Jaguar XJS Injector waveform

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Jaguar XJS Injector waveform

Postby sovereignxj81 » Fri Nov 02, 2012 12:36 am

Hello
I have recently purchased a 2 channel Picoscope, wanted one for ages anyway.

The car in question is a 1994 Jaguar XJS 6.0L V12. Using the scope on channel "A" with the break out lead supplied I have plugged into each injector plug in turn & also using the 60A current clamp on channel "B" to check the injector current, clampted onto one of the leads on the break out lead. I have been checking the waveforms on each injector. I dont fully understand the voltage patern yet, but the voltage waveform appears to be the same on each injector. My question is that the current waveform is different on each injector. Some current waveforms appear to be the same & some are different. Could I Please be advised as to what I should expect to see. I have had the settings on the scope both channels in Auto mode. In other words there are different erratic current waveforms on each injector. I have checked each injector with a DVM fluke & each injector resistance is 2.4 ohms correct. The injectors are new & I have had them ultrasonically cleaned. The injectors fitted to this vehicle are the current controlled type.

Further more to my query, what effect on engine fueling would too high or too low injector current be, above or below nornal reading.

The reason for this quest, is to establish why the Cats are smelling of rotten eggs, I beleive that I my have an overfuelling problem.

Thank you for any help that you may provide
Steve
sovereignxj81
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Re: Jaguar XJS Injector waveform

Postby Liteace » Sat Nov 03, 2012 11:09 am

Stick a gas analyzer up its bottom and have a look to see whats going on there, also save the waveforms you have and load to here so we can have a look to see whats going on
DONT SHOOT YOURSELF IN THE FOOT
Liteace
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Re: Jaguar XJS Injector waveform

Postby sovereignxj81 » Sat Nov 03, 2012 1:27 pm

Hi
I do not possess a exhaust gass analyser. The car is off the road, so I am unable to take it anywhere. How do I upload the wavefrorms & place them on this web site??

Thank you
Steve
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Re: Jaguar XJS Injector waveform

Postby Liteace » Sat Nov 03, 2012 4:58 pm

Save the waveform in File > save in the pico software then click on upload attchment here on the form, just under where you click on submit after repling
DONT SHOOT YOURSELF IN THE FOOT
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Re: Jaguar XJS Injector waveform

Postby sovereignxj81 » Sat Nov 03, 2012 7:35 pm

I have been having a read on the web & the problem that I seem to have is that the current waveform, is not as listed for peak & hold type injectors. My current trace is a low peak hashy one, varying from injector to injector. On the 1994 Jaguar XJS 6.0 the injector connector is a 6 way connector sited on the innner O/S front wing. I suspect that I may have a high resistance connection. I will be carrying a fully EFI wiring loom check, using the scope.

What I have presumed that if the injector is not receiving the correct ammount of current, due to faulty loom connectors, then the injector is not opening properly, therefore no administering enough fuel. This would cause a lean misfire. The EFI system would then increase the injector pulse width & place more fuel into the exhausts, unburnt fuel, which is causing the rotten egg smell, that I am experiencing.

Am I on the right tracks

Thank you
sovereignxj81
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Joined: Fri Nov 02, 2012 12:15 am


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