AJMarshall

Hello all,

A few months ago, my '00 Integra started dying at random. It would just shut off as I was driving down the road, but after a few minutes, it would start and run fine again. After some diagnosis, the problem seemed to be electrical in nature. I started by changing out the distributor cap, plugs, and wires, which needed to be done anyway but did not solve the problem.

It took me several weeks and much trial and error, but I finally traced it to the ignition control module. During the diagnosis process, the CEL came on, which indicated a faulty O2 sensor. I figured the code might be related to the bad ICM, so I decided to wait on replacing the sensor. I replaced the ICM and reset the CEL. The car ran like a champ for about a month, but the CEL came back on after a few days.

Now suddenly, the car is demonstrating a loss of power on the high end. It idles fine (albeit a bit high at around 1500 RPM), and drives fine under light load, but when accelerating, attempting to drive at high speeds, or climbing hills, it has no guts. Concurrently, fuel economy is in the toilet, about half what I normally get.

I went to my local auto parts store and had them pull the CEL codes again. This time, it's reading the following:

P0170: Fuel trim malfunction Bank 1
P0420: Catalyst system efficiency below threshold bank 1
P0430: Catalyst system efficiency below threshold bank 2

Other relevant information:
-Fuel and air filters were recently replaced
-There is an exhaust smell coming from within the engine compartment
-No obvious vacuum leaks or damaged hoses, although I have not done a pressure test on them
-An odd high-pitched rattling sound sometimes comes from the front of the vehicle when accelerating

Based on what I've seen so far, my best diagnosis would be one of the following:

-Bad O2 sensor: But would this really cause such a dramatic loss of power? And why doesn't a CEL code indicate this?
-Obstruction in the exhaust system: I base this on the exhaust smell and the rattling sound. But would this cause the CEL codes I'm seeing?
-Lack of fuel pressure: Bad fuel pump or pressure regulator, perhaps?
-Something related to the new ICM: Not really sure about this, but the ICM is the one major component that has recently been replaced.

Also, I'm confused as to why one of the CEL codes refers to "Bank 2" on a 4-cylinder engine. Doesn't a "bank" refer to the cylinders on one side of the engine?

My next step is to test the fuel pressure, so I'll be visiting my auto parts store tomorrow to rent a pressure gauge. Other suggestions about possible causes and diagnostic steps would be appreciated.

Thanks in advance for any assistance.

AJMarshall

Update: Performed vacuum pressure and fuel pressure tests. The vacuum pressure is steady at 18 in/mg. Fuel pressure is 42 psi with the regulator vacuum tube detached, and 33 psi with the tube attached. All of these are slightly below the optimal readings, according to my Chilton manual, but not dramatically so.

Crxin2069

Are you Sure your cat is not plugged. Try running a test pipe to see or just run open headers to verify complaint of lack of power. It will be loud but you should be able to tell if that is the cause of the issue. Hope this helps.

wunfstgsr

Your O2 sensor is bad in fact i would suspect both are bad since it states BANK 2 which is the second 02 sensor which is pluged under the car bank 1 is the first sensor closest to the exhaust manifold.

Yes a bad 02 will give you bad mpg and performance.

Did you remove the distributor when replacing the ICM by chance? if so its possible you installed it back on and did not put it back where it was timed and your timing is now off.

Start with a new o2 sensor for bank 1.

AJMarshall

I'm not positive that the cat isn't plugged, but wouldn't that cause a gradual continuous drop in vacuum pressure as the engine ran?

I did not remove the distributor when I changed the ICM. Even if it were a timing issue, I would think that the problem would have showed up right away, but the car ran like a champ for a few weeks before the loss of power manifested.

I bought a new O2 sensor, so I'll change that out in the next couple days. We'll see what happens.

trm4life

You know what, I think it's simpler than that. Your ICM was absolutely the part you needed. When they get hot and fail they do what your car did. The newer integras have 2 o2 sensors. I'm willing to bet you could have a blown exhaust gasket around your cat, the rattle you hear is part of the o2 sensor adaptor. I could be wrong but take a look. If its leaking, the o2 sensor could be off because it takes 2 readings.

AJMarshall

I replaced the O2 sensor and reset the CEL codes. Drove it around for about 30 minutes. Some of the power is back, but it's not back to full strength yet. After a while, the CEL came back on, and it's posting P0420 and P0430 again.

Now I'm wondering if catalytic converter is clogged or damaged, but I would think that this would show up on the vacuum pressure test, would it not? There was no obvious damage to the gaskets on the cat when I looked at it.

Any suggestions about further diagnostic tests I might attempt? The cat seems like the most likely culprit at this point, but I'd like to be sure before spending the money and time to replace it.

trm4life

I'm going to assume, running with a bad coil, probably did a number on your cap, rotor, wires and plugs. Replace those...yes again if you already have. Because at least one of them is burned up. I personally refuse to use platinum plugs in my integra because it thinks they are delicious. Eat 'em right up. Other than that, without a cat at all you'd have most of your power. Yes, the o2 is for perfect air/fuel ratio. I still think you need to find where your exhaust leak is, if you have a smell in the cabin. Loss of exhaust pressure absolutely causes a lack of power. Other than that you have 2 o2 sensors! (at least I think all obd2 did i could be wrong) Have you replaced both of them?

supersilverdc2

X2 on the dizzy ICM...

this failing will cause you to shut off while driving .....

happened to me on a 7 lane section of freeway before the bay bridge... I was in the smack middle lane in the middle of traffic..... had to push the car to the side before the toll booth..... sucked *** real bad.....

Crxin2069

You can do a back pressure test on the exhaust to verify a plugged cat

wunfstgsr

Theres two 02 sensors, bank 2 is the last 02 on the cat, try replacing that..

AJMarshall

So I came across this video:
After watching, I bought a bi-directional scan tool and performed the test he outlined. Sure enough, the second O2 sensor voltage oscillated with the first O2 sensor, indicating a problem with the catalytic converter.

I pulled the old cat out, and it was trashed. All kinds of bits came tumbling out when I tipped it. One new cat and a few hours later, I'm running good as new again. I replaced the post-cat O2 sensor while I was at it, since it looks like it would be a real bugger to get out without removing the cat.

Thanks for the input, everyone.

Chargerhemi06

Your cat is done. Get a long pipe and hammer and gut it out. Then buy new O2 sensors.

wunfstgsr

Thats good ya found it was the cat, they can rot after a while, great idea on re[lacing the secong o2 that one is a pain to replace with the cat bolted up.