Fouled plugs ? - ZR-1 Net Registry Forums

A26B · 10-05-2016

Dry soot vs Oily soot on plugs would indicate fuel or spark issue as opposed to oil fouling from guides or rings. 4 & 8 are not paired cylinders so it would require 2 coil or 2 plug wire issues.

No fuel pressure leak-down would indicate the injectors are not at fault mechanically.

Question: is the engine missing? Have you tried a low rpm (12~1500 rpm) pull in 6th gear? Does the engine buck or does it pull smoothly/gradually? Weak spark is usually the culprit if engine acts like it has modified camshafts.

Also of note: You mentioned the ECM being replaced. What is the background on the replacement ECM? Used, reconditioned, new, known to be good by test in another ZR-1?

10-05-2016	#11
A26B Join Date: Dec 2003 Location: Arcadia,OK Posts: 3,395	Re: Fouled plugs ? Dry soot vs Oily soot on plugs would indicate fuel or spark issue as opposed to oil fouling from guides or rings. 4 & 8 are not paired cylinders so it would require 2 coil or 2 plug wire issues. No fuel pressure leak-down would indicate the injectors are not at fault mechanically. Question: is the engine missing? Have you tried a low rpm (12~1500 rpm) pull in 6th gear? Does the engine buck or does it pull smoothly/gradually? Weak spark is usually the culprit if engine acts like it has modified camshafts. Also of note: You mentioned the ECM being replaced. What is the background on the replacement ECM? Used, reconditioned, new, known to be good by test in another ZR-1? __________________ Jerry Downey JERRYS LT5 GASKETS & PARTS http://www.jerrysgaskets.com 1994 *ZR-1*, Black/Black, Lingenfelter Aerobody, 416cu in, 3.91 gears, coil-over susp, Brembo brakes, etc. 2016 Black-Red, 3LT-Z51 Auto 8-speed.