Hesitation and knock
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From: Louisville, Ky
Hesitation and knock I installed my cam and longtubes about 1000 miles ago. The idle will dip and surge from 300 - 1500 for the first 15 seconds or so at start-up. I have LS1 Edit but I have not had it tuned yet. I am waiting to get my ported Throttle Body and install my LS6 intake first. I was told running the car without tuning wouldn't effect the car negatively at all but I have read on here that the a/f could be causing 'cylinder washdown.' My gas mileage has dropped from 17mpg to about 14mpg so I'm assuming I am running pretty rich. It could be because my cam has a larger exhaust duration and I have a very free flowing exhaust. I'm sure the intake and TB would lean it out a little.
Anyway, lately I can hear a very loud knock in the engine especially during start-up. There is also a slight hesitation ocassionally at low rpms when beginning to accelerate. I burned two quarts of oil in the last 2k miles so I added some 10w-40 to see if the thicker oil would kill some of the knock. It hasn't. Could my spark plugs be loaded with carbon or something because of the extra fuel? I am going to pull the plugs to check. What should I look for and what else could it be? The car will be tuned in the next 100 miles or so. Hopefuly it will correct the idle and a/f. Thanks.
Anyway, lately I can hear a very loud knock in the engine especially during start-up. There is also a slight hesitation ocassionally at low rpms when beginning to accelerate. I burned two quarts of oil in the last 2k miles so I added some 10w-40 to see if the thicker oil would kill some of the knock. It hasn't. Could my spark plugs be loaded with carbon or something because of the extra fuel? I am going to pull the plugs to check. What should I look for and what else could it be? The car will be tuned in the next 100 miles or so. Hopefuly it will correct the idle and a/f. Thanks.
Last edited by SStolen; Jun 5, 2004 at 12:32 PM.
You should start by checking the plugs to see how it is running. Next install a catch can on the pcv line to cut down on oil usage. If you have edit you can lower the main ve table from 400 800 1200rpm columns by multipying by 90%. Cylinder wash is a bad thing.
