Mustang GT... Car running lean with unsteady idle - Ford Mustang Forum
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post #1 of 29 (permalink) Old 10-07-2007 Thread Starter
 
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Exclamation Mustang GT... Car running lean with unsteady idle

Ok, so i cleaned the MAF, TB, and swaped the TPS for a new one but the idle still isn't steady.
The check engine light just came back on tonight, and the funny thing is it's in the same town as it came on last time. Where i am now (the gf's parent's house) it's about 2500 feet, compared to sea level (my house). It's also about 20 deg cooler. I'm guessing that must have something to do with it. But learning from my last mistake (and a few smart forum members), i now keep my X-Cal II in my car, so i was able to extract a PO171 and PO174 OBD II code.

Does anyone know why it would be running lean? The only reason I can think of is the airflow may be restricted since i recharged my air filter. This is the second time i've recharged it (after I cleaned the MAF, TB, and changed the TPS), since the first time i over oiled it.

Thanks again everyone for the help!...

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post #2 of 29 (permalink) Old 10-07-2007
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You could have a plugged or failing fuel injector(s).


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post #3 of 29 (permalink) Old 10-07-2007
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What is recharging the air filter? Is that cleaning it?

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post #4 of 29 (permalink) Old 10-07-2007 Thread Starter
 
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Quote:
Originally Posted by bigwilly43729 View Post
What is recharging the air filter? Is that cleaning it?
yeah...clean, rinse, and re-oil.
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post #5 of 29 (permalink) Old 10-07-2007 Thread Starter
 
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You could have a plugged or failing fuel injector(s).
Is there a way to check and clean them, or do they need to be replaced?
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post #6 of 29 (permalink) Old 10-07-2007
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I have some guesses.

You have oiled your filter and now that oil has gotten on your MAF sensor. That can gunk it up, attract dirt, and affect performance of the sensor. Make sure your filter is not over oiled, or wet, and getting oil (or water or anything else) sucked upstream. Also clean your MAF again with brake cleaner and make sure it is COMPLETELY dry before reinstalling. And do this after you have verified your filter is not oiling/watering your intake air.

Also, check downstream of the MAF for ANY kind of air leaks in your intake. But I have a strong suspicion this is something to do with cleaning that filter.

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post #7 of 29 (permalink) Old 10-07-2007
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You could also have a fuel pressure issue (low fuel pump presure) or clogged fuel filter.

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post #8 of 29 (permalink) Old 10-07-2007
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well we know your running lean both banks... meaning it gotta be a common thing to both banks... either vacuum leak or your getting low fuel pressure bad fuel filter or pump going south but that is usually more noticeable with a load on or at high rpms. i would say look for a vacuum leak just a friendly advise...

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post #9 of 29 (permalink) Old 10-07-2007
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I wouldn't use brake clean to clean the MAF. There are MAF cleaners made for that. CRC is one.


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Quote:
Originally Posted by travelers View Post
I wouldn't use brake clean to clean the MAF. There are MAF cleaners made for that. CRC is one.
+1... Brake cleaner is a little harsh.

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post #11 of 29 (permalink) Old 10-07-2007 Thread Starter
 
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Quote:
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I wouldn't use brake clean to clean the MAF. There are MAF cleaners made for that. CRC is one.
I used CRC's specific products on both the MAF and TB. I was hoping that would fix the problem, but unsuccessful.
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Why did you change the TPS?


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Did you disconnect the battery when swapping the TPS? Did you use new fasteners and torque them to specs?

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i recommend you not to relly on the fact that you clean MAF (what ever you used) and air cleaner,cleaning the TP because those are just quick fixes....if that,,. you need to get to the source of the problem before you mess with any of that stuff because that may only make matters worse..... other think i can think of is maybe you contaminated your o2's depending how much you over oiled it??? it does take alot to contaminate o2's..
check to se maybe you left some vacuum line unplugged... i dont know???? huh?

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What are your mods? Assuming you have no more than the basic run of the mill CAI, catback exhaust, pullies, etc. why not put your stock air cleaner and tune back in and take it to the dealer? Anything which is emissions related is still under warranty. If it is throwing error codes it won't pass smog and Ford is liable.


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