actual current delivered to the injector may depend on the injector's resistance when the ECU is doing that method of peak-hold operation. Most low-impedance injectors measure approximately 2.0 -3.0 ohms resistance, so if yours is similar then the current probably matches what the software settings claim. There are special current-measuring probes you can attach to your oscilloscope if you need to measure this. I've used one that looks similar to this: https://www.tequipment.net/AEMCSL206.html . I haven't used this one from Picotech, but their other products are good so it's probably worth a try: https://www.picotech.com/accessories/current-probes-clamps/60-a-current-probe-bnc

If you are using the custom-machined 'billet atomizer' style injectors with very high flow rates and very quick response times, be careful because it is possible to damage them by using too much current or too much duty cycle.

The waveforms looks like what I would expect to see. The ECU drives the injector till the current through it reaches 4 Amps, then starts pulse width modulating the signal to keep the current at a lower 1 Amp.

You really need to measure the current through the injector, not just voltage applied to it, as the two are not simply related by the resistance of the injector because its an inductive load. You can do this a cheap way by putting a 0.1Ohm 5Watt resistor in line with the injector and measuring the voltage across it. As this load is purely resistive, the current through it can be calculated using Ohms law, and because the resistor is in series with the injector, the same current passes through both.

We usually reply within 12hrs (often sooner)

Need Help?

Need help choosing a course?

Experiencing website difficulties?

Or need to contact us for any other reason?