Power Loss When Warm - Timing Issue?

Hi all,

I have a weird issue on my 2004 Mazda 3 2.3L (non-turbo, cable throttle), where letting go of the throttle causes the engine to shudder and drop RPM harshly, but ONLY when the engine has warmed up.

I have taken a screenshot of my timing advance while driving and the issue occurs, and this is what I have recorded:

My current suspicion is a faulty Crankshaft Position Sensor, which I will be replacing soon. I noticed it is covered in oil:

Any ideas what this issue may be?

Thank you!

Could be ignition related? Coils? Icm?

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RockAuto shows an electronic throttle body for your engine?


Thanks for the replies! It could be a coil. Would this show a CEL? I have no CEL which has really made things more difficult.

I also got confused with the throttle body situation. It’s definitely cable, and realised that only Australians got a cable throttle on the earlier models. So weird lol

I would doubt timing, throttle body I would look at first.

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If the engine has a cable operated throttle body, then the Idle Air Control valve may be the problem

This is what controls the engine idle speed whenever the accelerator is released.

It may just be dirty or defective.

Aussie huh?

How 'bout some shrimp and rice on the barbie?


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I’ve taken the IAC off and given it a good clean, but maybe it is defective… Is there a way to test if its working all good?

The thing that confuses me is the fact that the issue only occurs when the car has warmed up!

Haha and yes Aussie - which makes the warmed up thing a whole lot worse with our summers!


Try this.

When the engine is warm and idling, take the handle of a screwdriver and rap on the IAC valve.

If the engine idle speed changes or the engine stalls, the IAC valve is defective.


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Interesting - I will definitely try this next time I go for a drive.

I’ll keep you up to date. Thanks!

So… I tried the screw driver tip and it passed the test.

Now weird issue, I was cleaning the sensors with some contact cleaner, and I took the car for a test drive and the pre-cat O2 sensor seems to have died and pulled a P0132 code.

Ive checked and changed fuses, and nothing seems to have changed. I’ve tried clearing the code but it keeps coming back, so I’ve ordered a new O2 sensor.

I didnt think the contact cleaner was conductive, but it said on the bottle to not use it on an energised contact, which was probably my mistake. Doesn’t matter, it was an old O2 sensor anyway.

I guess my next update is when i replace the crank and o2 sensor haha