Scope waveforms

[andyfanshawe]

Hi Guys.
I would like to start a thread of good mark 8 scope waveforms.
They are a superb, unbeatable diagnostic tool as long as you can find somebody to do it!!

If anyone and everyone could add to these it would be good.

Anyway, heres a waveform of one of my primary ignition coils

The next 6 are nearly identical apart from this one that just happens to be an aftermarket one that was fitted just before i bought it.

Notice the first peak is lower than the second. No problems though.

Bear in mind the first peak must start with a ramp with oscillations at the bottom. There must be no vertical lines at all on the ramp otherwise the coil is shorted. The second and third peaks should be vertical. 6 to 8 amps total current for each one.

Consequently, as you can see, the Mark 8 has a multiple spark discharge ignition system with 3 burn events per cylinder rather than just the one. After a certain rpm it reverts back to one spark. I've yet to determine that point.

Here's a waveform of one of the injectors (all the rest were the same)

Notice towards the top of the ramp there is a slight dip caused by the injector pintle moving. Also notice the roughly 1 amp primary current.

If anyone else has any other waveforms would they upload? If anyone has any requests for any, I will try to oblige.

Andy.

 

[Pieces of 8]

dude i wished i had your equipment , wow.

 

[NetKeym]

This brings me back to the day when we used scopes that weren't on your laptop!

We've come a long way, baby!

Nice info in this thread - thank you!

 

[andyfanshawe]

Here we have a waveform at the battery with engine at idle

Heres the voltage waveform at the IAC (idle air control valve) with engine at idle and no electrical load

Here it is with AC and lights on

Since this is a pull down circuit, the low bit on the steeped waveform is the on time. No load is 31% on and AC and lights on was 34% on. So more air entering to compensate for the load.

Andy.

 

[andyfanshawe]

Setting up the pico for a TPS voltage check.

So, here's the voltage at the signal wire to the PCM from the TPS.

I made 2 full throttle openings from under the hood by hand (which is why the ramps are not smooth) and held them there for a second or so, then let it go.

Notice voltage ranges from about 1v to 4.7v.

We are looking for any spikes/dropouts in the signal. Luckily this looks okay.
Although I'm not convinced about the noise on the line at 0V.

I'll check the earths tomorrow for corrosion-just in case.

Andy.

 

[andyfanshawe]

Had a PO340 code today! Camshaft position sensor circuit failure.
Cleared the code and unplugged the sensor and plugged it back in. Not reoccured and drives well.
Decided to scope it to have a look at the signal.

Blue line is the signal line and the just visible red line is the signal ground. Both go back to PCM.

AC wave ranging from 3 volts to -3 volts. Not sure if that amplitude is okay but all seems well now. Waveform is clean with no dropouts.
Hmmm! keep an eye on that.

Andy.

 

[vr4]

damn i want a laptop scope.


all we have is the 5 gas and scope on a giant cart.