Volvo Problem Child.mp4

A Volvo 940 that had been through many shops trying to cure a misfire and pinging. Diagnosed quickly with a PicoScope, the WPS500 Pressure transducer and a little creativity. Brought to you by Autonerdz.

Category:

Autos & Vehicles

Tags:

• Volvo
• Misfire
• Pinging
• Pico
• Picoscope
• wps500
• autonerdz
• labscope
• training

[turbobuick33]

How did the original indexing of the flywheel get messed up?

[autonerdz]

@turbobuick33 Someone had instelled it incorrectly. While you can generally guess how a system might fail, you can never guess what someone might have done to a vehicle. That's just one reason why trouble charts don't work. :-p

[RUSS16V2]

Excellent video! GRUSS

[autonerdz]

@vgs8606 Most consumers of auto service don't know what they need to know to choose a good shop. Most pseudojounalism out there is just disinformation. Read this:

autonerdzdotcom/cancer.htm

[vgs8606]

@autonerdz This why I am always apprehensive about a timing job. A bad mechanic could install it with a teeth off and a worse mechanic will NOT own the problem. I had a Honda dealer mechanic screw timing so bad and until my wife hooked the timing light in their shop, they would not accept their fault! In this case it would have been obvious to the person who put new flexplate but still released the vehicle never the less.

[autonerdz]

@vgs8606 If you had an advance timing light with a scale that went that far, you may heve been able to guestimate that much advance. OBD-II? What OBD-II? This thing is way to primitive for even a basic data stream. :-p

[vgs8606]

@autonerdz Can you elaborate on it? Would a timing light be suitable to measure the 58 degree advance?  What about the OBD-II timing reading? Would it show 58 or 12?

[regnice01]

Amazing!!!!

[zx8401ztv]

My god, no wonder it ran rough.

Period measurement via an oscilliscope with 720 conversion, brilliant

and very accurate :-)

[autonerdz]

@1N4148 Nothing. It's just not as conclusive. The dampner could have slipped.

[1N4148]

So, you checked the timing. What's wrong with an ordinary timing light?

[spelunkerd]

Nice demo. You may not have even known that somebody had the flywheel off. I'm not surprised it went through several shops before the correct diagnosis was made. Too bad the problem couldn't have been adjusted electronically, without removing the flywheel again.

[maycor1076]

I have seen this also but I think the hardest problem to take is the next step. Your research and diagnostics procedures are great. There are many paths a take can take when diagnosing. For example using another software it would show that mechanically the vehicle is within time but out electronically. That only leaves cam and crank correlation. Seen it a lot with chryslers and a few like this cases. One of the easiest test is doing the amp probe test to see if flywheel is good. Good job

[autonerdz]

@lassebrann

The solution was re-indexing the flywheel as shown in the video.

[lassebrann]

How did you fix the problem? i have the same problem

[autonerdz]

@brettless80

Thanks for asking.

The current clamp is used during cranking to detect the peak currents from the starter as each cylinder comes up on compression.

[brettless80]

Hello,

Just a question? The current clamp used to detect compression (TDC) is it used only when cranking to detect this,or whilst car is running.

Cheers Brettless80

[nocturnando]

Excellent video I wish I could afford my pico right now, keep up the good work Tom and all the crew members.

[DrPicoflu]

Completely agree, thanks also to Rod for the compassion waveform viewer, great little tool.

[autonerdz]

@DrPicoflu

Thanks for watching.

Brian, our resident genius, did a great job with this one. What many consumers don't realize is that shops that can do diagnostics efficiently charge for the service and they will pay less for focused diagnostics at such a shop. The offerings of DIY diagnostics, or free diagnostics, often create more problems than solutions. Unfortunately, this myth is perpetuated by many uninformed 'consumer advocate' articles.

[DrPicoflu]

And it had been to so many shops, nice fix...

Doc...

[autonerdz]

@DrPicoflu

That would depend on the shop and the technician dealing with it. A shop with the diagnostic equipment and a skilled diagnostic tech to use them, should have been able to conclude that transmission removal was the next step in a couple of hours, including Alldata research. After that, the customer could have been presented with the prognosis and the estimate for trans R&R to pursue the problem and a retest to confirm repair.

[DrPicoflu]

Great case study Tom, out of interest, what would the chargeable diagnostic time have been for this diagnosis?