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Folks,
I'm struggling to understand my no code random misfires on all cylinders.
I Made a post before
https://www.civicforums.com/forums/355-engine/386498-misfire-low-gas-mileage-2014-ex.html

Anyways, it's at about 235,000km and the issue persist. The fuel pressure is correct so there's no issue with the fuel pump.

I was probably thinking I should scope around intake manifold and intake valve. A service advisor at Honda said that with high mileage vehicles they do fuel injection and intake cleaning.

​​​​​​I thought these were port injectors so the valves should be kept relatively clean.

The maintenance on this vehicle gets performed religiously. I have even adjusted the intake and exhaust valves and they are within specs from my last adjustment.

Has anyone had to perform any intake manifold cleaning and intake valve cleaning on this car as a maintenance? Did you find it was necessary?

 
Rep Power: 126

Never done a clean but it may not hurt to check your compression. Depending on what your oil change intervals were, there could be some bypass as the engine continues to wear. 235k would be premature but not implausible.

 
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That's one thing I haven't done.
I'll do a compression test. Never done one but it seems easy enough.

My oil gets changed every 6000 km or so. The most stretched it out was 8000 km. I use the oil and filter from the dealership. The car doesn't burn oil excessively. I think maybe the most it burns is probably about 1/2 quart maybe less.

 
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I apologize if I missed it, but have you checked valve lash?

 
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Yep. Twice. The good news is that it doesn't tick as much.
I also checked and made sure that the timing was good and nothing skipped. All the marking lined up.

I noticed that the oil/air separator cover is leaking oil just a little bit. It's not major and not impacting oil levels. I don't know if it's enough to upset anything?

Someone suggested that I should clean the EGR port passages to the block. I have a flexible steel wire and I was going to stick it in and see if it helps.

My local Honda said that the gaskets for the intake manifold are on back order and they haven't really sold any because they haven't had to take the intake manifold out for any servicing.

I'm all open for suggestions.
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