Weird fuel injector wave form

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Weird fuel injector wave form

Postby hijakd » Sat Aug 23, 2014 9:50 am

Hey guys I got a problem vehicle in on fri afternoon,it's a Holden rodeo with a 2.6 Isuzu petrol engine in it,i had a really quick look at it and i found it drops fuel pressure on a snap throttle test and also has a very weak ignition,also I found this very strange injector waveform on all four injectors,any idea why these injectors look like this? Many thanx
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Re: Weird fuel injector wave form

Postby Robski » Sat Aug 23, 2014 1:44 pm

Is this a one channel scope ?

How about inj current & CMP/CKP on the others ?
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Re: Weird fuel injector wave form

Postby Alan » Sat Aug 23, 2014 4:27 pm

Hi,

Can you post the .psdata file. Have you enabled a filter on the waveform it looks too "smooth".

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Re: Weird fuel injector wave form

Postby hijakd » Sat Aug 23, 2014 10:02 pm

Hey rob you could be rite,I will drop into work and double check that filters are off,also both 90 and 1 degree crank sig is perfect,and yes all injectors look exactly the same,I haven't done a current ramp yet as I only got half an hour with the car
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Re: Weird fuel injector wave form

Postby LucaB » Sun Aug 24, 2014 11:58 am

Hi

Engine must be running?

Possible resistance to voltage supply injectors?
Monitors current injectors

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Re: Weird fuel injector wave form

Postby hijakd » Mon Aug 25, 2014 12:15 pm

Iv had a deep look into things and his is how theses injectors look,engine runs perfectly,I also scoped another newer 2.6 and looks the same too
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Re: Weird fuel injector wave form

Postby hibeam » Mon Aug 25, 2014 5:31 pm

Hi,
I have come across such injector waveform on various Toyota models like corolla (earlier models)all running fine. I think this kind of waveform is from ECU that controls two injectors at the same time ie:cylinder 2&3 and 1&4..I would suggest you confirm if ECU fires each injectors individually..
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Re: Weird fuel injector wave form

Postby Steve Smith » Thu Aug 28, 2014 11:18 am

Hello Shameel and thank you for your enquiry.

Sorry for my late reply as I have been away on holiday and today is a catch up day.

I am not sure whether we have an issue with your injector signal or not, given the input and induced voltages remain as expected along with good injector duration with no voltage drop.

Ideally I would like to see the current measurement which would help describe the activity after injector cut.
Can you send a psdata file with the attached waveform incorporating a current view on channel B?

I would be very intrigued to add in the ignition event at the same time, as you have mentioned a drop in fuel pressure and a weak spark which could all relate to supply voltage and grounding.

Do you have access to the wiring diagram as this may reveal more about the circuits that we are not aware of?

With all channels utilised looking at circuits carrying load we can possibly link other events to the odd induced voltage injection pattern

I hope this helps, take care……..Steve
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Re: Weird fuel injector wave form

Postby hijakd » Mon Oct 13, 2014 10:57 am

hi steve I did a current ramp of the injectors and cam crank aswell,after repairing the ignition issue I had with the ute,its running perfectly,so it had nothing to do with inj voltage,further more I had two of these utes in for service two weeks later and checked the inj voltage non both,they are all the same,so it seems normal but odd,live and learn I guess..
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