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Devin

Clogged Up Cat?

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Symptoms:

  • Terrible Gas Mileage (5 mile trip - about 1/2 down to 1/4 tank)
  • Very Slow Acceleration @ Full Throttle
  • Engine Gets Hot Quick

Now, I have these issues, and I have had them for both my old engine and new. So I thought about it, and I thought maybe it was a clogged up catalytic converter. Makes sense (to me at least). I replaced the O2 sensor before the cat, but nothing got better.

But now that I have this new engine, I think a little more, and this seems to piece together. I may be way off, but it's just a thought.

A clogged up cat would cause a ton of back pressure on the motor, right? This makes it work harder, heating up quicker. This also means that when I floor it, the exhaust has nowhere to go but back into the engine. If anybody recalls my last engines issue, I discovered I cracked the head. Could this have been because of the back pressure?

I really don't want to kill my new motor, so if anybody could chime in here, it might mean my cars life or death. :P

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Yes, you very well could have a clogged up catalyst.

One thing to listen for, is if the engine makes a sort of exhalation noise when you shut it off. Just like it is breathing out......because it would be.

They do make an exhaust backpressure gauge, which screws into the 02 bung, which is the best way to tell. You should have about 1 psi backpressure.

Another way I have used before, is to feel the exhaust coming out of the car after it is warmed up. If it doesn't have good flow, it will feel weak, and be hot enough to melt lead ingots.

Then, the last way is to pull the cat, and hollow it out, and put it back on. Although, I only recommend this for testing purposes.

Tim

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Another method to check whether an exhaust may be plugged is to use intake vacuum.

Connect a vacuum gauge to a vacuum port on the intake manifold. Start the engine and check the reading at idle. Normal vacuum at idle is about 18 to 21 inches Hg. Increase engine speed to 2,500 rpm. The vacuum reading will drop, then return to close to the idle reading. If the reading is significantly lower or continues to drop, it might indicates a buildup of back pressure. There are other problems that could cause the vacuum readings to be off, so this is only one test. You should still do a back pressure check.

The back pressure problem may very well be contributing to the codes you have.

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"vacuum port on the intake manifold"

Where is this located? Sorry, don;t know the locations very well yet.

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"vacuum port on the intake manifold"

Where is this located? Sorry, don;t know the locations very well yet.

There should be several fittings on the intake manifold that have vacuum lines attached (like the vacuum line to the brake booster). You could remove any of those lines for this quick test.

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Could I just remove it? A new one is kinda expensive, and I'm struggling to even pay the car insurance each month. Any bad effects of no cat?

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You won't pass emissions.

We don't have emission testing here in Michigan. ;) Or car inspections at all for that matter.

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Could I just remove it? A new one is kinda expensive, and I'm struggling to even pay the car insurance each month. Any bad effects of no cat?

:wacko: It is illegal under federal law to disable any of the emissions equipment. You decide.

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:wacko: It is illegal under federal law to disable any of the emissions equipment. You decide.

The probability of getting caught is less than that of successfully navigating an asteroid field.

And, technically, if the cat is plugged it's probably already not functioning properly, so the cat has already disabled itself. It broke the law, you're just punishing it by having it melted down. ;)

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Plus, I'd just say I didn't even know it didn't have one. I'm good at playing Mr. Dumb and Innocent. ;)

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The probability of getting caught is less than that of successfully navigating an asteroid field.

And, technically, if the cat is plugged it's probably already not functioning properly, so the cat has already disabled itself. It broke the law, you're just punishing it by having it melted down. ;)

:rofl2:

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Then, the last way is to pull the cat, and hollow it out, and put it back on. Although, I only recommend this for testing purposes.

Tim

I WAS trying to drop a subtle hint, LOL

Tim

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I WAS trying to drop a subtle hint, LOL

Tim

If the catalytic converter is the issue, that's what I'll do.

Although a clogged/dirty EGR matches as well. ;)

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I WAS trying to drop a subtle hint, LOL

Tim

Coat hanger wl work. Lol

tim we are toooo old for hints.

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I LOVE old posts...
Just have someone keep the car running by keeping their foot on the throttle while feeding water into the intake,,, it will turn to steam and clean out the cat.   the more water you run through it the

better

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What??? Water? Engines don't run on water. Heard of hydro lock???

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Using sand in place of water has much better effect.

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Make sure you mix the sand with gasoline first to give it a nice flowing mixture.

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That sand gives a machined finish right????

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That sand gives a machined finish right????

 

Easiest way to hone the cylinders.

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Symptoms:

  • Terrible Gas Mileage (5 mile trip - about 1/2 down to 1/4 tank)
  • Very Slow Acceleration @ Full Throttle
  • Engine Gets Hot Quick
Now, I have these issues, and I have had them for both my old engine and new. So I thought about it, and I thought maybe it was a clogged up catalytic converter. Makes sense (to me at least). I replaced the O2 sensor before the cat, but nothing got better.

But now that I have this new engine, I think a little more, and this seems to piece together. I may be way off, but it's just a thought.

A clogged up cat would cause a ton of back pressure on the motor, right? This makes it work harder, heating up quicker. This also means that when I floor it, the exhaust has nowhere to go but back into the engine. If anybody recalls my last engines issue, I discovered I cracked the head. Could this have been because of the back pressure?

I really don't want to kill my new motor, so if anybody could chime in here, it might mean my cars life or death. tongue.gif

 

The insides of catalytic converters can become brittle, break up in to chunks, get blown out then trapped in the muffler. Pounding on the cat with the side of your fist will tell you if the catalyst has broken loose (you'll hear it rattle) from its shell and is starting to break up. If it does rattle you'll need to replace it.

You can also grab the mufflers tail spout and give it a shake. If you you hear anything from inside (rust or converter stuff) you'll need to replace it also.

Edited by CowzRule

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Been there, done that. We removed the third catalytic converter and replaced it with a straight pipe about a month ago. Until today, absolutely no problem. Oh well.

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Been there, done that. We removed the third catalytic converter and replaced it with a straight pipe about a month ago. Until today, absolutely no problem. Oh well.

Did the sound change much with the swap?

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