Thaik

As the title implies,

I have recently bought and installed a new catalytic converter for my DX/LX to EX Full exhaust swap. I did this in order to permanently solve a recurrent problem of cracked exhaust manifold.

Upon starting the car for the first time after the installation, I heard a buzzing/clicking sound coming from underneath the car when I rev the engine. The harder the rev, the louder the buzzing/clicking. As you may know, it is a catalytic converter mounted on the down pipe and not on the exhaust manifold.
The noise is coming from there.

During the first few kilometers, the engine felt great apart from the noise, it seemed to have better low-end torque and pulled better. But that only lasted for the first day.

As I drove the car for few other days, the engine exhaust note started changing and sounding a bit odd. As I rev the engine higher, I start hearing like a "boxy" noise, like engine sound is resonating within the front end of the exhaust from the cat back to the engine.

It really does pull better from stand still to 3000RPM but after that, the gas pedal is heavy and the engine seems to be working harder.

I've been running with a cracked exhaust manifold for quite some time and it didn't do that, apart from the leaking exhaust gas, power and engine sound were unchanged.

The catalytic converter itself is a Magnaflow Direct Fit for Civic EX 01-05 or Acura 1.7 EL (Same car basically).
The exhaust parts are stock OEM used parts apart from the Cat:
-Stock EX Header
-Stock EX Resonator
-Stock DX Muffler

Part number: 93228
http://www.magnaflow.com/02catalytic...irectfit=93228

I notice the exhaust pipe is slightly larger for the EX and the resonator is wider and longer too. The muffler is that from a Civic DX, my muffler. Piping is a bit narrower. Could this be the cause of the restriction?

I already replaced in the past my muffler with a cheap aftermarket one with a bad design causing lots of restriction (piping flatten), the muffler was vibrating a lot and buzzing too, but not in the same way, more like puffing. Even with that, the engine was running fine.

To sum up everything, I did a full exhaust conversion to EX exhaust (well, except for my muffler) and had to replace the Cat because the old one, the DX/LX with cat bolted with the header was cracked and cat was failing too (CEL P0420) and obviously because the swap needed that part to be complete.

Upon starting up, I heard a buzzing/clicking sound coming from the new cat as a I revved the engine, the harder the louder. Engine had better low end torque right away when I test drove it. Check Engine Light disappeared. The next days, it started having some restriction, heavy gas pedal when fully warmed up, weird "boxy" resonating exhaust note when revving higher than 3000 RPM, seemingly less power at high RPM.

It never happened with my previous cat-headers.

Now, does anyone has any previous experience with Magnaflow Cat or Magnaflow parts in general? I heard some bad stories about theirs parts on the net too, especially that buzzing sound, but not the restriction part.
The part is still within warranty and I would like to know if it is defective in any way.

I do not have check engine light at the moment, and I've been driving several hundred of kilometers already, but the engine performance and sound is degrading.

I don't know if this is supposed to be normal for a cat to be that restrictive, but I don't want to risk damaging my engine for having too much back-pressure.

Thank you in advance, it is greatly appreciated.

I will someday contribute back to this forum with some DIY of my own!

**UPDATES**
19/07/2014

CEL code: P0134
Sensor Circuit No Activity Detected (Bank I Sensor 1)
Removed Primary O2 Sensor DIY extension.
Cleared code.
Waiting to see if that solves it.

20/07/2014
Noticed increase in under hood temperature.
What used to be warm in the engine compartment is now burning hot!

Poopies

iTrader: (4)

I don't have any experience with Magnaflow (yet), but when I installed my new DC Sports header I broke one of the bolts connecting it to the downpipe. Whenever I would rev it to around 3k RPMs, it would sound like straight-up butt. Once I replaced both of the bolts, I never heard that again. Do you have any leaks coming from your new assembly?

kinakoes2

Did you make sure the mid pipe or cat was emptied of all packing material before bolting it in? Because if styrofoam was left in there...

Thaik

I think I did... I even took pictures of the inside of each end of the pipe. On the cat end, I could see the honey comb grills of the cat.

Thaik

After installing, I have double checked every bolt and torqued them properly.
There were no leaks the first day. I will check that again around the cat and around the O2 sensors.

Engine sound really sounds crappy. Lots of engine noise. Very noisy.

Thaik

Update:

Recently, yesterday, I got a new CEL code, P0134.
Sensor Circuit No Activity Detected (Bank I Sensor 1)

I suspected it might have been because of the O2 extensions cable I made myself. So I removed it and plug the primary o2 sensor directly to the engine harness.

Drove for about 50 kilometers, code did not come up. Will see to that.
CEL didn't appear right away either. Installed my new cat last Tuesday, so it took 5 days.

Thanks for helping me out.

ezone

Did this resolve the power loss/restriction too?

I was wondering if the original cat had broken its element and sent debris downstream to be trapped at a resonator or muffler. Chunks bouncing around in the exhaust pipes can certainly cause breathing problems, and sometimes even be intermittent as the chunks bounce around and change position.

Thaik

Not really.

Well, there's one thing I noticed is that restriction and engine load seems to be increasing as the engine warms up. I guess this is because catalytic converter work only when fully warmed?

I also noticed a smell coming from underneath the car right below me. There could be a leak which might explain the CEL code. I'll check that out too.

About the debris trapped downstream, I have replaced the resonator with an EX resonator, the muffler is the only part I re-used.

There's a lot of vibration coming from the engine and some from the cat itself, I can hear and feel it. Whenever I rev, not only there's the buzzing noise from the cat, but the cat seems to be vibrating too, like something is loose. The engine itself, there's vibration whenever I drive harder and rev it higher, I can feel it all around me, the seat, the steering wheel, the pedals.

The loss of power is not that noticeable, but there's definitely more noise and vibration coming from the engine than there was previously with the old cat/exhaust set up.

I'll check the leak and I'll keep you guys updated.

Thanks again.

Thaik

I also need to mention that I have noticed a noticeable increase in underhood temperature.

What used to be simply warm when touching such as the PS pump, the hood support rod, the front frame of the car to which the bumper clips onto, are now burning hot!

I do not believe it is because of the lack of heat shield because I used to be running without heat shield with the old header-cat and it didn't generate that much heat.

Or, could it be because I painted the EX header with high temperature black enamel paint made for stove to prevent corrosion and rust?

I heard because of the black paint emissivity and absorptivity properties that it could not only radiate more heat which is good for cooling but could also absorb more heat which is bad since the engine compartment has lots of it!?

Or could it be simply because there's restriction, therefore, the exhaust gas cannot be evacuated quickly enough and causes exhaust gas to be pushed back into the manifold from the cat?

I'm really puzzled here. I'm about to swap back to my old exhaust set up because I fear it will damage the engine (exhaust valve?) because of the excess heat and back pressure.

I didn't notice it that much, but now, accelerating is really a pain, engine load increases, sounds louder and I really have to push the pedal further down for it to accelerate quicker.

Who would have thought that I would actually prefer the old crappy leaky exhaust set up over the new one...

At the same time, I'll check the Magnaflow cat if there's anything stuck in it. It may be a pain to remove it though if it stuck far down against the catalytic converter itself. Could compressed air plugged into the secondary O2 sensor hole do the job or would it damage the cat?

I will also be able to confirm it is indeed the new converter that is causing all these issues and not my engine failing!

ezone

Exhaust can run upwards of 500-1000 degrees F, depending on loads and proximity to the engine.
Ever seen an exhaust manifold glowing? They can.
A cat pushes the temperatures even higher. You moved the cat downstream so that moved some of the heat.
The engine and radiator can always be 180 or higher at operating temp. The radiator dissipates that heat into everything else in the engine compartment due to air flow convection.

BUT a restricted exhaust and an overworked engine can run those temps high too.



Unbolt the pipe from the rear of the new cat. Put a sling around it hold it up so it can't drag the ground. Go drive the car long enough to see if full power is restored.
If you now have full power then the restriction must be in the sections you unbolted.

If it is still lacking power, unbolt and remove the new cat (and disconnect the rear O2 sensor from its connector). Drive the car again. Got full power now?

Thaik

Isn't this going to get freaking loud?

kinakoes2

Yes. Also be prepared for some mean backfire. But it is diagnostically sound.

So does the MF cat come as one piece like the stock dnpipe/cat? Because if so its prolly hard to see peanuts in the pipe at the cat ard that angle.

Thaik

I don't think I can do that where I live.
I'll probably annoy the neighbors and they'll call the cops and they'll probably give me a ticket.

Thaik

Aside from that, I've got some updates.

I've removed the EX exhaust system, and put back the old DX one with the cracked cat-header.

The clicking/buzzing noise disappeared but it retain every other symptoms such as change in engine noise whenever revving high, reduced power and throttle response. However, the drastic increase under hood temperature disappeared, probably because of the black paint on the EX header?

Before swapping the exhaust system back, I checked for leaks, there were none, and I also couldn't exactly pinpoint the specific location from where the buzzing/clicking noise was coming. It seems to come from between the back the engine and the converter, but I cannot be sure, noise and sound seems to be traveling along the under body and bouncing back at me from the engine. I even used a stethoscope still couldn't pinpoint its rightful location.

I know it doesn't come from the engine because when I swap to the old system, noise were gone.

I now suspect the primary O2 sensor since I did get a P0134 code.
Can the O2 sensor start to fail but in an intermittent way?
Because I cleared the code and it didn't come back. But, I noticed it appeared the next day after I've driven the engine hard the day before to test the new catalytic converter.

On the first days after the installation of the converter, the car ran really well, even better than before the new exhaust installation, but it is as I drove the car and drove harder that performance started to drop.

Engine getting old and failing? Or, coincidence: O2 sensor starting to fail at the same time as I swap exhaust?

ezone

Take it easy until you get away from your own neighborhood.

I run open pipes on my Hog this way. My neighbors still hate me anyway.
Possible....
Disconnect that sensor, that puts the computer in open loop and it uses a base fuel map instead of using feedback from a possibly faulty sensor.
Test drive and see how it runs.
Try this first?
I would still be doing what I said. Disconnect the rest of the exhaust and see if power returns. Be quick before the cops can get there.


Unless you have a way to connect a pressure gauge in the O2 sensor holes to actually measure backpressure. Disconnecting the pipe is way quicker.


Get under the car and bang on the exhaust pipes and mufflers listening for anything that sounds loose inside (there shouldn't be anything loose sounding or rattly inside the exhaust).
Rubber mallet, not a hammer.

Due to presence of heat shields on the original exhaust?

Thaik

Due to presence of heat shields on the original exhaust?

No, not even! I've driven the car with this cat-header without heat shield and it never generated that kind of temperature.

Disconnect that sensor, that puts the computer in open loop and it uses a base fuel map instead of using feedback from a possibly faulty sensor.
Test drive and see how it runs.
Try this first?

Are you sure this won't damage anything? Such as the O2 sensor itself and the catalytic converter?

Because after I installed the new excaust system, I forgot to plug in primary O2 sensor and I instantly got a P0135 (Oxygen O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1) and a P0420 (Catalyst System Efficiency Below Threshold (Bank 1). I let the engine idle for maybe 3-5 minutes before noticing the Check Engine Light.

Do you think that might have contributed to the O2 sensor failing (if it is, of course) and the reduced power?

Get under the car and bang on the exhaust pipes and mufflers listening for anything that sounds loose inside (there shouldn't be anything loose sounding or rattly inside the exhaust).
Rubber mallet, not a hammer.


I already tried holding each part in my hands and shaking them (after removing them of course) and I heard nothing. Even tried using a vacuum cleaner and using it to push air inside the pipes instead of sucking it, there didn't seem to be any restrictions.

I'm reluctant about removing part of the exhaust... Still prefer measuring the back pressure.

Anyway, I'll try unplugging the O2 sensor.

ezone

P0134 code is for no sensor activity.
Disconnecting the sensor for testing won't hurt it (it's already got a code).
Cat won't normally be damaged unless the engine runs super rich or has severe misfire.

If the sensor problem is somehow causing the computer to deliver inadequate fuel, disconnecting the sensor (remove that input to the computer) should restore basic preprogrammed fuel delivery by default (base fuel map).

-----


A vacuum cleaner can't move the cubic volume that an engine produces at wide open throttle and redline RPM. A restriction in the exhaust becomes more evident as the volume of exhaust being moved needs to increase.

What is that.....at wide open throttle and redline....about 630CFM through a 1.5 inch pipe? Now clog that pipe so its effective diameter is halved and see how it runs.

Picture trying to breathe through a coffee stir-straw. Now go jog around the block trying to breathe through the same straw.

HTH

kinakoes2

Reduce the radius of a pipe by half, and its flow resistance increases 16x.

Double the length of a pipe, and its resistance to flow doubles.

So reduction in cross section of a pipe is *far* more important than length -- even a little obstruction can double your flow resistance... and that's when you're cat's shiny clean and clear, never mind clogged with ash.

Thaik

I have disconnected the O2 sensor and there isn't much difference.

Apart from the fact that the engine rev slightly smoother, less vibration, the engine pretty much feels torque less. In other words, I do lose some power, but not that much.

Connecting the sensor back, the engine has a bit more vibration, but has more torque and power.

About the restriction in the exhaust, the reason why I'm skeptical about this is that why didn't it happen sooner, like before swapping the entire exhaust (except the muffler), it happens only after I install the new EX exhaust system, and it doesn't even happen right away, it happens like few days later as I drove the car.

Supposing there are some debris from the old cat that has been pushed further downstream towards the muffler, why didn't it clogged the muffler sooner but now? The muffler is the only part that I re-used.

I know many of you might be insisting that I should unbolt part of the exhaust and run it that way, but I just can't. I live in a neighborhood with lots of residences tightly placed closely to each other and not a lot of open spaces. I'll surely upset the whole neighborhood and make a fool of myself.

ezone

You can burble outside of your hood all calm and inconspicuous before you stomp on the gas pedal.



Take it out of your hood to the country, pull off the road, disconnect the exhaust. Give it hell until you have your answer. Reconnect and go home.


Leave the exhaust all connected as normal....Put a pressure gauge in place of an O2 sensor so you can get some backpressure readings as you drive.


Small chunks can bounce around in the pipes as you drive, then get lodged and clog at random times and conditions.
Stop the engine, the chunks fall down and open the clog.....until the next drive when it could happen all over again.
If you have ever seen the honeycomb type construction of a cat substrate, you would probably be better able to see how a broken chunk could allow flow if it lays one direction but block flow if it turns 90 degrees.




I'm only speculating about chunks of the old cat being the cause, since it seems likely.
There could be other issues that can cause excessive exhaust restriction too, such as an internally collapsed double wall pipe.

Thaik

Could there be anything else aside from exhaust restriction?

I cannot hear anything bouncing in the exhaust pipe.

The old cat-header doesn't seem to be that bad to the point it started falling apart and breaking down. I cannot hear anything moving inside it.

ezone

Sure.

But you seemed to indicate this all began with the exhaust changes, so....

kinakoes2

Still thinking it's a piece of something caught in the exhaust somewhere.

-- underhood heat
-- 'boxy' exhaust note
-- much less power esp at higher rpm

... all point to an exhaust restriction somewhere. Added to the fact that the new cat was buzzing/clicking at first, this seems to point to when it happened... if not the substrate, then from another piece of hardware (perhaps even a tool dropped in the wrong place).

Time to remove the entire exhaust, and do the tapping and bore-sighting (esp the new cat; light on cord down the elbow side -- make sure you can see light through all the holes. Shop-Vac on blow may also help find what part of the exhaust has the culprit.

Thaik

Now that I have swapped everything back in.

The extra under hood heat disappeared, but the restriction is still there, as I mentioned.

The muffler might be the culprit since it is the only common part in both exhaust set up.

I heard from outside my car being driven and I can hear something is restricting the exhaust somewhere that wasn't present before the EX exhaust installation.

But seriously, I'm still wondering how the hell something manage to get stuck in there, especially not a tool.

I also have to mention one other thing.
Even before doing the conversion, I started hearing noise from the engine/exhaust as is something was leaking. At first I thought that perhaps it was the cat-header simply leaking more and I thought: "well, I guess it's now or never to replace it".

But then, right after the replacement, the noise was still there, I was like "what the... I sure did check for any sort of exhaust leak and there was none..." Checked the header, the downpipe-cat, the resonator, the muffler, all the flanges, O2 sensors mounting holes. Nothing.

The noise seems to be coming from the front end, like a puffing noise. I can only hear from inside the car and it is more noticeable when the car is warm.
It is both present with the EX exhaust setup and the original DX setup.
Difficult to describe it. It's like a loose pipe with a small exhaust leak.
I hear it whenever it idles and when I engage the clutch at very low RPM, I hear some kind of resonance and reverberance.

I did heard gurgling and bubbling noise in the winter whenever I revved the engine, thought it was air in the cooling system, now it's gone in the summer, don't know if it is related though.

ezone

You know what you have to do.....

Thaik

Yup, thank you for your advice.
And sorry for talking too much.
I thought the additional info could be relevant for an experienced like you more than it is to me.

ezone

Pop just the muffler off and drive it?
Shouldn't be unbearably loud that way.



If the restriction is in the rear, and it creates enough backpressure under a load, it could cause the spring loaded joints in the front (IF equipped) to open up to let excess pressure out. I haven't actually seen this happen on Hondas, but I've seen it in the past on other brands.

Just a thought.


If you were close I could come by on the Hog (it's got open pipes and megaphone effect cans LOL) and escort you out of your hood with no exhaust, nobody would be able to tell your car is loud.

Thaik

By this do you mean the spring kit?
Because there's a spring kit connecting the exhaust manifold-cat to downpipe/resonator and another one bolting the latter to the muffler.
But that's probably not it.

What do you mean by Hog? Is that a Harley Davidson motorcycle?
Harley Owners Group, that's what I got on Google.

Also do you think it might be possible to see what's causing the restriction in the pipe by inserting snake camera like this one?


Because let's say that the muffler is the culprit, that doesn't change the fact that the Magnaflow cat I bought has a strange buzzing noise to it, I know it comes from it because I have removed it and hit it with a mallet and I hear that same buzzing noise.
But before sending it for a warranty claim, I want to make sure it is the cat itself and not something that fell off inside the downpipe and stuck against the honeycomb substrate.

Also, if I ever find something, how am I suppose to remove it?
Just to give you an image of the part:


Spraying high pressure water on the other side and hope that it will push out whatever debris there's in there upstream?
Or will that damage the cat? Because there's water coming out of the exhaust pipe from the chemical reaction in the cat...

Anyways, while it is not totally related, this is still about the exhaust conversion topic.

About popping the exhaust, yes, I'll probably do it, I have to find an empty spot in the countryside without too many residences and also a parking spot to be able to jack the car up safely and away from traffic.
So yes, I'll definitely do it.

kinakoes2

Yeah the angle in the downpipe being not removable from the cat, was what I was suspecting re: packing peanuts. The temps in the cat get extremely high... and whatever MF used to pack their product, if it gets past that 90 deg bend and to the cat (and you know how static electricity tends to make them stick all over things), it'll ash right on the substrate, possibly blocking some holes through the material. But yes, a light, even a LED keyring light you drop in and look through the substrate to see, will help ID what's up.

The only other variable is the muffler, and you'll test that off and on later.

--

BTW... the term 'hog' as pertaining to H-D motorcycles, came long before the Harley Owner's Group... but it was a natural acronym to use with such a huge club. H-D owners, esp the real bikers and not the Sunday-coffee-only, dealer-parts-counter-whoors, don't really appreciate a non-H-D-rider calling their ride a 'hog'. They tend to take the term as endearing only from chosen other riders... don't ask how I know that.

Thaik

Damn, hope that's not the case, and if it is, whose fault is it and how can I prove it's not mine? smh

Haha, thanks for clearing this up!