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Old 11-22-2009, 04:59 PM   #1
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Car stalling when idling, AOS or Vacuumn Leak?

Recently my car has been stalling when it idles (in neutral or when the clutch pedal is pressed), I got codes for MAF and Oxygen Sensors so I replaced the Oxygen Sensors and cleaned the MAF with a cleaner from the auto store.

The car runs much more smoothly now, definite increase in power and the idle is much smoother WHEN IT IDLES. The problem is, half the time when I let it idle at a stoplight it will stall, but it starts again immediately. I noticed one time I was running the AC on idle, but then felt cold so I turned it off. Upon turning the AC off it did stall instantly, but again started immediately.

Could this be a vacuum leak? AOS fault? Maybe the MAF needs to be replaced?

If it is a Vacuum leak or AOS, are these easy DIY fixes or should I send it off to a mechanic? I'm still quite a novice when it comes to mechanics but I do know my way around.
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Old 11-22-2009, 08:08 PM   #2
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my 98 was running real bad check engine light was on also real sluggish and boggy ,and I tried cleaning the maf with mas air cleaner, it did not work ,just a waste of time ,so I replaced it cost about $200 shipped to my door 20 min to install, fixed the problem it runs a lot better ,I do not think cleaning them works ,
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Old 11-22-2009, 08:36 PM   #3
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Quote:
Originally Posted by rd400rz
my 98 was running real bad check engine light was on also real sluggish and boggy ,and I tried cleaning the maf with mas air cleaner, it did not work ,just a waste of time ,so I replaced it cost about $200 shipped to my door 20 min to install, fixed the problem it runs a lot better ,I do not think cleaning them works ,
I've heard both sides of the argument, but I want to be sure it's not a vacuum leak or AOS problem before dishing out 200 dollars to replace a MAF that might still be working.
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Old 11-22-2009, 10:59 PM   #4
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Saw another post recently about testing to determine whether the AOS is bad or going bad. With the car running remove the oil filler cap. If it's tough to remove, like there's pressure in the system keeping it on (you'll hear a swoosh or sucking sound when removing it), then it's likely the AOS. If you haven't see any of the infamous AOS tail pipe white smoke clouds, that's probably not the problem. Don't think the AOS causes your symptoms. A bad MAF sounds more likely.

I believe one way you can test the MAF is to try running the car with it unplugged. If it runs better, the MAF is likely shot. Someone else more knowledgeable about this will likely chime in. Lots of MAF posts on this forum. Have you read them all?

If you need to buy an MAF stay away from eBay. I've heard ********************************az has got just about the best price and, unlike eBay, you'll get the correct part.

You didn't mention whether you're still getting codes after the oxygen sensor replacement.

How many miles on your car?
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Old 11-23-2009, 12:11 AM   #5
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If you got a maf code ,and you did not replace it ,thats prollay what it is ,cleaning them normally does not work ,my 1998 has had two mafs and it has 88 k on it
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Old 11-23-2009, 07:40 AM   #6
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Cleaning the MAF is a waste. www.************************************************************ best place around.
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Old 11-23-2009, 09:03 AM   #7
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Quote:
Originally Posted by gschotland
Saw another post recently about testing to determine whether the AOS is bad or going bad. With the car running remove the oil filler cap. If it's tough to remove, like there's pressure in the system keeping it on (you'll hear a swoosh or sucking sound when removing it),
this is what my neighbors car did just this weekend - heavy smoke, and the cap took two hands to remove. I think I heard a whirrrrrrrrr sound coming from the AOS...but I'm not positive.

Keep us updates!
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Old 11-23-2009, 10:19 AM   #8
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You can use an (unlit) propane torch to help diagnose vacuum leaks, as the engine will increase RPM when you wave it near a leaking hose.

-james
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