Catalytic Converter

[BoogerBurns]

Well they replaced it with a weld on one. This is how I did on the emissions (Georgia)
25/25 test
HC ppm 92 allowed 189
CO % 2.28 allowed 1.21
NOx PPM 923 allowed 1374
CO +co2 16.0 6.0 (min) allowed

50/15 test
89 194 allowed
2.76 1.10 allowed
698 1504 allowed
16.2 6.0 (min)allowed

So should I replace the CC or change the o2 and hope its just that? I re hooked up the EGR and it seems to be ok, taking a vacuum pump to it tomorrow.

[Vanilla Sky]

I would go with the O2 sensor first. After it's replaced, drop a can of Seafoam into half a tank of premium and run the crap out of the car for a while. Fill up with premium again, warm the car up really well with a freeway run then take it in for testing. That will probably clean it up.

[Dr_Snooz]

Sorry, I'm having a little trouble reading your results. Were you high on CO? If so, I'd at least run through the O2 sensor troubleshooting section before springing for a new one. Also check the obvious: tune up, good gas, etc.

[ecogabriel]

Hydrocarbons are within range but high as long as I remember my own tests in GA.
Same for NOx; within normal range but on the high side.

Definitely check O2 sensor and replace if it had more than 50K miles. In case of doubt, replace it as it is relatively inexpensive.

It seems that you might be burning too much gas; that's bad because excessive fuel in the exhaust may destroy (melt) the guts of the cat converter.

In the meantime you may read this:
http://www.aircare.ca/repinfo-ere-causes-co.php

I had better links but I cannot come across them.

I assume you have an EFI Accord right? How many miles? Is it running fine? Does it misfire?

[Vanilla Sky]

LXi, it's in his profile.

[ecogabriel]

some further reading

http://www.aa1car.com/library/2000/ic60032.htm

[ecogabriel]

LXi, it's in his profile.

right after posting I saw his signature... I'm shot at this time!:thumbdn:

[ecogabriel]

I found the test on my computer; just cut the part with the results. It was done last March. Car had almost 132K at that time; cat converter is probably OE, EGR valve working

[img=http://img22.imageshack.us/img22/9860/testdql.th.jpg] (http://img22.imageshack.us/i/testdql.jpg/)

How many miles on your replaced cat? It should be fine unless some malfunction ruins it. Typically, excess fuel (or burning too much oil) would cause the cat to raise its temperature too much and ends up melting it inside.

[BoogerBurns]

yeah its efi. and its got 287k on it. It runs great! did a tune up in the past couple days. spark plugs, fuel filter, air filter, oil change, o2 sensor, brake pads, changed the radiator and fluid.
I found out that the wire for the o2 had been cut. so I put a new one on and wired it up. Its not running rough of anything. IDK how many miles on the cat, i just bought the car for 700. :) Sorry for not getting back sooner, I have been working on the car and stuff.

[BoogerBurns]

oh btw it was high co

[ecogabriel]

So, you found the O2 sensor wire cut, but the PGM_FI light was not turned on right? Did you have any codes flashing in the ECU? Strange...

Without O2 sensor signal the ECU has to default to a predefined setting that uses more fuel. With the sensor connected and working it should bring CO and HC down.
Make sure you drive it at speed for a while before testing to bring the cat to temperature. Those cats are so far down the exhaust that they take a while to get to temperature.

[BoogerBurns]

yeah its pretty back there, so ill do that, ive put about 100 miles on the new o2. so I think its good to go. Just need it to dry out here.

[ecogabriel]

So you did have the sensor effectively unplugged but the ECU did not flash a code. I had mine disconnected for a while and same thing happened (no code).
I even posted here because I found strange that whatever other sensor was unplugged the ECU would flash a code immediately but not with the O2;
I was stoned a little bit for posting about something for which I supposedly knew the answer.... anyway
There is something going on with those old ECUs because once mine got connected back and fixed a temperature problem (stuck open thermostat+gauge sender working erratically) apparently the ECU entered "closed loop" and fuel consumption improved markedly especially on highway driving.
Make sure that your car gets hot enough to enter closed loop.
Then please post back to see how it went...

[BoogerBurns]

A lot of people will flame you for asking questions like that. But anyways, its cause the ECU doesn't do much in the way of controlling things. that started in OBI nad went realtime in OBII.

[Vanilla Sky]

Yeah, the only thing that our ECUs control is fuel, and if it's an 88 or 89, it controls the opening of the secondary runners in the intake manifold. OBD1 added spark control.

You could always 'Squirt the car and scrap your OBD0 crap.

[ecogabriel]

Well, the ECU should tell when an sensor is unplugged; if one sees the description for ECU codes it would tell that. Besides, the '89 manual available somewhere here tells the procedure for checking a "code 1" and includes controlling the wiring.
My ECU seems to know when other sensors are unplugged, but apparently not when the O2 sensor is unplugged... Well, boogerburns' ECU did not know that it was running without the 02 sensor unplugged.

Oh, 86-87s ECU have some control over distributor advance. With engine cold they act a solenoid that actuates the distributor vacuum advance. That is why the vacuum advance has two hoses coming to it; no question OBD1 is better doing away with all the mechanical devices for advancing spark.
Back to my failed question, what is wrong with asking something that looks obvious but it is not so obvious? The sensor was unplugged and the light that supposedly should warn about it did not do it; plug the sensor back and everything works fine. Something is missing there... If it is a bug with the ECU that's fine with me; I just wanted to know
Well, I'm getting too philosophical; let us know how the retest goes.

[BoogerBurns]

I passed but barely. The cat is going bad. But it can wait another year!
And 86-87 only have 1 o2 sensor. And all it does is sends a signal (in voltage) to the ECU, if it doesn't see it, or the voltage is out of range, it just does its own thing. Like dump a lot more fuel into the injectors to overcompensate.
It doesn't necessarily have to throw a code. It might store one. But doesnt mean your car wont run without it.

Also, 88-89 Have a slightly different intake, and better ECU and 2 o2 sensors. Im not sure what else is different. Correct me if I'm wrong.

[Dr_Snooz]

How did you arrive at the diagnosis of a failing cat?

[ecogabriel]

I passed but barely. The cat is going bad. But it can wait another year!
And 86-87 only have 1 o2 sensor. And all it does is sends a signal (in voltage) to the ECU, if it doesn't see it, or the voltage is out of range, it just does its own thing. Like dump a lot more fuel into the injectors to overcompensate.
It doesn't necessarily have to throw a code. It might store one. But doesnt mean your car wont run without it.

Also, 88-89 Have a slightly different intake, and better ECU and 2 o2 sensors. Im not sure what else is different. Correct me if I'm wrong.

can you post test results?
If it is the CAT, a direct bolt-on should not go that much above $100; you'll swear a lot getting the rusted bolts out though

Well, the troubleshooter for ECU code 1 calls for checking the wiring (among other things); it is odd that when there is a wiring problem there is no code set in the ECU; the LED in the ECU in my case did not flash (yours did not too, did it?).
Anyway, as you said if the ECU does not see signal it just uses a default value for fuel. yes, 88-89 have different intake (a wonderful two-stage) and a different exhaust too... 10 extra horses..

Please post test results; glad you passed.

[BoogerBurns]

My ECU is working just fine, and so is the PGM-FI light. It did not turn on. And the 15 mile an hour test is what really got me. I was 1.05 and the allowance is 1.10, that's what lead me to thinking the Catalytic converter is bad. Couldn't be anything else now. I was GREAT on everything else!

[Dr_Snooz]

I'm not hugely stoked by the well-it-isn't-anything-else-so-it-must-be-the-cat method of diagnosis. There has to be a better way. The Bimmer cats start to rattle. I can deal with that.

[ecogabriel]

the 50/15 it seems to push the engine harder.
Still, CO went down from 2.70ish to 1.05 right? Were all the other numbers that close? You may be right about the cat considering the car's mileage. But since you passed you do not need to worry about it right now

[BoogerBurns]

Yeah, Im not worried about it, but DR. Snooz, it couldnt be anything else! I replaced the spark plugs, the egr lifter sensor, the vacuum hose, the U tube, the air filter, the oil, and oil filter, and some other stuff. Its got to be that.

[Vanilla Sky]

Could be the EGR passage clogged, could be a break in a wire somewhere, could be a broken vacuum hose. Lots of other things it could be.

[Dr_Snooz]

Yeah, Im not worried about it, but DR. Snooz, it couldnt be anything else! I replaced the spark plugs, the egr lifter sensor, the vacuum hose, the U tube, the air filter, the oil, and oil filter, and some other stuff. Its got to be that.

Sorry, I didn't mean to sound critical. I ask because I'm hoping someone will have found a good way to diagnose bad cats aside from spending a fortune to replace everything else first and not having it work. Basically, I don't want to have to do that myself.

[ecogabriel]

Sorry, I didn't mean to sound critical. I ask because I'm hoping someone will have found a good way to diagnose bad cats aside from spending a fortune to replace everything else first and not having it work. Basically, I don't want to have to do that myself.

Unfortunately, it seems that even the shops do that. Unless one can measure exhaust contents before and after the cat it would be impossible to tell the cat is bad except if mechanically damaged (rattles, meltdown). Serious guys would look to repair whatever other problem there may be and rule out anything else before concluding the cat is bad.

[BoogerBurns]

Yeah, pretty much I did everything BUT replacing the cat. So it has to be that. But its not effecting my performance yet, its ok. And I get it Snooz, dont worry, I hear what youre saying. I dont want to either.

[Vanilla Sky]

That's what a "test pipe" is for.

[BoogerBurns]

What is this test pipe for?

[Vanilla Sky]

It's to test to see if a cat is clogged.

[88Accord-DX]

I'm hoping someone will have found a good way to diagnose bad cats aside from spending a fortune to replace everything else first and not having it work. Basically, I don't want to have to do that myself.
What you do is drill a 1/4" hole in front & after the cat. Then you get a vacuum/low pressure gauge with a cone shape fitting on the end. Shove the fitting in the front & rear, write down readings. You shouldn't have no more than 3 p.s.i. of backpressure before that cat. You can also feel with your hands any difference in pressure. If you feel more backpressure in the front than in the rear, the cat is partially clogged.

[BoogerBurns]

Sounds like its easy! Ill try that whenever I need to do something with it. Thanks for the advice!

[Dr_Snooz]

What you do is drill a 1/4" hole in front & after the cat. Then you get a vacuum/low pressure gauge with a cone shape fitting on the end. Shove the fitting in the front & rear, write down readings. You shouldn't have no more than 3 p.s.i. of backpressure before that cat. You can also feel with your hands any difference in pressure. If you feel more backpressure in the front than in the rear, the cat is partially clogged.

That'll work! How do you seal the holes though?

[88Accord-DX]

How do you seal the holes though? That is where you would need a welder or take it to an exhaust shop & pay a few dollars to tack them shut.

IF you didn't have to have any kind of emission test done, you can run a straight piece of pipe straight through the cat if it's bad. Of coarse you'd have to gut it out first. The reason I say this, is because these cars don't have a downstream oxygen sensor.