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Pinpointing an engine mechanical-fault within minutes
Posted to Technical Discussion Forum on 9/20/2014 49 Replies


Ok...I was presented yesterday with a 2013 HONDA CIVIC Si (2.4L). The vehicle was towed in due to a "stall/crank,no-start". We had a heck of a time getting it started but when we did, it would barely rev and missed terribly. Codes were cleared and none presented in the short time we had it running. I will note that during cranking the cadence exhibited sounds of at least one dead-hole.

Up until yesterday I have experimented heavily with pressure/vacuum testing to supplement after wards, what I have proven otherwise with more traditional-testing. I do this so that I may safely learn by starting with a conclusive answer and working backwards to make the correlations. Im pretty excited about this case-study because, as you will see, Ive proved to myself that I have indeed learned from "practice, practice, practice" and can rely on these advanced tests to yield me conclusive-info without the more invasive/traditional tests (no more "training-wheels").

I began my testing with a 2-trace scope capture of RELATIVE-COMPRESSION and a #1 IC-COMMAND. My waveform displayed a lack of compression on cyl #4 only. I then added the FLS to the mix and attached it to the brake-booster port in the Intake-manifold. [2013 Honda Civic Si, Engine/Propulsion Waveform]

[2013 Honda Civic Si, Engine/Propulsion Waveform]

If you refer to the captures, you can clearly see the problem. With these two captures alone (approx 10min of my invested time) and an overlay, I could conclusively tell not only that cylinder #4 was leaking but the intake valve wasn't sealing properly. More-Importantly, justified the need to tear the top of the engine apart for further inspection. (Take my word for it...the configuration of the engine requires removal of the cowl panel just to remove the COPs and Valve-Cover.) Upon removal, the evidence was clear (refer to the attached).

[2013 Honda Civic Si, Engine/Propulsion Photo]

#4 intake rocker-assembly has failed/fell apart. A "C-clip" that holds the assembly together became dislodged. This allowed the pivot pin to move longitudinally and jam itself against the cam-holder, holding one of the #4 intake valves off its seat ever so slightly. [2013 Honda Civic Si, Engine/Propulsion Photo] [2013 Honda Civic Si, Engine/Propulsion Photo]

With the Rocker-Bridge assembly and both camshafts removed from the cylinder head, confirmation of the #4 intake valve's integrity was confirmed. It sustained no damage. Replacement of the #4 intake rocker-assembly was the only new component fitted to the engine and upon assembly, roared to life and didn't miss a beat!

This was the perfect opportunity to prove that learning this form of testing can save you boatloads of time and pocket-fulls of money. Please let me know what you think of the captures above and feel free to be critical...Im always looking to improve my delivery. (sorry about the you can see, I still need some practice with my presentation..VBG )....GET BACK TO ME WHEN YOU CAN! THANKS FELLAS!


Brandon from Florida

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car Vehicle Data

2013 Honda Civic Si 2.4L

Engine2.4 L
Trans6-speed Standard