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Discussion Starter #1
Here's the car:
2008 2.0L Focus Sedan PZEV
Trubendz 2.5" exhaust (high flow catalytic converter)
Fswerks CAI

Here are the syptoms:

Loud Intake:
Very loud noise coming from CAI. Definitely not the typical noisy CAI noise, I know what that sounds like. This literally sounds like my CAI has become my exhaust. When I rev the engine, it roars and pops and gurgles like my exhaust used to. Acellerating it is extremely loud. This isn't me being sensitive. I have a 69 Lemans with a 350 V8 and Magnaflow super 60 exhaust. i know what loud is. My CAI is snugly fit onto the TB. there are no leaks.
My MAF sensor also doesn't appear to be dirty, we're going to check to make sure that it is getting power right now. I'd also like to point out that even when we disconnected the MAF sensor, the engine ran the same. We even turned the car off, disconnected the MAF sensor and restarted again and it ran. Should it be able to do that? [8]

Quiet Exhaust:
My wonderful roaring Trubendz cat-back exhaust now whispers. I had someone rev the engine and stood back by the tip with my hand near it and the flow has been cut by some 60%, as well as the noise. There are no exhaust leaks, I checked the ENTIRE pipe for leaks, from manifold to tip, with the engine running even.

Power loss/hesitant engine:
I am experiencing a decent power loss of about 20%. as well as this the engine seems to have trouble maintaining power somtimes, where the RPMs will drop a few hundred, pick back up, drop and pick back up. This happens especially when I am accelerating at a constant rate.

Fuel Economy:
My MPG has dropped by a few points, to be sure.




So, there's my messed up situation! If you have ANY ideas, please tell me! This car is my sole method of transportation to work and school, and I dont really have the money for a mechanic, nor the time to wait.
 

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Discussion Starter #4

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I am thinking that you cat is clogged, or coming apart.
 

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That's a tough one. That's a lot of funky symptoms all mixed into one. Make sure fittings and connections are all snug. Did you try resetting the ECU?
 

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Discussion Starter #7
Disconnected the Exhaust at the flex pipe. The car ran the same and there was no change in noise. Even when revving, all the noise is coming from the intake. My car made essentially NO exhaust noise running with just the manifold and flex pipe. WTF?!

Also, I even was able to disconnect the MAF sensor and the car ran. So, with the MAF sensor and cat disconnected, my car still ran in this weird state.

I am lost on this one. My catalytic converter is definitely not clogged. o_O
 

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Are you popping a check engine light? You should be if its running that jacked up. I would look into maybe conducting an inspection of your head to make sure everything is working right in there. I had all the similar symptoms except for all the noise coming from the intake. Turned out to be a blown piston ring but it sounds like your head isnt realeassing exhaust the way it should be.
 

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Discussion Starter #9
Are you popping a check engine light? You should be if its running that jacked up. I would look into maybe conducting an inspection of your head to make sure everything is working right in there. I had all the similar symptoms except for all the noise coming from the intake. Turned out to be a blown piston ring but it sounds like your head isnt realeassing exhaust the way it should be.
No CEL. Even plugged in the reader and no code came up. Our local NAPA guy was stumped when we took it to him. Gonna go see a mechanic tomorrow.
 

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Haha, yeah thats crazy man. Usually a rough running motor will throw some kind of CEL even if its a small code. Mechanic is your best bet. Just dont let em rip you in half with their crazy prices and what not. Try googleing the symptoms and maybe that will give you a better insight of what the problem might be. Im curious myself so i think i will go do that right now.
 

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You did not say if how recently you had installed all this hdwre. So assuming then that it's all new, And >> "I'd also like to point out that even when we disconnected the MAF sensor, the engine ran the same. We even turned the car off, disconnected the MAF sensor and restarted again and it ran. Should it be able to do that?"
I think you have ID'd the problem area. I suspect a broken wire or connector, or possible the MAF is in backwards. But something to do with that area. My 2 cents anyway.
 

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zetec 2 duratec swap
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The car doesn't need the maf to run. It will crank over and rev all of that but it won't be smooth and will hesitate to respond to your throttle input. It sounds to me like you might have an exhaust leak at the manifold.
 

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None of that explains the quiet exhaust and loud intake.
 

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Busy Monkey
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You said you've already disconnected your exhaust at the flex pipe and it was still quiet, so it's not that, so I'm betting it's Ford's brilliant mani-cat. If you unbolt your exhaust manifold from the block and fire it up for a second you'll be able to tell immediately: it'll be loud as hell. I'm betting that the cat that's built into your POS stock header is clogged.


*DISCLAIMER*
My advise is only what I would do in your situation.
Always take proper safety precautions. I.E. Make sure nothing is hanging in the path of exhaust exits, always have a fire extinguisher handy, and use eye and ear protection.
Neither myself nor FocusFanatics.com will be held responsible if you mess up and injure yourself or start your car on fire.
 

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Discussion Starter #15
Thanks for the replies, guys!

The hardware on the car is coming up on about a year now. Sort of new but well past the break-in period.

I can say with absolute certainty I have no exhaust leaks whatsoever.

As for the MAf sensor, we checked it. It's facing the right direction, no debris in it, the wires are all nice and healthy.

@MisterJohnson
That, sir, is an interesting idea. I hadn't thought of the second cat. I'm taking the car into my mechanic next week. I may or may not attempt the partial manifold removal myself haha, but I'll throw that idea to him.
Do you think a clogged mani-cat could be sending noise out of the intake, though?

EDIT:
Also, if it turns out to be the mani-cat that is the problem, I think I'd like to replace it with a header. So 3-1/2 questions there:
1. Do any aftermarket headers have catalytic converters in them? (Probably a stupid question)
2. CA folks, do you think I could pass smog with the mani-cat removed, so long as the secondary cat is still in place?
3. Would the header be worth the money if I still have a high-flow secondary cat? Or would it be mostly noise with marginal flow increase?
 

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Again, my 2 cents.
In reverse >
Question 3: No. or rather it would not for me. Lets say an open header would get you 10hp (we shall ignore the RPM issue ). If you 'plug' it with a cat, you loose 7hp. Assume the header costs $300. Is $100 per hp worth it? (You provide your own answer here).
Question 2: Prob not. Pesky technicality that you cannot remove emissions equipment. That's a fed law and applies everywhere where they actually check. Some places don't though so.....
Question 1: No. Reason is explained in question 3.

My Question > Did you buy this car new? I mean, the only thing that can plug a converter is if you run leaded fuel (or some additive) through it. It is not old enough to have severe carbon issues (assuming normal driving here). Just curious. Luck with it!
 

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Again, my 2 cents.
In reverse >
Question 3: No. or rather it would not for me. Lets say an open header would get you 10hp (we shall ignore the RPM issue ). If you 'plug' it with a cat, you loose 7hp. Assume the header costs $300. Is $100 per hp worth it? (You provide your own answer here).
Question 2: Prob not. Pesky technicality that you cannot remove emissions equipment. That's a fed law and applies everywhere where they actually check. Some places don't though so.....
Question 1: No. Reason is explained in question 3.

My Question > Did you buy this car new? I mean, the only thing that can plug a converter is if you run leaded fuel (or some additive) through it. It is not old enough to have severe carbon issues (assuming normal driving here). Just curious. Luck with it!
 

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If it's your cat it should be still under warranty.
 

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If it's your cat it should be still under warranty.
That really depends on how it got plugged (if that is the real problem). If leaded gas or additive was introduced, then there is no warranty.
 
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