MAF or intake vaccum leak?

Tiny
PITCHERFAN19
  • MEMBER
  • CHRYSLER
My car died on me last week and the dealer said it needed a tune up. They replaced plugs, ignition wires, distributor cap, rotor, and replaced bad intake gaskets(upper and lower). 30 miles later my car has similar sypmtoms but not as severe. It idles rough around 500 rpm and doesn't quite have the power it should, it seems sluggish. The service engine light is on and shows P0174, lean in bank 2. My mechanic diagnosed a bad MAF or an intake vaccum leak(possibly bad gaskets?). He was not defintive though. It seems strange but the car runs normal when the cooling fans turn on or the MAF is unplugged. The answer seems simple(change the MAF), but I just want another thought.
Friday, February 10th, 2006 AT 8:38 PM

5 Replies

Tiny
PEPPERMRJ
  • MECHANIC
  • 1,158 POSTS
A make, model, year, and mileage are a definite help.

Being that the intake manifold gaskets were just replaced I would recommend the following.

In the vast majority of cases, simply cleaning the MAF sensor does the trick. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
Inspect all vacuum and PCV hoses, replace if necessary
Check for a dirty fuel filter and proper fuel pressure

Good luck and let us know.
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Sunday, February 12th, 2006 AT 11:16 AM
Tiny
PITCHERFAN19
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Sorry about that. Its an 02 dodge stratus r/t, 5 speed, 58k miles. The fuel pressure is good, the injectors are good, the filter is in the tank. Thanks for the advice, i'll let you know!
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Sunday, February 12th, 2006 AT 11:55 AM
Tiny
PITCHERFAN19
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Codes today were P0174(lean bank 2) and a new code of P0171(lean bank 1). Ok so I replaced the MAF sensor and cleared the codes. About 15 miles later the service engine soon light pops back on. I assume the same 2 codes. The engine still idles very rough. It's like it wants to die around 500 rpms and then catches itself and shoots the rpms back up. Now im resorting to using fuel additives(heet) in case maybe the gas is bad, and it has been suggested to me to use an oil additive/detergent(CD2). I doubt this will really help but it can't hurt. BTW, this is a 3.0 V6 Mitsubishi engine, a real pain in the butt to diagnose from what I am told.
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Wednesday, February 15th, 2006 AT 5:48 PM
Tiny
PEPPERMRJ
  • MECHANIC
  • 1,158 POSTS
Double check the MAF installation and connections.
Lean means that unmeterd air is getting into the system. Check all your vacuum lines, especially the PVC and brake booster lines.

It is possible to still have a bad MAF or an intake leak around the manifold.

Take a look around and see if some other wires or hoses have come off or rubbed thru. With all the work that's been done underneath the hood it is worht checking.

Good luck and let us know.
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Wednesday, February 15th, 2006 AT 5:59 PM
Tiny
PITCHERFAN19
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So the codes are the same, but I found it odd that they both were thrown twice in 24 hours. P0174,171,171,174(in that order). Is that normal? Also im still confused as to why the cooling fans starting immediately smooth the idle out.
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Thursday, February 16th, 2006 AT 8:33 PM

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