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So I /think/ I have a vacuum leak...


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MollygizerBunny
Novice

Feb 3, 2013, 11:26 AM

Post #1 of 15 (1610 views)
post icon So I /think/ I have a vacuum leak... Sign In

Hey, all! I have a 2005 Pontiac Vibe (named Critter) with an automatic transmission that has been giving me some issues lately, and I'd love some thoughts.

Early December – While driving on the interstate on a long road trip to New Hampshire, check engine light comes on suddenly and the car begins to shudder. We take the car to a nearby truck stop, who tells us we have a misfire in the 3rd cylinder. He replaces the cylinder coil, the check engine light goes off, and we go on our way.

2nd week of January – Check engine light comes on with no symptoms. Take to an Advanced Auto Parts, they say it’s a code 420 / O2 Sensor. The guy says it isn’t urgent, and asks if we want to “clear” the code, so we do.

3rd week of January – Temps drop into the teens. The car begins to idle roughly when first turned on, whether or not car “warms up” in park. Check Engine light comes back on. Feels like the car is jerking when at a stop sign or red light. RPM gauge bounces downward each time the bump is felt, and the lights appear to dim slightly. However, the problem goes away entirely after 10-15 minutes of actual driving, once the heat gauge rises to 1/3.

Current – The check engine light is now solid sometimes, sometimes flashing. Took to Auto Zone today, where they tell us it’s a P303 – same code as in December, I would assume.

From the advice of 2 mechanic friends back in Tennessee, I think it’s a carburetor vacuum leak. It would account for both sensors coming on one after another. I don’t know if the issue in December is related, but it is too coincidental that it’s the same part. I’ve never had an issue my boyfriend couldn’t fix or that I couldn’t put off until I go to Tennessee 3x a year, but this seems a bit more urgent, so I want to know thoughts so I can seem smart when I go into an unknown shop a friend recommended. :D


Hammer Time
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Feb 3, 2013, 11:36 AM

Post #2 of 15 (1588 views)
Re: So I /think/ I have a vacuum leak... Sign In


Quote
From the advice of 2 mechanic friends back in Tennessee, I think it’s a carburetor vacuum leak. It would account for both sensors coming on one after another


Those guys need to stick with whatever they do for a living because it's not auto diagnostics. You haven't mentioned anything that would indicate a vacuum leak. Besides, your car doesn't even have a carburetor.

There are many things that can cause a misfire and the coil is only one of them. You never mention how many miles are on the car or what maintanence has been done in the past.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Feb 3, 2013, 11:37 AM)


MollygizerBunny
Novice

Feb 3, 2013, 11:44 AM

Post #3 of 15 (1577 views)
Re: So I /think/ I have a vacuum leak... Sign In

Car has 102K on it. I only bought it last spring from an older couple, so I don't know the history. I added the carburetor part... they said a leak in a vacuum hose. I tried to sound smart based on what I've read online. I failed.


(This post was edited by MollygizerBunny on Feb 3, 2013, 11:45 AM)


Hammer Time
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Feb 3, 2013, 11:46 AM

Post #4 of 15 (1570 views)
Re: So I /think/ I have a vacuum leak... Sign In

Have the spark plugs been replaced yet? If not, it's time. Make sure you are using Delco brand in that car.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



MollygizerBunny
Novice

Feb 3, 2013, 11:52 AM

Post #5 of 15 (1561 views)
Re: So I /think/ I have a vacuum leak... Sign In

I was under the impression that the cylinder coil is instead of spark plugs in new cars? Sooo... no.

I feel very dumb right now. I mean, I expected it, but dumb.


Hammer Time
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Feb 3, 2013, 11:54 AM

Post #6 of 15 (1554 views)
Re: So I /think/ I have a vacuum leak... Sign In

The ignition coil is the part that fires the spark plug. The difference now is that many cars have a separate coil for each cyinder instead of one that fires all of the plugs.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



MollygizerBunny
Novice

Feb 3, 2013, 12:05 PM

Post #7 of 15 (1535 views)
Re: So I /think/ I have a vacuum leak... Sign In

Ohhhh. That makes sense. I think.

So it could just be the spark plugs? Does that mean the O2 sensor is a separate issue that just coincidentally coincided?


Hammer Time
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Feb 3, 2013, 12:08 PM

Post #8 of 15 (1530 views)
Re: So I /think/ I have a vacuum leak... Sign In

Don't listen to those fools at the parts store. They are sales clerks pretending to be mechanics.
P0420 means low efficiency of the catalytic Converter and you will likely eventually have to replace it.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Sidom
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Feb 3, 2013, 12:27 PM

Post #9 of 15 (1524 views)
Re: So I /think/ I have a vacuum leak... Sign In

As Desi mentioned, the converter may need to be replaced but converters don't usaully go bad by themselves.....Most of the time there is a drivability problem that takes them out (a problem that makes it run bad)...

Sounds like you got something going on with the #3 cyl so you probably want to get a handle on that 1st before addressing the P0420..

Since it doesn't do it all the times, this can make it a little tougher to track down, but not impossible......


On a side note....Personally I've found that cars don't like it when they are named "critter".....you may try to pick a new name & see if that helps.....Wink


MollygizerBunny
Novice

Feb 3, 2013, 1:46 PM

Post #10 of 15 (1514 views)
Re: So I /think/ I have a vacuum leak... Sign In

But... but... it looks like a Critter!

As far as the P0420, is that something that, as long as I have a valid emissions sticker and I don't smell rotten eggs, I can put off until the summer? My dad's friend back in Tennessee will do it for parts cost. :P


Sidom
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Feb 3, 2013, 1:57 PM

Post #11 of 15 (1508 views)
Re: So I /think/ I have a vacuum leak... Sign In

When converters 1st start to fail & set the 420....It is more of an emission thing...So as long as you don't have to go thru smog then is can go on the backburner...

On the other end.....They can get plugged up enough to where it will effect how the engine runs and if it gets fully plugged the engine won't run....

If you are getting that "rotten egg" smell, that would indicate a pretty bad miss....So at a minimum you may want to get a handle on the running problem, before it creates someother ones....

Just an FYI....If the check engine light is on & starts flashing.....That means that misfire has got bad enough where it is doing serious damage to the converter......Flashing SESs are bad.....

Hopefully you can get back to TN soon and get this fixed up


MollygizerBunny
Novice

Feb 3, 2013, 2:02 PM

Post #12 of 15 (1501 views)
Re: So I /think/ I have a vacuum leak... Sign In

Another thought... even though the Auto Zone "reset" the 0420 a few weeks ago... shouldn't it have shown up today when they plugged in the little computer? 0420 was gone, but the 303 printed out.

And yeah... the flashing just started yesterday. Mostly when I was accelerating over the Williamsburg Bridge. I'm going to take it to a shop a local friend recommended on Tuesday to have the 303 diagnosed... just seeing if I can put off the cat since it would cost fifteen arms and legs that I don't have at ALL. Tongue


Sidom
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Feb 3, 2013, 2:26 PM

Post #13 of 15 (1497 views)
Re: So I /think/ I have a vacuum leak... Sign In

Every code the comp sets is associated with a certain "moniter"....A moniter has to run & complete before it will set codes for that system....Some moniters take longer to run & complete after the codes have been cleared......The misfire moniter usually sets right away (Fords are a different story), the cat moniter requires the cat to reach certain temps & the vehicle to reach certain speeds before it will run & complete........

Rest assured......You have a P0420 lurking in the shadows just waiting to set.....


Cats are THAT expensive!.....Most just take the shirt off your back & a pt of blood......


Hammer Time
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Feb 3, 2013, 2:57 PM

Post #14 of 15 (1487 views)
Re: So I /think/ I have a vacuum leak... Sign In

A Converter is the one thing that you don't want to attempt at home. Most require custom cutting and welding and a custom exhaust shop will usually do the whole job cheaper than you can even buy the parts but as Sidom said, fix the engine problem first or you will just ruin another cat.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



MollygizerBunny
Novice

Feb 3, 2013, 3:11 PM

Post #15 of 15 (1479 views)
Re: So I /think/ I have a vacuum leak... Sign In

Got it. Thanks, everyone. Smile






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