Injector wiring......
Discussion
Hedgehopper I've run some simple oscilloscope checks on the injector firing circuits today which may be of some help when troubleshooting for your injector wiring problems.
Equipment
- Windows 10 laptop
- Hantek 1008C PC 8CH USB Automotive Diagnostic Oscilloscope
- Multimeter
- RoverGauge (not essential).
Procedure
- Removed cover on ECU main connector.
- Pin input line 39 (white/black) ignition spark signal from coil.
- Pin output line 11 (yellow/white) injector bank firing pulse for even bank.
- Pin output line 13 (yellow/blue) injector bank firing pulse for odd bank.
- Connect 'scope Channel 1 to line 39, Channel 2 to line 11 and Channel 3 to line 13, all with good probe earths.
- Continuity check from 'scope pins to sockets on ECU connector to verify correctly connected.
- Run engine and adjust 'scope time base and voltage amplitude accordingly.
- Check for correct waveforms and capture for future reference.
Results
Display results should look similar to this example:
Where:
- Top white trace is the input ignition spark pulse wave form.
- Green trace is the even bank injector firing pulse waveform.
- Purple trace is the odd bank.
The results tie in nicely in terms of timing, a time base setting of 5 mS/div was set giving approx 16 mS spark pulse period, and approx 3 mS injector pulse width. RoverGauge display confirms this:
As does the theoretical timing diagram:
Conclusions
An injector firing pulse is fired for every other spark pulse, so four injector pulses are fired for one 4 stroke engine cycle.
At idle conditions, from the rising edge of the spark pulse and the resultant code interrupt, it takes just under 5 mS for the ECU to calculate width, set up the respective timer and issue the firing pulse.
I hope that helps.
Equipment
- Windows 10 laptop
- Hantek 1008C PC 8CH USB Automotive Diagnostic Oscilloscope
- Multimeter
- RoverGauge (not essential).
Procedure
- Removed cover on ECU main connector.
- Pin input line 39 (white/black) ignition spark signal from coil.
- Pin output line 11 (yellow/white) injector bank firing pulse for even bank.
- Pin output line 13 (yellow/blue) injector bank firing pulse for odd bank.
- Connect 'scope Channel 1 to line 39, Channel 2 to line 11 and Channel 3 to line 13, all with good probe earths.
- Continuity check from 'scope pins to sockets on ECU connector to verify correctly connected.
- Run engine and adjust 'scope time base and voltage amplitude accordingly.
- Check for correct waveforms and capture for future reference.
Results
Display results should look similar to this example:
Where:
- Top white trace is the input ignition spark pulse wave form.
- Green trace is the even bank injector firing pulse waveform.
- Purple trace is the odd bank.
The results tie in nicely in terms of timing, a time base setting of 5 mS/div was set giving approx 16 mS spark pulse period, and approx 3 mS injector pulse width. RoverGauge display confirms this:
As does the theoretical timing diagram:
Conclusions
An injector firing pulse is fired for every other spark pulse, so four injector pulses are fired for one 4 stroke engine cycle.
At idle conditions, from the rising edge of the spark pulse and the resultant code interrupt, it takes just under 5 mS for the ECU to calculate width, set up the respective timer and issue the firing pulse.
I hope that helps.
Edited by davep on Sunday 29th November 19:43
^^^^^^
davep, thanks for all of the above, it makes interesting reading but I have to admit seriously stretches my knowledge of electronics! I am slowly working my way through the wiring of the injectors but of course I may be wrong and the fault could be elsewhere.
Thanks to everyone else who has offered help and ideas...once it is sorted I will post the result in, hopefully, the not too distant future.
davep, thanks for all of the above, it makes interesting reading but I have to admit seriously stretches my knowledge of electronics! I am slowly working my way through the wiring of the injectors but of course I may be wrong and the fault could be elsewhere.
Thanks to everyone else who has offered help and ideas...once it is sorted I will post the result in, hopefully, the not too distant future.
davep said:
Conclusions
An injector firing pulse is fired for every other spark pulse, so four injector pulses are fired for one 4 stroke engine cycle.
DaveAn injector firing pulse is fired for every other spark pulse, so four injector pulses are fired for one 4 stroke engine cycle.
In your own words "Great set of results and well described procedure", its brilliant you've proved the theroy and we can finally put this debate to bed.
Four injector pulses are fired on alternating banks for one 4 stroke engine cycle, therefore each bank receives 2 pulses per valve opening.
I'll have to add to my Santa's list your "Hantek 1008C PC 8CH USB Automotive Diagnostic Oscilloscope" or Marks "Velleman PCS10/K8047 with PClab2000SE Data logger Software", that's a tough decision.
carsy said:
I always believed it to be this. And yes fuel gets injected onto a closed valve and just waits there until the valve opens. Its why when going to fully sequential injection you need bigger injectors to get the required amount of fuel in, in one go.
I've been following this thread for a bit of education and this statement raised a question for me. When injectors are discussed, the topic of spray patterns is aIso usually discussed and how it improves the fuel burn if you have better atomisation. If the fuel is just dumped into the inlet tract to wait for the valve to open then it seems that the spray pattern is unimportant. Have I missed something?
Nope, I`d say your bob on.
Thats why there is no gain between the originals and the Vectra`s for instance that people fit. The Vectras just flow more if looking for more fuel. I`ve spoke to Jools about this and he told me he has never noticed a difference between standard and Vectra injectors performance wise.
If going to fully sequential then yes the better spray pattern will be a big help as the injector will fire once at the correct time as the valve is opening.
Thats why there is no gain between the originals and the Vectra`s for instance that people fit. The Vectras just flow more if looking for more fuel. I`ve spoke to Jools about this and he told me he has never noticed a difference between standard and Vectra injectors performance wise.
If going to fully sequential then yes the better spray pattern will be a big help as the injector will fire once at the correct time as the valve is opening.
Edited by carsy on Monday 7th December 13:50
stevesprint said:
davep said:
Conclusions
An injector firing pulse is fired for every other spark pulse, so four injector pulses are fired for one 4 stroke engine cycle.
DaveAn injector firing pulse is fired for every other spark pulse, so four injector pulses are fired for one 4 stroke engine cycle.
In your own words "Great set of results and well described procedure", its brilliant you've proved the theroy and we can finally put this debate to bed.
Four injector pulses are fired on alternating banks for one 4 stroke engine cycle, therefore each bank receives 2 pulses per valve opening.
Colin RedGriff said:
carsy said:
I always believed it to be this. And yes fuel gets injected onto a closed valve and just waits there until the valve opens. Its why when going to fully sequential injection you need bigger injectors to get the required amount of fuel in, in one go.
I've been following this thread for a bit of education and this statement raised a question for me. When injectors are discussed, the topic of spray patterns is aIso usually discussed and how it improves the fuel burn if you have better atomisation. If the fuel is just dumped into the inlet tract to wait for the valve to open then it seems that the spray pattern is unimportant. Have I missed something?
carsy said:
Nope, I`d say your bob on.
Thats why there is no gain between the originals and the Vectra`s for instance that people fit. The Vectras just flow more if looking for more fuel. I`ve spoke to Jools about this and he told me he has never noticed a difference between standard and Vectra injectors performance wise.
If going to fully sequential then yes the better spray pattern will be a big help as the injector will fire once at the correct time as the valve is opening.
Great readThats why there is no gain between the originals and the Vectra`s for instance that people fit. The Vectras just flow more if looking for more fuel. I`ve spoke to Jools about this and he told me he has never noticed a difference between standard and Vectra injectors performance wise.
If going to fully sequential then yes the better spray pattern will be a big help as the injector will fire once at the correct time as the valve is opening.
Have never needed to know about the above but wanted to
A quick search pointed me to this topic
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