05 Mazda 3 2.3l cam/crank relation

Hey all, I'm trying to verify valve timing by doing a cam/crank relation. I pulled a known good waveform from IATN of a 2004 Mazda 3 2.3l. Compared to the one I the taken it looks to be off. Car has low compression in all cylinders with 3 of them being half of the 1st one. To me it looks like the coil is firing in the same spot as the known good but the cam and crank seem to be off. Please give your advice thanks. First pic is of known good from iatn.com, the next few pics are what I found on the car I'm working on. Yellow is ckp green is cmp and blue is an amp clamp on cyl 1 coil. It's a two wire coil, correct me if I'm wrong but amperage measurements don't matter which side of the circuit your on? Anyways is this enough to warrant pulling the motor down. Engine has a chain btw and motor is suppose to be good. We just installed it in the customers car Friday.

It looks off to me too. Is there anything to the amplitude changes on the crank sensor?

Correct, current is the same on both sides of the circuit.

This was a used motor just installed that is running like this? Supposedly known good?

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We just installed a customer supplied engine that was suppose to be good. It has yet to fire off, I didnt want to waste more time pulling the front cover unless needed, this motor has a chain so im kinda worried as to how it got out. And yes this will be the last motor or trans i install that i dont provide lol to many headaches

Definitely off. With very rough measurements and gorilla math, it looks like the cam is about 60 degrees advanced of the crank. Not that it really matters. :silly: As long as the VVT solenoid isn't stuck open, you're pulling the timing cover off. OR, getting another engine to install.

...this motor has a chain so im kinda worried as to how it got out

It's a chain setup, but there are no keyways for the chain components. The harmonic balancer/CKP wheel, the crank chain sprocket, the exhaust sprocket and intake phaser, nothing. Friction and bolt tension are the only things that keep this thing in time. The bolts are TTY and one time use.

If the harmonic balancer was ever removed (for engine removal or installation), or the harmonic balancer bolt was loosened, then the engine very likely went out of time. You'll need the correct timing tool kit to get it back in time.

Timing is definitely off. I agree with Tyler that it's about the right amount and direction that it could be due to VVT.

Thrashnasty13 wrote: Car has low compression in all cylinders with 3 of them being half of the 1st one.]

I don't like this at all. 60* advanced would have the intake valves closing right around BDC, which should give high compression if anything. And one cylinder being double the other three is a big red flag. Personally I'd do a leak down test before tearing into anything.

Update here we did swap the harmonic balancer. So this could be our issue, ive never messed with this setup, is it possible it came out of time on cranking after swapping balancer? Such as we didn't get it torqued enough to keep in time?

Thrashnasty13 wrote: Update here we did swap the harmonic balancer. So this could be our issue, ive never messed with this setup, is it possible it came out of time on cranking after swapping balancer? Such as we didn't get it torqued enough to keep in time?

IMO, the damage was done the moment the crank balancer bolt was loosened. The crankshaft chain sprocket is then able to freewheel on the crankshaft.

It could have also happened during the initial crank? I don't know that it really matters now. You'll need to at least get the valve cover removed and the right CV axle out to get the timing tools installed to verify the timing problem.

Tutti57 wrote: It looks off to me too. Is there anything to the amplitude changes on the crank sensor?

Correct, current is the same on both sides of the circuit.

This was a used motor just installed that is running like this? Supposedly known good?

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I believe the change in the amplitude is an effect of the misfire. VRS sensors produce increased amplitude with increased rpm and lower amplitude with lower rpm. It’s actually pretty cool to see the cylinders not contributing (or contributing less) when scoping the VRS as opposed to a Hall effect type.

Why the right cv axle?

John Curtis wrote: [I believe the change in the amplitude is an effect of the misfire. VRS sensors produce increased amplitude with increased rpm and lower amplitude with lower rpm. It’s actually pretty cool to see the cylinders not contributing (or contributing less) when scoping the VRS as opposed to a Hall effect type.

The OPs captures are cranking not running. Seeing the amplitude/RPM change is cool though. it looks different after #1 TDC compression which is probably due to that cylinders higher compression maintaining engine speed.