2006 Jeep Grand Cherokee engine noises

Tiny
KEN
  • MEMBER
  • 2006 JEEP CHEROKEE
I have a 2006 Jeep Grand Cherokee with 22,700 miles. I started getting an exhaust leak at about 13,000 and the dealer finally (after 4 or 5 visits) discovered a leaking exhaust manifold gasket and replaced both gaskets. This eliminated the leak. Since then, I've installed a Flowmaster muffler and a K&N 63 series Air Charger air intake system. I'm getting another noise or collection of noises that sound similar to an exhaust leak. Its not present at idle or while reving while parked. I get the noise in all gears, but is most noticable under load/ acceleration in 4-5th gears. I went back to the shop that installed my muffler and they couldn't find any exhaust leak (using a stethoescope). I've read that installing a cold air intake such as the K&N will increase noise from the EGR valve. I've thought about re-installing the factory intake assembly to see if this is the cause, but haven't yet. I've also thought it might be valve or lifter clatter and tried to quiet this with Valvoline SynPower Oil Treatment. Can you offer any suggestions or other potential causes?
Sunday, April 8th, 2007 AT 11:43 PM

4 Replies

Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
With computer controlled engines, unless you flash the PCM all these aftermarket changes don't work! Different air intake setups are useless!
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Tuesday, April 17th, 2007 AT 4:32 AM
Tiny
KEN
  • MEMBER
  • 3 POSTS
Why would I need to flash the PCM? And what do you mean by "don't work". By disconnecting the negative battery cable for 3hours+ while installing the air intake, this should reset the PCM so that it had to re-map. I think it works fine.

And what do you mean by "different air intake setups are useless"? Could you be more specific.
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Tuesday, April 17th, 2007 AT 10:20 AM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
The mass air flow sensor meters the amount of air entering the system. More air means either confusion to the pcm or it's using the same amount!
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Tuesday, April 17th, 2007 AT 10:35 AM
Tiny
KEN
  • MEMBER
  • 3 POSTS
Sorry I didn't add this to my initial question, but I've got the 4.7L V8, which does not have a MAF. I has only an air temperature sensor in the air tract. Technically, with a cold air intake, the temp sensor should read colder air will cause the pcm to map the cooler air as denser and thus add fuel to maintain optimal air/fuel mixture. More air/fuel to burn equates to more power, as long as it burns efficiently. The same should be true of a MAF which measures air density - more, cooler air would cause the pcm to add more fuel to the mixture.

Anyway, I found my exhaust leak this last weekend coming from the ball joint flange between the cats and the muffler. Just need to get that fixed.
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Tuesday, April 17th, 2007 AT 10:46 AM

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