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PIP5159A: Engine Misfire May Be Due To Spark Plug Wires

The below TSB describes missing or damaged " spark plug C" attachment clips as a source of engine misfires in 2014/15 Corvettes.

On the last couple of hundred miles of our road trip, while in 7th gear (7M trans), doing 72 MPH (about 1,500 PRM), flat level pavement, a couple of times when I stepped on the throttle to pass, I felt what might be an engine miss. Was not sure, and thought it might even be bumps from pavement irregularity. Accelerated at the expected moderate pace. However, when I downshifted to 5th, the car took off like a rocket. Also a couple of "possible misses," at similar RPM, in 6th gear.

What could be the cause? Thought of a coil problem (some C7's have had this), bad gasoline, spark plug wire loose, or ??? As Rich Willhoff, Service Manager of our supporting dealership Abel Chevrolet, also has a new Z06, and remember reading that Rich had volunteered his expertise to diagnose and fix a loose plug wire which caused similar motor hesitancy on another 2015 Z06 at a track, called him this morning. He agreed with all my possible causes, adding another one, for he too had experience the exact symptoms on his Z under the same interstate driving conditions. He added that it could be possible fluttering of the supercharger BOV (blow off valve) at low RPM. Thank you Rich for taking the time to talk with me!

I already had made an appointment with my Technician, for I wanted to be sure that driving my car was fine, OR, that something needing to be fixed. My Tech and I discussed all the above, and he went to work. Half hour later, he told me he had found that my # 3 cylinder had shown 4 misfires, and when he then went to cyclinder # 3, he immediately found that the spark plug wire too easily detached (not enough "C" clip tension). (He pulled the # 3's spark plug and showed it to me, saying it looked just about new.) He then replaced the # 3 cyclinder's spark plug wire with its integral "C" attaching clip.

He also checked the "attachment strength" of all remaining spark plug "C "clips, and determined all were exactly what he wanted/expected.

Here is the first page of the TSB (second page is one short paragraph, with no additonal relevant info).

Text Font Audio equipment Paper
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