beansbaxter
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- Nov 16, 2007
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I have a 2002 Accord SE Coupe. It's got the F23A4 motor with 165k miles and I'm having some problems with performance. At low RPMs, there is low but adequate power. It doesn't jump off the line but it's (barely) drivable. Once I get past 2500 RPM or so, the power seems to taper off and up past 4000 RPM and there doesn't seem to be any power left.
Put differently, it's easy to gradually come up to freeway speeds but there's absolutely no passing power. The symptoms don't seem to change when the engine is cold or warm.
Here's what I know so far:
Here's what I've done in the recent past:
I'm going to replace the exhaust manifold because of the leak but since it's up near the cylinder and not after the O2 sensor, I'm wondering if that could cause the P0420 code.
I'm also wondering if the loss of power can be attributed to the exhaust leak.
I have an Actron CP9180 scanner that can record data. I recorded a dataset while driving home the other day that you can download as an Excel file. I can record more if that helps the troubleshooting. I did notice that the second O2 sensor seems to fluctuate a lot more that it should, which is expected with this trouble code. If there's any other OBD-II data that would help with troubleshooting, please let me know.
Put differently, it's easy to gradually come up to freeway speeds but there's absolutely no passing power. The symptoms don't seem to change when the engine is cold or warm.
Here's what I know so far:
- OBD-II code P0420 is set and keeps coming back after clearing the codes
- The loss of power didn't immediately follow the P0420 code. It didn't really start losing power until at least 500 miles after the code first showed up.
- I found a small leak on the exhaust manifold. It's by the #3 cylinder up near where the tube is welded to the mounting plate.
Here's what I've done in the recent past:
- Replaced distributor cap and rotor
- Replaced spark plugs
- Verified spark plug wire resistances within spec
- Adjusted valve clearances. All valves were between .003 and .005 too tight.
I'm going to replace the exhaust manifold because of the leak but since it's up near the cylinder and not after the O2 sensor, I'm wondering if that could cause the P0420 code.
I'm also wondering if the loss of power can be attributed to the exhaust leak.
I have an Actron CP9180 scanner that can record data. I recorded a dataset while driving home the other day that you can download as an Excel file. I can record more if that helps the troubleshooting. I did notice that the second O2 sensor seems to fluctuate a lot more that it should, which is expected with this trouble code. If there's any other OBD-II data that would help with troubleshooting, please let me know.
