K2dulce

I have a 99 civic ex coupe the catalytic converter went bad and the car had been running pretty bad I got it replaced today as well as the 02 censor and the car is still running horribly ie: idling so low when at a atop it's close to cutting off, and the engine dragging once I reach 50 mph and knocking really hard at 60mph what could be the problem

lazlong

Any codes? Are you getting fuel and spark? Is it getting clean air?

K2dulce

Yesterday I took it to auto zone I'm not sure what the codes were but everything u asked about is what the man said the problems could be. He said it was misfiring on all cylinders it could be my spark plugs the spark plug wires or some type of air control piece under my hood that costs about $168 how do I know which one it is though? I bought the spark plugs cause they were the cheapest to replace And I figured I would start at the bottom and see if the problem persists

lazlong

The code should point in the right direction. Need exact codes to be able to tell.

Most of your questions can be answered by the service manual. Find MelJ and download the manual from his sig.

If you still have questions post back.

*The mis-fires are probably why the cat went bad, don't drive it if you don't have to 'cause you risk ruining the new cat.

K2dulce

Whatever the misfires were is it possible they could ruin the cat in this short a period of time? Because I never figured out what was wrong (causing the misfire) and am now having the same symptoms seems like my cat is bad again

lazlong

I've seen them go bad in a month.

K2dulce

Ok thank you so much

ezone

I have seen them "go bad" (more like completely freekin' ruined) in only a matter of MINUTES. All it takes is a bunch of dead misses. Raw fuel gets burned in the cat, making it overheat. The overheating causes physical damage inside the cat.


A glowing red cat is likely to be trashed.
Misfires and raw fuel kill cats.
Hondas cats are cheap. Try this with $1000+ cats and see how happy a customer is.

To the OP:
There is a reason the book says not to drive the car when the CEL is flashing. (RTFM)
The cat was only a symptom, not the problem.
Whomever decided to replace the cat should have fixed (or recommended to fix) the running problem first.
Maybe the person that only replaces cats depends on repeat business.

lazlong

Mine is $800 at Majestic. K2dulce's is $650. Not exactly cheap.

Gunner

What were the codes? Can you get the codes again..Before you spend more money on another cat you should figure out what is causing it...IMO

ezone

Your cat looks like it retails at almost a grand. I was thinking of the cat that's part of the manifold that retails for about $660.
I should have said multiple cats worth multiple thousands of dollars in that other post.
I spent some time working at a high line Euro dealer some years ago.
Honda prices seem cheap to me by comparison for just about anything.

K2dulce

I can't get the car somewhere to be plugged up because it only allows me to drive 25-30mph then starts over heating and hissing (while heat gauge passed where it normally would be so I pulled over) so I don't have any codes at this point

ezone

Get under the car and disconnect the exhaust pipe at the bolted joint in front of the cat. That will make it LOUD but driveable. (Assuming the cat is the blockage).
Use some coathangers to wire up the cat so it doesn't drag the ground.

K2dulce

Ok I'll try that then get the car to nearest place that can plug it uP and give me the codes which is about 10 miles away

K2dulce

The cat was welded on so we drilled holes instead and the codes are p1509 and p0420

ezone

Soooo....did drilling holes in the pipe allow the car to drive better than before? If it did, then the cat has come apart inside or clogged.
If not, then there is something else going on.

Was this scan done at a parts store or a mechanic?
P1509 is IAC valve circuit
P0420 is cat efficiency

The IAC code can make the idle very slow and want to die at stops. That alone shouldn't kill a cat. A couple possibilities are a bad IAC valve-- electrically bad, disconnected wiring, the PCM, and maybe the wires for the valve got swapped with another component nearby during some engine work (that is only a slim maybe, I have seen other components--TPS and MAP-- with swapped wires that didn't set codes but ran absolutely horrible).

The knocking noise bothers me. Is it coming from the engine? Look in this thread for the video, see if it sounds like your noise: https://www.civicforums.com/forums/2...driveable.html
This one has a rod knock. Needs an engine. Hope your engine doesn't sound like that one.

Poor running conditions can kill cats in a hurry. Raw, unburned fuel kills cats. Rich running can kill a cat. Oil burning can kill a cat. Anything that causes the engine to run poorly can kill a cat.
Problem is, some people can't tell that there is any sort of problem with their appliance (car) until it can't move under its own power anymore.
If this describes you, then maybe it is time for professional help.

A clogged exhaust (usually from a clogged cat or when the cat elements came apart inside) can make the car overheat, hiss while trying to accelerate (backpressure), run hot, and limit your road speed. All because the engine can't breathe. Mechanical problems and poor engine running can do the exact same things, AND lead to ruining the cat on top of it all.

K2dulce

I have had the iacv, map sensor, spark plug wires, spark plugs, alternator, cap, and rotor replaced and the car still idles really low and misses at about 1500rpm. Also the check engine light is still on and reading iacv.

ezone

Someone needs to diagnose your problems then.

lazlong

There's probably something wrong with the IACV circuit then. Do you have a multimeter and know how to use it?

K2dulce

Ok someone like who or where?

K2dulce

No what's that and what does it do

ezone

Someone at a real shop that really knows what they are doing, can truly diagnose a problem, and doesn't just fire the parts cannon at a problem.

You already fired the parts cannon and it didn't solve your problems, correct?

Handy pic of a parts cannon: