Diagnosing engine problems with an oscilloscope

volvoskim · Post by **volvoskim** » 19 Jul 2011, 15:38

After a lot of attempts at trying to pin down the engine running fault on my 1994 Volvo 850,I bought off eBay, on the advice of a friend in the electronics industry, an oscilloscope that nailed down the problem as a faulty camshaft position sensor.
Great device that took a bit of research to get to know how to use,but gives you the power to look at a particular sensor is doing in real time,or its voltage and frequency.
A suitable one off ebay where there are loads of them, is only £50 to £100 so they don't cost an arm and a leg, unlike throwing parts at the problem in the hope of fixing it.

The picture is of the waveform of my RPM sensor,that somebody suggest I replace.The scope revealed it is working properly,spot on voltage and frequency with the TDC notch nicely shown.So if somebody is currently scratching their head, or emptying their wallet trying to diagnose a running fault,get hold of one and give it a go

If anybody needs any advice about using one drop me a line

: rpm.jpg (64.4 KiB) Viewed 3889 times

Post by **boosted5cyl** » 19 Jul 2011, 17:25

Good to see someone using their head. Didn't realize these could be gotten so cheap!

volvoskim · Post by **volvoskim** » 19 Jul 2011, 18:54

You really have to put some effort into using one,but they will save you a fortune fixing running faults.Plus I now have a few friends cars to diagnose,making some money along the way.

Post by **matthew1** » 19 Jul 2011, 19:05

Volvoskim, I don't hand these out lightly.

Good work.

volvoskim · Post by **volvoskim** » 20 Jul 2011, 09:25

No problem Matthew always willing to help out fellow Volvo owners.If anybody wants any help or advice on using an oscilloscope for diagnostics let me know

Ian

Post by **div4scpro** » 26 Jul 2011, 19:14

can you give me some criteria for selecting an oscilliscope or the ebay link that you chose?
Andy

Post by **thecheat** » 26 Jul 2011, 20:47

div4scpro wrote:can you give me some criteria for selecting an oscilliscope or the ebay link that you chose?
Andy

same here, I'm very interested... especially since there are a lot of cool pocket scopes for cheap.

would be great to say... find out WHICH plug is misfiring instead of guessing.

Post by **Red-Arrow** » 27 Jul 2011, 01:00

Oscilloscopes cost thousands of pounds when I was growing up. Only Universities and Companies could afford them. How the world has changed.

Very resourceful man.

Post by **precopster** » 27 Jul 2011, 01:40

I'm a big fan of Dwayne from Realfixesrealfast.com on you tube, He is a very methodical operator. A shame he mostly works on Dodges, Fords, Chevys only. The same principles apply though, no matter what the car.

Here he uses a scope to tie down a faulty O2 sensor.

I bet there's many Volvos out there that could use a scope diagnosis, especially those with poor fuel mileage.

Post by **thecheat** » 27 Jul 2011, 11:21

Plus, say you need to compare a properly running car to another, you just scope both and compare over the internet if you want.

There is a pocket open source one on ebay for $70... sooo tempting to impulse buy!