newer catalytic converter plugged

[Guest dpannell]

What engine problems could cause a converter to plug in only 13000 miles? I had mine replaced February 08'...it quickly plugged in the last two days. There is NO exhaust at idle. The "counter" mechanic at CarX instantly blamed it on the engine.

I have no codes...and the engine ran strong, smooth and efficient prior to this issue. Anyone with similar experience? Dave

[Guest ekvh]

Have you meddled with the emissions systems in any way that could make it run leaner and therefore hotter? More likely it is defective unless you still can get leaded gas.

[Ronnie]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: dpannell</div><div class="ubbcode-body">What engine problems could cause a converter to plug in only 13000 miles? I had mine replaced February 08'...it quickly plugged in the last two days. There is NO exhaust at idle. The "counter" mechanic at CarX instantly blamed it on the engine.

I have no codes...and the engine ran strong, smooth and efficient prior to this issue. Anyone with similar experience? Dave </div></div>

Dave, two things come to mind. An engine that is using (burning) oil will cause the converter to clog up. Another thing would be a bad O2 sensor causing a rich fuel mixture that would not burn completely and cause the converter to clog due to carbon build up. The ECM would not set a code because the it would see a correct mixture based on the incorrect data it would be receiving from the defective O2 sensor.

Do you see black or blue smoke coming out of the exhaust? Blue smoke is usually oil smoke, black smoke is usually caused by a rich mixture.

[Guest Mike_s]

I second what Ronnie said and will add that I've heard that a overly rich mixture can cause higher than normal converter temperatures which can cause the honeycomb structure inside to break apart which then clogs the converter

[Reatta45]

I’m with Ronnie on this… Too rich in fuel or oil.

Could be from lots of very short trips not allowing things to get to operating temp or bad ox-sensor, also could be engine oil or trans fluid, but definitely too rich. KennyV.

[Guest simplyconnected]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: dpannell</div><div class="ubbcode-body">What engine problems could cause a converter to plug in only 13000 miles? I had mine replaced February 08'...it quickly plugged in the last two days. There is NO exhaust at idle. The "counter" mechanic at CarX instantly blamed it on the engine... Dave</div></div> Converters fail for many reasons. If you didn't introduce leaded gasoline, or your engine isn't suffering from oil leaking into the cylinders (usually from old-leaky valve seals at startup), they usually fail because of ignition misfire or a leaky exhaust valve that has been allowing unburned fuel to enter the exhaust system. When that unburned fuel hits the converter, it ignites, sending the converter's operating temperature soaring over 3,000*F, melting the honeycomb substrate that supports the catalyst, creating a partial or complete blockage. If you ever took a blocked substrate apart, it looks just like a brain, with no evidence of honeycomb.

If you simply replace a plugged converter, it will temporarily restore free breathing, but unless the cause of the converter failure is also corrected, chances are the replacement converter will suffer the same fate.

Catalytic converters rely on proper mix of exhaust gases at the proper temperature. (This is where functioning oxygen sensors come in.) Bad exhaust valves or fouled (missing) plugs cause unburned fuel to overheat the converter. The over-use of certain additives can cause the mixture or the temperature of the exhaust gases to change, ruining the catalytic converter; so can the use of leaded gasoline.

Hope this helps. - Dave Dare

[Guest steakneggs]

Maybe you can get the exhaust gas analysed like they do at emissions testing. If you have any exhaust. Steak

[Guest simplyconnected]

By the way, out of curiosity, how many miles do you have on this engine?

[Guest dpannell]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ekvh</div><div class="ubbcode-body">Have you meddled with the emissions systems in any way that could make it run leaner and therefore hotter? More likely it is defective unless you still can get leaded gas.</div></div>

Guys,

I did lose the throttle position sensor mid-july....but replaced it and set it exactly as the old one was. (.38 closed throttle to 4.42 @ wot) I also "use" a little oil....near 1/2 quart @ 3000 miles. It is a 170000 mile engine but runs as smooth as possible idling and always gotten decent mileage. (upper 27's on the road)

I was concerned by the mere size of the newer converter when they replaced it....about 1/3 size of the original....but "they" assured me it would work equally as well.

I really hate to put another converter on it without discovering the real issue.......

Dave

[Guest F14CRAZY]

I'd weld/clamp in a straight pipe as a temporary measure and see how it does without a cat. If your engine is indeed burning too richly for some reason or another, or consuming oil, you'd have an easy way of seeing it in the exhaust without a cat to burn it up before it exits

[Guest simplyconnected]

170k? Use the 'test' pipe. 1/2-qt / 3000 miles sounds ok, but it makes a difference HOW oil gets used. Do you get smoke when you first start it? Or, does it use oil all the time?

Oxygen sensors are designed to last 50k. Have you ever changed them? When the O2 sensors are cold or go bad, your computer uses a subroutine in its program, that makes sure the engine isn't running lean. In other words it makes the mixture rich until the O2 sensor starts reporting. After you change sensors, your fuel economy will improve, making the sensor pay for itself

I wouldn't worry too much about a short-term bad throttle position sensor. I had one go bad on a Pontiac Transport. The ABS was going nuts, and I couldn't get up to 60. The engine ran like crap until I changed it.

[Guest dpannell]

I changed the O2 sensor at 144000...icm around 155000 plugs and wires @160000.....then TPS at 167000 and I've really never noticed any smoke...black or blue at startup or otherwise. Is it possible the O2 sensor went bad that quickly? 80% of my driving is highway. I'm hoping this converter was just failure prone..... Dave

[Guest simplyconnected]

Dave, they aren't prone to anything. Owens-Corning makes these substrates for the auto industry. They're glass, basically, doped with precious metals. When you see one it looks like a brick, and it's that hard. They just sit there and heat up from hot gasses flowing through. If ANYTHING hits it that can burn, it does, raising the temperature even more. That's how they work, they burn off anything that didn't burn in your engine.

Look, did you ever change halogen headlight bulbs? If you don't wipe ALL finger oil off with alcohol, the oil will trap the intense heat, and MELT the glass, for an early demise. Motor oil melts the glass substrate, too. So will unburned fuel.

O2 sensors are done-in by silicone and leaded gas. Using leaded gas, new O2 sensors only last about 13 runs at the circle track. Other than that, they are nearly indestructible. We test by heating them with a propane torch, then we measure for voltage on the wires.

I suggest you use the 'test' pipe until you can find the source of your converter eater. Any engine 170k-old, is going to be more inefficiant (worn & sloppier) than when it was new. 170k exhaust valves most certainly leak far more than they used to. Driving highway most of the time is a good thing for your system.

[Guest ekvh]

I just posted this on another topic. I put in a new O2 sensor two weeks ago. I noticed a slight increase in mileage. In my second tankful, I noticed a drop in mileage. I thought it was from driving into a headwind, but yesterday it was still there with no headwind. I switched to the diagnostic mode and saw my new O2 sensor was reading 0.00 to 0.01 at 60 mph. Below 40 mph it would fluctuate with normal readings. I looked around and checked connections to see why it would be running full rich. ( I deducted it was full rich because if the O2 was reading that lean, my mileage would read fantastic, but it was only 20 mpg. To shorten the story, I had kept the old O2 sensor in the trunk, so with some burned fingers, I put the old one in... Mileage and O2 readings back to normal! I will return the "new" sensor while still under warranty on Monday. I doubt that would have been caught that quickly with any other car than the REATTA!!!

I just put in the replacement yesterday. I haven't driven it that much yet.

[Guest simplyconnected]

Good job, ekvh! There's proof of how O2 sensors save gas, cut emissions, prolongs cat converter life, and pays for itself. When they work correctly (heated), O2 sensors produce a voltage (rich:~0.8V, lean:~0.1V, and norm:~0.45V). The computer reads that input and adjusts fuel injectors output, to match the perfect Air/Fuel ratio to 14.7:1. As you can see, there is no steady state, but rather, a constant 'hunting' back and forth from slightly lean to slightly rich, regardless of altitude and temp. Brilliant, actually.

[Guest ekvh]

Brilliant,.... it keeps us from changing anything unless you can modify the entire computer system. It locks the cars performance right up, and limits the backyarders who were beginning to make inroads into the auto industries' stranglehold. It has pretty much eliminated for 25 years the guys who were ready to deliver us the option of high performance or high economy. I am still trying to figure out the danger involved in trying to run the car a bit leaner than factory settings. I am still reading on these hydrogen-from-water scammers. I am wondering if they are simply tweaking the system enough to get them to run on ultra lean and risk ( and probably do ) burn up their motors. If you tweak the signal from the O2 sensor, the MAF goes nuts and adds fuel. If you tweak them both, the timing is changed. Or if you switch them too far from normal you are automatically pushed into closed loop. When the vehicle goes into closed or open loop, we are pretty much out of the loop. I have been reading that the newer Honda ultra miler models have leaned the mix to as high as 22:1 from the standard 14.7:1 that we are stuck with.

As to the O2 sensor. How many mechanics out there would have "thrown money" at my car assuming the O2 sensor was good because it was new??

[Guest dpannell]

OK.... the problem did turn out to be the O2 sensor failing. It locked into a voltage of .997 sporadically and for several minutes at a time. It was apparently just "dumping" unburned gas at the converter. I replaced it and now see voltages of .12 to .78 .

I assume that due to the fact it was still providing a voltage signal I received no codes.

I've replaced the converter with a new one and will continue my monitoring......

This brings me to another question.... Should the TPS reading be different at closed throttle without the engine running, than it is WITH the engine running? And why or what could cause it, or be the result of allowing it to continue?

Dave

btw...as expected I have already seen a HUGE increase in mpg.

[Guest simplyconnected]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ekvh</div><div class="ubbcode-body"> I have been reading that the newer Honda ultra miler models have leaned the mix to as high as 22:1 from the standard 14.7:1 that we are stuck with.

As to the O2 sensor. How many mechanics out there would have "thrown money" at my car assuming the O2 sensor was good because it was new??</div></div> I will be very happy to stick with 14.7:1 A/F ratio. Let Honda do 22:1, I don't care. All I know is, I burned a hole right through #1 piston driving from Niagara Falls to Detroit in the wee hours of the morning. My car was smoking so bad, the border guard just waved me on, into Detroit. It was all caused by running too lean.

Another point is, all your sensors can be checked with a meter, including your O2 sensors. As far as your Throttle Position Sensor readings are concerned, it doesn't know or care if the engine is running. It reports throttle position (your gas pedal) by changing resistance, much like your gas tank sensor. Again, all these components can be checked for good/bad with an old, cheap, meter.

[Guest dpannell]

Simplyconnected,

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: simplyconnected</div><div class="ubbcode-body"> As far as your Throttle Position Sensor readings are concerned, it doesn't know or care if the engine is running.</div></div>

It apparently does seem to know/care.......If I read the ed01 with the engine NOT running I see .38 , with the engine running it displays .40 . I understand these numbers are within normal operating parameters but what may cause the difference?

My thinking is I may avoid some additional repair expense if I "head it off at the pass" My 2nd new converter cost me ~$200 installed ( I don't do exhaust work ) because of a part that cost less than a $100.

Dave

[Ronnie]

The difference could be this: When the engine is running and the alternator is operating the voltage in the electrical system may be slightly higher than when the engine is not running. If the sensor has a higher input voltage there may be a higher output voltage.

[Guest Mike_s]

Dave,

I'm curious, do you know how the converter failed? clogged with carbon? damage from high temps?

[Guest ekvh]

I am curious as to how you know you were running lean from Niagra F to Detroit? Had you modified anything? Or was it the result of a sensor malfunction?

[Guest simplyconnected]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Ronnie</div><div class="ubbcode-body">The difference could be this: When the engine is running and the alternator is operating the voltage in the electrical system may be slightly higher than when the engine is not running. If the sensor has a higher input voltage there may be a higher output voltage.</div></div> Exactly. Not running, your battery settles down to 12VDC. Running voltage is 13.5vdc.

We're only talking about two/one-hundreths difference.

[Guest simplyconnected]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ekvh</div><div class="ubbcode-body">I am curious as to how you know you were running lean from Niagra F to Detroit? Had you modified anything? Or was it the result of a sensor malfunction?</div></div> This was in the late 1970's (and not in a Buick). Back then, cars used carburetors, cast iron heads, and they raised the engine temps for a more complete combustion. We also had profound run-on and pre-ignition. (Later, aluminum heads straightened all that out.)

It was sad to see our cars continue to run five minutes after taking the key out. Pre-ignition was evident with piston-clack in varying degrees. On a long trip with the car loaded with the four of us, preignition literally burned right down the side of my #1 piston, exposing oil to the combustion chamber, and hot gasses to the oil pan. It started smoking real bad. I had no choice but to keep going as the engine temp was good and so was oil pressure. I drove twenty miles billowing smoke like a train.

I pulled up the driveway, and the next day I pulled the engine, right where it sat. I bought 11:1 compression ratio TRW aluminum pistons, ran premium gas, but I ran it rich at 180*. That move turned a "ho-hum" engine into a trailer-puller with plenty of passing power on the highway.