Hey guys.

Need some advice. I'm having all of the above mentioned issues with my 01 prelude. Most of what I'm noticing is at idle but if I accelerate easy I feel what seems like a misfire, or a dead spot in power especially between 2000 and 3000 rpms.

I've replaced the distributor rotor, which I found to be half burnt. Surprised it didn't fix the issue. Replaced the plug wires, put in vastly too costly denso double plat spark plugs.

I keep getting a p0420 code. I'm watching my o2 voltages and sure as crap my sensor 2 is mimicking sensor 1 voltage oscillation, but I cant discern if this is a bad cat or bad o2 sensor because while I do have that rough idle and some power issues, the car starts and goes down the road well enough. I keep reading that the cat being plugged would cause substantial performance issues, where as mine seem moderate at best. Am I wrong?

one thing I know for certain, I do have a pre cat exhaust leak right at the flange for the downpipe and the cat. Can that cause these issues? I'm here because I need some guidance as where to go. Both cats and o2 sensors are semi costly and PITA repairs considering I have to jack my car up on sand lol.

Feel free to ask any questions to help you help me. Thanks!

putting in a pic of my o2 sensor voltages, short term fuel and iat (why its 158 degrees is beyond me)

 

if nobody hasnt chaged cat and o2 ever it could be that theyre the problem - hard to tell but anyway you should repair that leak and magnalow cats are not THAT expensive

you should also do valve adjustment and clean IACV, EGR, FITV

 

Ah the parts I forgot. FITV is newly replaced. Valve adjustment has been done several times to get to what I feel is right. I had head work done when the engine was rebuild. My valves before were shredded. Tapered to almost a knife point. The machinist I took it to insisted it was salvageable and did an interference cut on the seats. 45 degrees I think he said. I'm honestly thinking he did a shoddy job and there are problems with the valves again. But the data from the scanner still shows cat/o2 issues so I've put that thought on the back burner for now. I have struggled with valve adjustments though. Seems like a few always up out of spec, but it doesn't seem like it's always the same one. It's on the list to go back and recheck. I've spent probably 10 hours combined total adjusting valves this past month lol.

 

something else to think about

 

 

Plugs and wires are new, plug order is correct. Knock sensor is new. Fixed exhaust leak. Coolant temp sensor seems okay. 180s max. Intake air temp is high though. I see anywhere from 130 to 150 when first starting the car.

Seems to be restricted exhaust flow. I looked into the cat from the front, I didn't see any crumbling honeycomb or anything, but my vacuum drops to zero when goosing or WoT. Fixing the exhaust leak seemed to change the voltage flow of sensor 2 o2, but it still really moves around a lot. Now I have to decide if it's a plugged cat or plugged muffler. Any tips on how I can do that short of taking them off? I sent have the tools to do so.

 

time for hiflow cat and catback exhaust

 

Had a similar issue years ago. The more gas I gave it, the more it bogged. Then it would take off all of a sudden. The cat guys had come undone and clogged the exhaust intermittently

 

hey guys sorry to add onto the thread but I have a question that relates to misfiring and loss of power. The freeway entrance by my house is shaped like a loop. at first when I'm driving everything is fine, but once I start turning the car and pressing the acceleration pedal, the car doesn't accelerate and the engine revs like as if its in neutral, so the car starts to slow down and everyone begins to honk at me because they probably think im being an ******* and revving the engine when all i'm trying to do is get on the damn freeway. anyways when it straightens out, it kicks into gear and it starts to accelerate. any info on what could be causing this would be much appreciated. Again, when I go into a loop and start to accelerate, the engine revs and the car doesn't accelerate until it starts driving in a straight line. thanks everyone :D

 

That sorta sounds like your axel or CV joint has an issue. Popping out when turning the wheel maybe. Does it do it both directions or only right? I'd turn it whatever direction the issue occurs while on stands and inspect that.

 

to be honest I make wide left turns and U turns and I don't notice anything, its when I turn right. for sure thanks for the info!!! will look into it