Poobah Posted November 28, 2004 Report Share Posted November 28, 2004 Sometimes, lately, when I do a WOT or hard acceleration I get some fairly severe detonation. Usually when I get on it, there isn't any detonation but it has been happening often enough lately to concern me - I know it isn't good for the engine. I'm not getting any codes. I've always used premium gas. I replaced the EGR valve, cleaned out the passages, mouse holes, phenolic spacers, etc. about 20,000 miles ago. The only other possibly related symptom is an occasional very slightly rough idle that is just barely noticable. I replaced the plugs and plug wires with O.E.M. about 15,000 miles ago. Any suggestions as to the cause of the detonation? Thanks. Happiness is owning a Cadillac with no codes. Link to comment Share on other sites More sharing options...
MAC Posted November 28, 2004 Report Share Posted November 28, 2004 It may be that your fuel pressure regulator is on the way out. Running too lean? Do you have detonation when you start-up? Link to comment Share on other sites More sharing options...
Poobah Posted November 28, 2004 Author Report Share Posted November 28, 2004 No detonation on start-up but I have noticed that the miles on a tank full of gas vs. the fuel used adds up to better milage than the average MPG per the computer lately. Could this be an indication of running too lean? Happiness is owning a Cadillac with no codes. Link to comment Share on other sites More sharing options...
Ranger Posted November 28, 2004 Report Share Posted November 28, 2004 Wouldn't a bad FPR cause a rich condition as a leaking diaphram would put unmetered fuel into the intake via the vacuum hose? Link to comment Share on other sites More sharing options...
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