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Exhaust

Tiny
TURFDOG
  • MEMBER
  • 2004 HYUNDAI SANTA FE
  • 2.7L
  • V6
  • 4WD
  • AUTOMATIC
  • 180,000 MILES
Started up my car drove to work no problem. Leaving work I hear a sound like an exhaust leak I know it’s there it’s been there for a while but I can see the exhaust leaking from under the middle of the car. But now when I accelerate just slightly step on the pedal it runs rough and a lot of exhaust noise. I get underneath the car I checked everywhere in the front by the headers sounds OK there’s a strange exhaust sound coming from the catalytic converter but I feel no leak. The only leak I feel is after the resonator from the resonator connection to the secondary pipe to the muffler. I can understand if there’s an exhaust leak in front of the cat That would make the engine run rough because there’s no back pressure but I don’t feel or hear any exhaust in that area leaking. Can my cat go bad and not leak?
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Tuesday, January 21st, 2020 AT 1:01 PM

10 Replies

Tiny
MOTOR MASTER
  • MECHANIC
  • 279 POSTS
Hello my name is Dave.

Yes your converter can go bad without leaking, actually this is much more common than one going bad and leaking. Is your check engine light on? I would definitely expect it to be on, if it's not I would check and make sure the bulb in the check engine light is functioning by turning the key to run without starting the engine, the light should come on and stay on when you do this.
Either way I would start by checking for codes.

here is a link to our tutorial on how to retrieve the codes:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

As a rule if your converter is getting restricted you will get a code for running rich and/or a code for the oxygen sensor.
If you can check for codes and get back to us with the results we will be glad to help you make sure you make the proper repair.

Hope to hear back from you soon and thank you for using 2CarPros!
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Wednesday, January 22nd, 2020 AT 4:08 AM
Tiny
TURFDOG
  • MEMBER
  • 63 POSTS
Okay, so I took it to my mechanic and the leak was coming from the engine pipe like the header pipe so we changed from the catalytic converter back everything. But now I have a misfire in the number five cylinder. Can the exhaust leak affect the plug on that cylinder? I just changed the ignition modular wires and plugs about six years ago. So I’m a little concerned. I don’t see the ignition modular going that quickly. On top of that the number five cylinder is under the intake manifold. Any suggestions?
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Friday, January 24th, 2020 AT 11:40 AM
Tiny
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The leak itself will not cause an issue but if this is before the o2 sensors then it can effect the air/fuel mixture. Basically the PCM thinks the exhaust has more oxygen in it then it should so it richens up the fuel mixture. However, it doesn't enrich just one cylinder. It will effect all cylinders.

If you have changed the plugs in 6 years then we should go ahead and do that and see what the plugs look like. I suspect they are going to be fouled and if they are, maybe number 5 was just further gone then the others and replacing them will correct it.

I understand it is under the intake but there is no easy way to check it. If you want further info, you can monitor the o2 sensor data and see what it is saying. I suspect you will see a negative number which means it has less oxygen due to having more fuel in it. This would show the plug is not firing.

Hope this helps. If it doesn't then I would go ahead and get a new post started because we need to keep it one topic per post. Thanks

https://www.2carpros.com/questions/new
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Monday, January 27th, 2020 AT 5:00 PM
Tiny
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  • MEMBER
  • 63 POSTS
So I tried to change the ignition module like I did last time it didn’t help. The mechanic said that number five cylinder was misfiring so I switched from number five to number three the plugs. But I haven’t had a chance to have the code checked. So I’m just going to change one plug because that’s all I can afford at the time, LOL. I will change the one plug and see if it clears it up. I ordered a whole set but it hasn’t come in yet. After that I was thinking of changing the wires and if that doesn’t work then it’s back to the mechanic.
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Wednesday, January 29th, 2020 AT 11:16 AM
Tiny
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  • 63 POSTS
By the way I checked the plug in number five cylinder and it wasn’t fouled at all.
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Wednesday, January 29th, 2020 AT 12:01 PM
Tiny
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  • 18,907 POSTS
Thanks for the update. Clearly if the misfire moved to number 3 then that was the issue. If not, it could still be the injector or even a compression issue. However, I would not think it is a compression issue but we can't rule it out until we check it.

https://www.2carpros.com/articles/how-to-test-engine-compression
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Wednesday, January 29th, 2020 AT 5:40 PM
Tiny
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I still have a misfire but no check engine light comes on. And you can feel it when you slowly accelerate but, no check engine light. So change the spark plugs hoping that maybe it was one plug bad. No good. I’ll try to have the compression texted this week. I was just going to change wires Just for shits and giggles I already change the ignition modular. Unfortunately it’s a cheap one $50.00. There is a button on the right side of the engine cowling like a reset and I can’t remember what it’s for with somebody pointed it out to me once before. I pushed it and it clicked so I don’t know what that’s for. LOL right now I have the battery disconnected to see if I can reset the computer and go from there. It’s all I can think of now.
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Saturday, February 1st, 2020 AT 11:32 AM
Tiny
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Yeah. I think the compression needs to be the next thing because without a good base engine operation all else doesn't matter. So if nothing else, it will just confirm it is sound. Thanks
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Saturday, February 1st, 2020 AT 7:07 PM
Tiny
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  • MEMBER
  • 63 POSTS
So I change the wires I found a blown wire and the number five cylinder. The only problem I have is starting it it seems the check engine light came on the last time I had problems and it hasn’t gone off. So now when I started it stalls out and I rev it up until it hits an idle and it stays there. Not a big deal runs nice and smooth as soon as it catches the idle. But now I got to figure out what the problem is at starting. Any ideas? The codes that came up were misfire number five cylinder and crankshaft positioning sensor. But after I had it checked I started it and the left and the crankshaft sensor work fine. When that sensor goes bad the car only revs up to 3,000 RPM's the drives fine but won’t go any higher than 3,000. That happened on the way to the auto parts store. He checked it I turn the car off started it and it went away. Go figure. Maybe I just need to get the codes cleared?
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Monday, February 10th, 2020 AT 10:40 AM
Tiny
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  • MECHANIC
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So we need to start with what the codes are currently and then a clear description of what it is doing now.

Unfortunately, we need to get a new post stated with that info. We need to keep each thread to one issue. Others will not be able to find the solution to this starting/idling issue on a topic of exhaust.

https://www.2carpros.com/questions/new
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Monday, February 10th, 2020 AT 7:28 PM

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