Cylinder misfire identification with WPS 500

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Cylinder misfire identification with WPS 500

Postby Henri Malcorps » Wed Aug 20, 2014 4:33 pm

I have a misfire on cylinder 3 of my MGTF and try to verify if it is due to the injector. For this reason I connected my WPS 500 at the vacuum inlet of the pressure regulator but I was unable to obtain a significant output signal. I was able to obtain valid signals from the exhaust and the vacuum, but not from the pressure regulator. This, although the regulator seems to work well; no black smoke, no starting problems. The car drives well_ except the mis fire from cylinder3. Ignition is ok, switched sparks and ignition coil and the misfire stayed at the same cylinder (verified with my scanner). What might go wrong with the measurement at the pressure regulator?
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Re: Cylinder misfire identification with WPS 500

Postby arjen » Wed Aug 20, 2014 7:37 pm

No idea what the problem is for the fuel pulse measuring, connected as short as possible?

Do you have good compression and have you carried out an leak test on cilinder 3.
Both coils consuming the same current?
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Re: Cylinder misfire identification with WPS 500

Postby Robski » Wed Aug 20, 2014 8:17 pm

verified with my scanner
did the exhaust pulses agree ?

For this reason I connected my WPS 500 at the vacuum inlet of the pressure regulator but I was unable to obtain a significant output signal.
what did you have it set to ?

I haven't tried with the WPS myself as i have a FLS.

What might go wrong with the measurement at the pressure regulator?
pilot error....maybe.....if not the WPS isn't up to the job ?
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Re: Cylinder misfire identification with WPS 500

Postby Henri Malcorps » Thu Aug 21, 2014 12:24 pm

Arian: access is difficult, connection is about 20 cm. It is a wasted spark ignition. Same coil for cylinder 3 and 2. I didn't do a leak down ore compression test, but MAP with my scanner was OK.
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Re: Cylinder misfire identification with WPS 500

Postby Henri Malcorps » Thu Aug 21, 2014 12:37 pm

Robsky: my scanner and exhaust pressure both indicate cylinder 3. I tried all possible settings of my wps. Maybe also the pressure regulator is stuck. I have no reference waveform except one on this Pico site.
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Re: Cylinder misfire identification with WPS 500

Postby Bubeh » Fri Oct 03, 2014 8:04 pm

Try to do an injector voltage test on injector three. I am thinking of a stuck open pintle in injector 3 (no hump at end of waveform). If so, try to tap injector with screw driver while re-scoping and if hump appears then it confirms a stuck pintle; cleaning or replacing is an option...
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Re: Cylinder misfire identification with WPS 500

Postby terbo » Sun Oct 12, 2014 4:21 pm

Can someone explain how to set up the Pico and WPS500 to
get a reading for Exhaust-Pressure at the Tailpipe to determine what Cylinder is misfireing ?

I am using the Menu-Settings given in the Pico-Software sofar...

I tried with many Cars, but i can´t get anything what i understand as far as
knowing witch Cylinder is the Problem.

How does a good one look, how a Bad one ?

That would be a very cool Funktion for Pico Diagnostics , if it could do this !!
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Re: Cylinder misfire identification with WPS 500

Postby Henri Malcorps » Wed Oct 15, 2014 5:46 am

Hello Terbo,
What kind of engines did you test? Interpretation of 4 cylinders is rather easy but I didn't really succeed in interpreting the exhaust signal of my Rover V8. I use a WPS 500 on the zoom function 2 with an Owon scoop.
I tried to put a powerpoint with a few slides in attachment, but don't know if it succeeded.
I also recommend you to do a Google search on "FirstLook User's Guide For Spark Plug Engines" http://senxtech.com/wp-content/uploads/ ... l_v3.3.pdf

Henri Malcorps
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Exhaust pressure variation at idle.pptx
(291.28 KiB) Downloaded 212 times
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Re: Cylinder misfire identification with WPS 500

Postby Steve Smith » Thu Oct 16, 2014 11:23 am

Thank you Terbo and Henri for the posts and presentation.

With reference to
Can someone explain how to set up the Pico and WPS500 to
get a reading for Exhaust-Pressure at the Tailpipe to determine what Cylinder is misfiring ?


Could you take a look at the thread below that does go into the complexities of this form of diagnosis which does have real value but certain limitations

https://www.picoauto.com/support/topic10159.html

Take care....Steve
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Re: Cylinder misfire identification with WPS 500

Postby terbo » Sat Oct 18, 2014 5:15 pm

Thanks alot, very good PowerPoint !
And very intressting link, thanks for that, i didn´t find that...
I will take a few samples and put them here when i get the chance.

Chris
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