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#1
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Bad EGR Valve?
Hello,
My car 2000 Honda Prelude, 84k miles Recently, it pumped out black smoke under full throttle, but the black smoke disappeared after I replaced all the spark plugs. I'm facing a different problem now. At around 1500 RPM, the engine sorta knocks. It sounded like twirling a plastic bottle with a few marbles in it. Is this the sound of engine knock? Anyway, If I keep the engine at around 1500 RPM at neutral, then surely, there would be this noise. And if I race the engine and then let it fall back down to idle, right before it's to hit 1500 RPM, there is this noise. I do not hear this noise at idle or at higher RPMs. Does this sound like a bad EGR Valve? Or bad valve lifters or rocker arms? How would one go about troubleshooting this problem? TIA Andy |
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#2
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Is the check engine light on? Does the noise coming from the top end
or the bottom end of the engine? GET a screwdriver or mechanics stethescope to isolate where the problem may be. It could be a noisy valve train. It sounds like you don't have a engine bearing problem, or anything that has to do with the bottom end. Because a bearing knock will rise in noise level as the engine has a load on it and gets loader as a more of a load is put on. There a diagnosis you can do if it was maybe be a cracked flexplate. Raise the engine speed to high idle (1500-2000 RPM), then turn the ignition switch off. Before the engine stops, turn the ignition back on. If a knocking sound is heard when the engine restarts, the flex plate is cracked. To test a EGR valve you will need a vacuum pump with gaugue. To do this would be a lot to type. Also its possible that the black smoke is coming from a defective EGR valve but you replace the spark plugs to temporarily get rid of the smoke. What was the condition of the plugs? Did they have some carbon built up on them? You can aslo do a vacuum gauge test to verify a engine problem associated with this issue by unhooking the brake booster hose and put a gauge on it while at idle. Different readings mean differnent things. With so many sensors it is really hard to determine what the root problem is. |
#3
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Not familiar with model but on my car gently push up on the EGR diaphragm (underside of valve) and feel if it moves smoothly. Also can feel diaphragm with finger tip to see if moving when throttle opened. If not it could be dirty and sticking. If you gently push up on diaphragm when engine idling, engine will stumble. Not difficult to remove and clean EGR valve. I wrote a description of cleaning mine for my website (see below) under "Cars". -- ------------------------------------------------------------------------------ William R Watt National Capital FreeNet Ottawa's free community network homepage: www.ncf.ca/~ag384/top.htm warning: non-FreeNet email must have "notspam" in subject or it's returned |
#4
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"Garry" > wrote in message oups.com... > Is the check engine light on? No, the engine light is *not* on. As a matter of fact, I removed the EGR Valve positon sensor output from the valve and reved the engin in neutral and the engine light still would not turn on. I'm thinking the ECU might not even operate the valve in neutral. > Does the noise coming from the top end > or the bottom end of the engine? GET a screwdriver or mechanics > stethescope to isolate where the problem may be. It could be a noisy > valve train. It sounds like you don't have a engine bearing problem, or > anything that has to do with the bottom end. Because a bearing knock > will rise in noise level as the engine has a load on it and gets loader > as a more of a load is put on. The noise seems to be more clear on the driver side on top of the timing belt-water pump area with a stethescope. Come to think of it, the noise seemed to have started after I took the car in for a radiator flush at around 50K. The dealer did a back-flush, but I seem to remember from some Honda tech manual that you're not suppose to back-flush the radiator. Could the knocking come from the water pump? But only at around 1500RPM? > smoke. What was the condition of the plugs? Did they have some carbon > built up on them? The plugs looked perfectly normal with no sign of detonation, pre-ignition, nor carbon build-up. I guess that means I do not have a engine knocking problems then right? Andy |
#5
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I only vaguely recall the valvetrain setup, but you do have a VTEC
engine... there could be a valvetrain problem with the VTEC lifter components which only makes noise as the ECM is adjusting valve lift with the oil pressure control solenoid. Perhaps the rocker shafts are worn where the VTEC rockers operate. If this were deemed by an experienced ear to be likely, a simple removal of the valve cover would reveal the shafts and rockers for some rudimentary inspection. For that matter, the regular rockers could be worn also. It is hard to diagnose from a static, written description. Toyota MDT in MO |
#6
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I don't know, I took it to a Honda Dealer and they seemed to think it is
the water pump, but all this diagnosis seemed a little fishy because I did asked about a timing belt and water pump change a few days prior to today's "diagnostic". They recommend changing the timing belt and water pump and a $350 valve maintainance and they said this might not even be the problem and that I might have a timing belt tensioner problem and worst yet, they said Honda Care would not cover all this because this is normal maintanance. I called Honda Care and they told me that if the engine is making noise, then they will cover it. It all seemed too fishy so I'm taking my problem to the dealer whom I broght the car from. But anyway, doesn't the VTEC kicks in at around 5600 RPM? Would a bad valve train 'cause persistance noise at a small range of constant engine RPM? Andy "Comboverfish" > wrote in message ps.com... >I only vaguely recall the valvetrain setup, but you do have a VTEC > engine... there could be a valvetrain problem with the VTEC lifter > components which only makes noise as the ECM is adjusting valve lift > with the oil pressure control solenoid. Perhaps the rocker shafts are > worn where the VTEC rockers operate. If this were deemed by an > experienced ear to be likely, a simple removal of the valve cover would > reveal the shafts and rockers for some rudimentary inspection. For > that matter, the regular rockers could be worn also. It is hard to > diagnose from a static, written description. > > Toyota MDT in MO > |
#7
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Andy Chang wrote: > I called Honda Care and they told me that if the engine is making noise, then > they will cover it. It all seemed too fishy so I'm taking my problem to the > dealer whom I broght the car from. That sounds like a good plan. Your extended warrantee should cover abnormal engine noise regardless of cause, unless a normal maintenance item (timing belt) was neglected. I think the Honda recognized interval for that belt is 90k. Internal components should be covered unless it can be proven that fluid maintenance has been neglected. > But anyway, doesn't the VTEC kicks in at around 5600 RPM? Would a bad > valve train 'cause persistance noise at a small range of constant engine > RPM? I am used to what I see these days, which is Toyota's VVT-i system. It works in a significantly different manner (with the exception of their VVT-iL engine that uses high lift rockers like your Honda), but Toyotas will make a subtle rattling sound at a given held RPM. If there is a problem with the cam controller then they can get loud enough to signal a real problem. I would agree in theory that your Prelude VTEC system really only kicks in at high RPMs since is a valve lift adjustment, but my knowledge of Honda's system is very slight. Toyota MDT in MO |
#8
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On Sat, 8 Jul 2005, Comboverfish wrote: > That sounds like a good plan. Your extended warrantee should cover Warrantee: The party to whom the warrantor makes a promise. In this case, a vehicle owner. Warranty: The promise made by the warrantor to the warrantee. |
#9
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Daniel J. Stern wrote: > On Sat, 8 Jul 2005, Comboverfish wrote: > > > That sounds like a good plan. Your extended warrantee should cover > > Warrantee: The party to whom the warrantor makes a promise. In this case, > a vehicle owner. > > Warranty: The promise made by the warrantor to the warrantee. Right. I had "guarantee / guaranty" on the brain, which have for all purposes the same definition (not that many people use the latter spelling). I forgot that "warrantee / warranty" are not synonymous. As a fellow grammer cop, I thank you! Toyota MDT in MO |
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