4.0L Scope Captures

I know not many of us have a scope but for those that do and/or are interested I grabbed Cam, Crank, Coil Control, Ignition Confirmation, and Injector control waveforms off my truck (2014 4.0L 65k mi).

I have the original scope files if anyone's interested I can DM or post them, SnapOn files can be viewed in the SnapOn data viewer and Pico files can be viewed in PicoScope 6 or 7.

11/29/22: Added vehicle speed signals.
4/26/23: Added A/C Lock Sensor Signal
4/8/24: Added ABS Sensor Signals
9/20/24: Added Cyl 1 Compression with Cam & Crank Signals

Both were taken at a hot idle.

Cam & Crank Signals



Crank, Coil, & Injector Signals


Cyl 1 Compression, Cam, & Crank @ hot idle.


Vehicle Speed Signal Input & Output (aprox 0-5-0 mph)


A/C Lock Sensor Signal


ABS Sensor Signal (Forward)


ABS Sensor Signal (Reverse)

 

Had a perfect example today of why you shouldn't replace parts based on a code, had an 08 FJ Cruiser 4.0L (Same engine as the Tacoma) come in today with P0340 (Cam Position Sensor A (bank 1) Circuit) and P0335 (Crankshaft Position Sensor Circuit) codes. Knowing Toyota cam and crank sensors rarely fail I first looked for any obvious wiring damage and found none, next I hooked my scope up to the Cam and Crank sensor signal wires at the PCM and got the capture below.
Notice the missing signals (The cam signals should each have 3 notches per rotation), no matter how many cam/crank sensors or PCMs you put in this thing you would not have fixed it.



Next I pulled the bank 1 cam sensor, used my bore-scope to look at the reluctor wheel and found it to be broken.

 

Good catch.

I rarely use the scope anymore, its a huge pain to set up (picoscope) I learned on a snapon 4 channel scope.

I miss the old days of dedicated units that turn on and go right away.

The best part of modern ones is that it can show you known good. But you had bank 2 sitting there haha.

 

I don't have a Pico, I'd kinda like to have one but boy they are proud of them.
That's why I like my Verus scope, it's right there all I gotta do is hook up the leads.
I also have a U-Scope from AESWave, It's perfect for those quick things that don't require a multichannel scope like ABS sensors or a simple control circuit.

 

Yea I know it's not for everyone but it really is a powerful tool if you know how to use it, I did that diagnosis above in under 30min.
Unfortunately even the majority of automotive shops don't have one much less know how to use one and instead rely on winging parts at problems until they fix it, the customer runs out of money, or they run out of parts to change.
I have diagnosed so many things with a scope already and I'm no expert at using one by any means.

 

Scopes are useful for many things aside from automotive stuff. Ever mess around with a raspberry pi or any other small circuit and want/need to verify a signal… there are other cheaper alternatives. I’ve use these quite a bit and they’re great units.

$628 Analog Discovery 2: 100MS/s USB Oscilloscope, Logic Analyzer and Variable Power Supply

https://www.amazon.com/Digilent-Dis...gid=pla-522977565083&ref=&adgrpid=70729707553

 

Well stated !!

Thanks for posting !!

 

Bread and butter! Keep up the good work.

 

I have a simple 2 channel oscilloscope ("scope") I use for electronics. Never thought about hooking it up to the truck... Is it as simple as hooking it up to the sensor?

 

Any speculation on how the reluctor broke? I have seen it happen, but it has been far and few between.

 

Providing it can handle the voltages yes it's the same concept, sensor signals are typically no more than battery voltage but if you get into injector and coil primary signals those can spike well over 100v.

If you watch the youtube channels in my signature there's alot of scope usage.

 

I'm guessing metal fatigue makes them crack and eventually fail but I couldn't say what the root cause is, it did have 200k miles on it but thats not really high mileage for a 4.0.
I have seen a few people on here that have had them fail in a similar fashion.

Maybe we should be checking them for cracks when we do valve cover gaskets.

 

I watched the 1st video, "Pulling codes and changing parts is not a diagnosis!" That is an awesome video!...I'll check out the rest.

 

It also makes me curious about the maintenance of the OCI. Need to compare to documented breakages that have been posted on here, or the 4Runner forums, to see what if any similarities there are.

 

It didn't look like it was maintained all that well but I mean the reluctor is a peice of stamped steel.
Maybe if the ports or valves for the phasers get plugged up and cause them to "hunt" it causes some kind of harmonic vibration that would fatigue and crack the plate.
I don't think we are getting the job so there probably won't be any further investigation into this one.

 

Well if they ran it low on oil, and the phasers were slamming, due to not being able to maintain, over a long enough period, that is a possibility I suppose. They rattle very loudly.

 

For sure low oil would cause phaser knock as well as timing chain slap.
Anyway we know they are prone to breaking and would definitely be something to check for anyone that gets cam/crank sensor codes.

 

Didnt they change the design of those reluctors at some point in the life of the 1gr single vvti?

 

The only one I know was different was the 03-04 4Runner 4.0, as far as I know all other single VVT 4.0L engines have the same Cam/Crank reluctor profile.