I own a 2003 Matrix with the 1ZZ-FE engine and automatic transmission. I bought the vehicle with 182,000 miles and it now has 188,000 miles.
It has always had a bit of rattly noise. Specifically: it only starts to happen around 2000 RPM or higher, and it only happens with about 5% throttle. If the throttle is closed, no noise; and if the throttle is advanced past about 15%, no noise. During normal driving, you almost never notice it (except when it's a cold morning, in which case the noise is louder and more obvious the first 5 or so minutes) however you CAN reproduce the sound at will (even when the motor is fully at operating temp) by manually selecting a gear (i.e. putting shifter in 1st or 2nd) and driving around 2000-3000 RPM with a very light ~ 5% throttle application. You can control the loudness of the sound very well with the throttle position - silent at 0% throttle, progressively louder to about 5% throttle, and then gone again by 15% throttle. Vary the throttle position in that range, and the loudness of the sound varies in direct proportion. It sounds somewhat like a rod knock, although perhaps not quite as deep; and somewhat like a valve with too much lash - but not quite so "tappy".
When I bought the car, I did all the typical maintenance (thermostat, plugs, trans flush & new filter, PCV, air filter, replaced the PCV hose (it was cracked), and replace the intake manifold gasket (still had the old black one, not the second version orange one). None of that had any effect on the noise.
I have also done all of the following, all with NO effect:
I've stethoscoped numerous points on the engine. I THINK the sound is the loudest on the top half of the motor on the timing chain side, but it is very difficult (nearly impossible actually) with the car on ramps and not being driven. I may not be hearing the sound at all, or it's possible I'm hearing a very faint version of the sound (i.e. one that can only be heard with the stethoscope on).
I'm aware that the VVT-I controller/intake cam gear can cause issues, but my understanding is that unplugging the OCV (so the controller stays locked) should immediately eliminate the noise if in fact the controller is at fault?
I don't think it's timing chain noise (it doesn't sound like that to me), but I have not inspected the chain for slack/looseness.
From what I've read online, it doesn't have the characteristics of a piston (wrist) pin noise, and I don't think it's piston slap - I've driven piston slappers before, and the heat usually builds very quickly in the piston to dull the noise within 60-90 seconds; but this motor takes several minutes (on a cold morning) for the sound to diminish to the "normal" level. Even when it's stone cold, if you advance the throttle past 20-30%, the noise goes completely away (I hate doing that to a cold motor, but did it to test).
I'm kind of at my diagnostic end with this motor. If I was deaf, I would think I was driving a brand new motor (it runs excellent!); it's just the darn nagging noise. It seems like my only option at this point is to throw a timing chain and VVT-I controller at it, and if that doesn't fix it, drive it till it blows.
Any ideas???
Oh, background info: I have the maintenance history for the last 80,000 miles on this car. The oil was changed every 7000-8000 miles, and the car is NOT much of an oil burner (about one quart every 5000 miles). They (previous owners) certainly ran longer between oil changes than I would, but there is NO sludge inside the motor and with all the rod bearings in such excellent condition, I don't think it has ever suffered a "run low/out of oil" condition like some 1ZZ-FE's of this vintage.
It has always had a bit of rattly noise. Specifically: it only starts to happen around 2000 RPM or higher, and it only happens with about 5% throttle. If the throttle is closed, no noise; and if the throttle is advanced past about 15%, no noise. During normal driving, you almost never notice it (except when it's a cold morning, in which case the noise is louder and more obvious the first 5 or so minutes) however you CAN reproduce the sound at will (even when the motor is fully at operating temp) by manually selecting a gear (i.e. putting shifter in 1st or 2nd) and driving around 2000-3000 RPM with a very light ~ 5% throttle application. You can control the loudness of the sound very well with the throttle position - silent at 0% throttle, progressively louder to about 5% throttle, and then gone again by 15% throttle. Vary the throttle position in that range, and the loudness of the sound varies in direct proportion. It sounds somewhat like a rod knock, although perhaps not quite as deep; and somewhat like a valve with too much lash - but not quite so "tappy".
When I bought the car, I did all the typical maintenance (thermostat, plugs, trans flush & new filter, PCV, air filter, replaced the PCV hose (it was cracked), and replace the intake manifold gasket (still had the old black one, not the second version orange one). None of that had any effect on the noise.
I have also done all of the following, all with NO effect:
- swapped on a new intake manifold, thinking that perhaps the plastic baffle inside was loose. No effect.
- checked the metal piece inside the oil filler hole, thinking it was bent into the cam, but it was fine.
- replaced the cam position sensor (directly under the oil filler hole) because it looked slightly bent. No effect.
- unplugged the OCV, but this had no effect on the noise whatsoever.
- powered the OCV valve, and after 2-3 seconds the motor stalled (I believe this is a "OCV GOOD" passing result)
- checked the OCV filter, it was clean and clear.
- tried some 91 octane fuel, no effect.
- replaced the belt tensioner and belt. No effect.
- I became convinced that I had rod knock, so I inspected all the rod bearings. The crank journals are PRISTINE (they look like brand new from the machine shop) and the rod bearings looked excellent. I plastigauged one journal and it measured perfect.
- While the pan was off, I turned the crank plane to horizontal (i.e. all pistons halfway up/down the bore) and then rocked the crank back and forth a few degrees. NO mechanical noise was heard.
I've stethoscoped numerous points on the engine. I THINK the sound is the loudest on the top half of the motor on the timing chain side, but it is very difficult (nearly impossible actually) with the car on ramps and not being driven. I may not be hearing the sound at all, or it's possible I'm hearing a very faint version of the sound (i.e. one that can only be heard with the stethoscope on).
I'm aware that the VVT-I controller/intake cam gear can cause issues, but my understanding is that unplugging the OCV (so the controller stays locked) should immediately eliminate the noise if in fact the controller is at fault?
I don't think it's timing chain noise (it doesn't sound like that to me), but I have not inspected the chain for slack/looseness.
From what I've read online, it doesn't have the characteristics of a piston (wrist) pin noise, and I don't think it's piston slap - I've driven piston slappers before, and the heat usually builds very quickly in the piston to dull the noise within 60-90 seconds; but this motor takes several minutes (on a cold morning) for the sound to diminish to the "normal" level. Even when it's stone cold, if you advance the throttle past 20-30%, the noise goes completely away (I hate doing that to a cold motor, but did it to test).
I'm kind of at my diagnostic end with this motor. If I was deaf, I would think I was driving a brand new motor (it runs excellent!); it's just the darn nagging noise. It seems like my only option at this point is to throw a timing chain and VVT-I controller at it, and if that doesn't fix it, drive it till it blows.
Any ideas???
Oh, background info: I have the maintenance history for the last 80,000 miles on this car. The oil was changed every 7000-8000 miles, and the car is NOT much of an oil burner (about one quart every 5000 miles). They (previous owners) certainly ran longer between oil changes than I would, but there is NO sludge inside the motor and with all the rod bearings in such excellent condition, I don't think it has ever suffered a "run low/out of oil" condition like some 1ZZ-FE's of this vintage.
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