oinojo Posted June 30, 2007 Share Posted June 30, 2007 hey guys, ive been having this problem. My car idles perfectly, however... when i give it throttle there is a knocking sound. At first i thought it was my valve lash so i adjusted it. Now that its adjusted im still getting the same sound. I know what bent valves sound like at idle but cant explain why it is doing this only on throttle. Any help/advice would help. Thanks Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted June 30, 2007 Administrators Share Posted June 30, 2007 As for your problem, could be a number of things. Here are just some examples… Pinging/detonation. To verify, first off unplug your vacuum advance from the distributor and plug the vacuum line going the throttle valve, and retest. If it still makes that noise, then with a timing light, back off ignition timing approx 5 degrees, (retard the timing 5 degrees from where it is currently at), and retest with the vacuum advance still disconnected. If it is burning lots of oil, that will cause the detonation as well. Fix the internal oil consumption issue. It could also be the timing chain slapping against the chain guides and front cover. That is usually a result of insufficient oil pressure to the chain tensioner and/or chain tensioner rubbing block and/or guides are destroyed/missing. It could be a rod bearing with excess clearance, i.e spun bearing. Or a collapsed/busted piston skirt allowing piston slap. Depending on the severity and amount of load being applied, either of these will be quiet at low load such as idle, but will knock/rattle as throttle is applied. If under wide open throttle, if it sounds as though someone is building a house under your hood, just turn off the key, open your check book and commence sobbing, unless you have a spare engine laying around. Your problem could be a number of other things as well. We really need more detailed information to help accurately diagnose without actually being there to see and hear this for ourselves. Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted June 30, 2007 Administrators Share Posted June 30, 2007 NARPS valves need cleaning. We do that here for a small fee. Quote Link to comment Share on other sites More sharing options...
oinojo Posted June 30, 2007 Author Share Posted June 30, 2007 As for your problem, could be a number of things. Here are just some examples… Pinging/detonation. To verify, first off unplug your vacuum advance from the distributor and plug the vacuum line going the throttle valve, and retest. If it still makes that noise, then with a timing light, back off ignition timing approx 5 degrees, (retard the timing 5 degrees from where it is currently at), and retest with the vacuum advance still disconnected. If it is burning lots of oil, that will cause the detonation as well. Fix the internal oil consumption issue. It could also be the timing chain slapping against the chain guides and front cover. That is usually a result of insufficient oil pressure to the chain tensioner and/or chain tensioner rubbing block and/or guides are destroyed/missing. It could be a rod bearing with excess clearance, i.e spun bearing. Or a collapsed/busted piston skirt allowing piston slap. Depending on the severity and amount of load being applied, either of these will be quiet at low load such as idle, but will knock/rattle as throttle is applied. If under wide open throttle, if it sounds as though someone is building a house under your hood, just turn off the key, open your check book and commence sobbing, unless you have a spare engine laying around. Your problem could be a number of other things as well. We really need more detailed information to help accurately diagnose without actually being there to see and hear this for ourselves. thats exactly what is happening. At low load there is little to no noise and the car idles fine. But when theres load it basically sucks... whats weird is that it comes and goes, but as of now 70% of the time it does this anywhere over 2k rpms:sad: Quote Link to comment Share on other sites More sharing options...
e_racer1999 Posted June 30, 2007 Share Posted June 30, 2007 man, that sucks! that's on your new turbo block? if you do need a new bottom end, gimme a call. i have an N42 block with dished pistons i'll get ya for cheap. or maybe swap for that tranny... Quote Link to comment Share on other sites More sharing options...
stagefumer11 Posted July 1, 2007 Share Posted July 1, 2007 take one plug lead off at a time, and find which cylinder is producing it. The noise will stop when you kill the spark. = no power Quote Link to comment Share on other sites More sharing options...
TimZ Posted July 4, 2007 Share Posted July 4, 2007 Could also be a leaking exhaust manifold gasket - this can sound a lot like valve clatter, and could come and go with engine load. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.