Check engine Code 1. Clogged CAT?

[HappyGilmore]

I noticed a gradual decrease in power from my 91 LX (F22A1), she is completely bone stock (engine wise). A few days ago my car would take quite a long time to get up to speed, say 10 secs from 0-25 MPH. At first I wasn't throwing a check engine light. The next day I got the same issue, this time I am throwing a CEL code 1, and nothing else. I even tried disconnecting the EGR to see if that would clear it up as the passages are known for getting clogged up sometimes (hell it is 23-24 years old lol). But then that also means I would have thrown code 43 as well and I didn't. Note the car has ran fine up until this point (She was always kind of a dog in the lower end, might have been due to it beginning to clog in the first place). Any ideas or input.

Thanks in advance!!!!

[accordztech]

A restricted exhaust may be the issue. Get a vacuum guage and hook it up. Note the reading. Raise to 2500 rpm. The readings shiuld be very close to the same. If u see a decline in the readings then its something in the exhaust.

Disconnect the cat first and do the test again. If it still does it then the restriction is in the exhaust manifold.

[accordztech]

But look up what code 1 is first.

[HappyGilmore]

Code 1 is O2 sensor.

[RyanD]

Code 1 is O2 sensor.

A clogged cat could still cause that due to inefficiency

[wagon-r]

A clogged cat is unlikely to throw an O2 sensor code. From the point of view of the engine, there isn't much difference between a restricted exhaust and a restricted intake. There simply isn't as much air going into the engine. The actual amount of air going into the engine is sensed by the MAP sensor and the ECU delivers fuel to match the air intake reported by the MAP. The only purpose of the oxygen sensor is to give a signal to the ECU as to how well the amount of fuel and the amount of air are matched up. The ECU responds to the O2 sensor signal and increases or reduces the amount of fuel. An O2 sensor code is thrown only if the ECU adjusts the amount of fuel - and the O2 sensor signal doesn't change. Actually, this is an oversimplification, but still the basic idea.

If you have an O2 sensor signal, its more likely that either the air/fuel ratio is off and the O2 sensor isn't working to correct it or you have a fueling problem.

[RyanD]

Well I learned something today. Rep for you sir

[accordztech]

A clogged cat is unlikely to throw an O2 sensor code. From the point of view of the engine, there isn't much difference between a restricted exhaust and a restricted intake. There simply isn't as much air going into the engine. The actual amount of air going into the engine is sensed by the MAP sensor and the ECU delivers fuel to match the air intake reported by the MAP. The only purpose of the oxygen sensor is to give a signal to the ECU as to how well the amount of fuel and the amount of air are matched up. The ECU responds to the O2 sensor signal and increases or reduces the amount of fuel. An O2 sensor code is thrown only if the ECU adjusts the amount of fuel - and the O2 sensor signal doesn't change. Actually, this is an oversimplification, but still the basic idea.

If you have an O2 sensor signal, its more likely that either the air/fuel ratio is off and the O2 sensor isn't working to correct it or you have a fueling problem.

Actually a MAP sensor only detects how much pressure is within the intake manifold. A MAF sensor (which we don't have) detects how much airflow is going into the motor. Air also doesn't go into the engine, its quite the opposite. Air pressure inside the engine is decreased/displaced due to the pistons going down and the intake valve opening, so since its displacing air then air is drawn into the motor.

The ECU uses the MAP to read the load of the motor and determines how much fuel to go into the injectors and a o2 sensor aids in telling how rich or how lean to make it. But yes you will get the code for the O2 sensor if the computer doesn't detect a change.

It can be that there is almost no air coming out of the exhaust system that it threw a code for the o2 sensor because there is no change. Leading to think that it can be a restriction within the exhaust manifold and not the CAT.

Best way is to diagnose is with a vacuum gauge, cheapest tool in the world and it will save you time.

[HappyGilmore]

I will deff check on that for sure. I also want to know why it drives like a dog. It seems like something is clogged. It starts and runs fine for 15 seconds, and then it runs like a slug, almost misfire like.