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2002 Sable...mass air sensor?

  #1  
Old 08-12-2009, 08:15 AM
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Default 2002 Sable...mass air sensor?

3.0 engine. In particularly hot weather (especially when ac is on) if car is turned off- it intermittently rough starts and bucks like hell when restarting.
Sometimes stalls out and takes 20 minutes b4 it will start....

battery tested like new, same with alternator. Could it be the mass air sensor?
I unhooked the wiring clip from it and due to extreme hunidity..it idles a little weird now and then- but essentially runs fine. (though I obviously get a Check Engine lite now). It only has done the bucking when the clip is connected.

Is it safe to continue running with the wiring disconnected?

AND

is there anything else it MIGHT be?

when it's running- the motor sounds very smooth and runs well.
however (i read in another post) about when gunning it while parked, I hear a little "woof" before the rpms pick up... (and no jokes about looking for a dog under the hood)...just wondering what that might be.

Thanks!
 
  #2  
Old 08-12-2009, 08:16 AM
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car has 88000 miles on it
 
  #3  
Old 08-12-2009, 12:21 PM
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it could be oxygen sensors, the mass airflow sensor. since you disconnected the mass airflow sensor and it runs ok, that could be the bad part. that's what tells the engine computer how much fuel to add to the mix (with the oxygen sensors used to fine tune it).

there could also be a restriction in the air filter box/hoses. but from what you are describing, it sounds like the airflow sensor you have disconnected needs to be replaced. wait for a confirmation from one of the other guys on this. I'm still learning about some of the top end stuff myself.
 
  #4  
Old 08-12-2009, 06:40 PM
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i would think a MAF sensor would throw a OBDII code. If they are anything like a GM the fuel pressure regulator could be bad and let fuel bleed out of the fuel ring when the engine has been shut off.
This condition can make it start hard hot (or cold) and run rough for a few seconds until the fuel ring is re-pressurized and bled off. Fuel pressure regulators seldom flag any code. Just a thought.
 
  #5  
Old 08-12-2009, 07:54 PM
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it depends on how they go bad. if they are just marginally bad and not totally shot, then they can cause issues because the computer thinks it's still getting a proper signal from it. They can also be bad by being rather dirty, but cleaning them is usually a difficult task that ends up breaking them if not done right (and I don't know the right way... I just replace them). The same can also be said about oxygen sensors. they will tend to make the engine flood if they get caked in carbon deposits but are still providing some marginal signal. Had that issue with an old pontiac I had. (I also need to check the sensors on my land yacht... but I'll probably wait until my car doesn't pass inspection or actually throws code on them.) It could also be a blown injector that leaks gas all the time into one cylinder. After a little bit it would run ok. I'm kinda doubtful about this one because it wouldn't be fixed by letting the engine cool for another 30 minutes unless the gas seeps into the oil (smell the oil dip stick and see if it smells like gas - good indicator for the broken injector). another issue could be the ignition module, a loose spark wire, fouled plugs, or a number of other things.
 
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