Subaru Impreza intermittent misfire under load - Secondary ignition waveform analysis with Pico

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We have a Subaru Impreza in that is exhibiting an intermittent misfire only when the vehicle is hot and under load. No codes in the system and idles fine. Using a capacitive pick up, we look at secondary waveforms on all four cylinders and found cylinder 4 failing under load. We analyse the waveform and prove why.

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15 сен 2024

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Комментарии : 45

@akaitv6606 3 года назад

Excellent diagnostics mate , more top mechanics are needed like you .

@romanosautomotive 3 года назад

Thank you and thanks for watching!

@d.d4184 4 года назад

Well explained. We are all learning from each other. When I seen the burn line sloping up I thought I was looking at a lean misfire.

@romanosautomotive 4 года назад

Thanks D. D - At a quick glance, it could definitely be interpreted like that. I hope what I said made sense. I'm not too good at explaining

@d.d4184 4 года назад

@@romanosautomotive I have a slow brain had to look at it again. I suppose when we see an upward curve on the spark line we shouldn't just think it's a lean misfire more so it's a sign combustion isn't taking place and we need to find out why.

@romanosautomotive 4 года назад

Perfect!

@kirkabrahamson1148 4 года назад

very nicely done Rob. Nothing wrong with your teaching style at all.

@romanosautomotive 4 года назад

Thanks Kirk, much appreciated brother!

@catzwa 3 года назад

Love the ScannerDanner test 👌🏼 I have a dedicated coil tester, but you have to take it off the car; this way is much easier! Awesome video as usual!

@romanosautomotive 3 года назад

Thanks Gary. SD is the master!

@adamking6419 3 года назад

Liking your channel. Keep them coming

@romanosautomotive 3 года назад

Awesome Adam, thanks for the support!

@theGADGETSplaylist 4 года назад

the POWER of secondary waveforms! and you are a good teacher Rome:)

@romanosautomotive 4 года назад

Haha, if I can one day explain things the way you do so clearly, I will be a happy man! Thanks Denis!

@jonalowe 4 года назад

Excellent tutorial. I learned a lot about secondary waveforms, and what carbon tracking looks like on a scope. The explanation about running out of fuel to burn and it's effect on the waveform was totally new to me. Keep it up!

@romanosautomotive 4 года назад

Thank you Jon!

@Automotive_Solutions 4 года назад

The scope sees it all, great video. 👍

@romanosautomotive 4 года назад

Thanks my man!

@techautomotriz138 3 года назад

Good video 👍

@rajdindial6740 4 года назад

Great vid again Rome.....and yes i think your a great teacher....

@rajdindial6740 4 года назад

Those diagnosis are spot on man

@romanosautomotive 4 года назад

I appreciate that Raj, thank you!

@DJ-tn7vj 3 года назад

Hi Rob. Will look into carbon tracking more.great video

@OzSkunkworks 3 года назад

Good video .. but u went straight to the problem cylinder .. I have a miss on possibly one cylinder out of 6 .. no codes to tell me which one.. It is an off idle miss just as u accelerate .. no miss at idle .. no miss at cruise . No miss under power

@romanosautomotive 3 года назад

The secondary ignition waveforms led me to the misfiring cylinder. Are you able to see any secondary waveforms at idle and under brake torque? Although it doesn't misfire the same, you might see an abnormality in one of the cylinders which can help you narrow it down

@High_Tech_Mountain 4 года назад

Great video and explanation! Thank you sharing!

@romanosautomotive 4 года назад

Thank you Angel!

@richardostrowski6420 4 года назад

Good job and a great video, well done sir.

@romanosautomotive 4 года назад

Thank you kindly Richard!

@GerardBurkeBurkesGarage 4 года назад

Well done mate, great presentation 👏👌👍

@romanosautomotive 4 года назад

Thanks Gerard!

@DanWallis86 4 года назад

Great video. Interesting how high the KV was prior to getting the new plugs and then how low it was afterwards.

@romanosautomotive 4 года назад

Thanks Dan, much appreciated!

@ExiledSynz Год назад

So check spark plugs .

@patadegrillo007 3 месяца назад

How you say spark plug wire down under?

@romanosautomotive 3 месяца назад

Ignition lead 😁

@padraiggalvin2807 3 года назад

Cool video. What exactly are you doing for the brake torque and is it the same for a auto/manual car?

@romanosautomotive 3 года назад

Thanks Padraig, the brake torque in auto is just foot on the brake in drive, and load the engine with the accelerator

@padraiggalvin2807 3 года назад

@@romanosautomotive Oh i see very good. And how do I do this on a manual car?

@TrevAutoTech 4 года назад

Do you this would show up in a primary waveform?

@TrevAutoTech 4 года назад

great videos BTW!!!

@romanosautomotive 4 года назад

Absolutely Trevor. If this was on a system where you could access the primary waveform, it would looks the same. There is no possible fault in the secondary that won't be replicated in the primary and vice versa.