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2003 gmc envoy_sle_xl
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Discussion Starter · #1 ·
I have searched around a bit and have yet to come across a solution(s)....

We have an 03 Envoy XL 4.2...The idle has been rough so I did a basic tune up replacing all of the filters, fluids, and spark plugs. Still the rough idle persisted. The check engine light came on so I took it to the auto parts store to have the code read...something to do with a vacuum line the guy said and he cleared the code (I did NOT want him to clear the code). I have checked all of the vacuum lines I can find and can't find a vacuum line that is not connected.

So I broke down and took it to the stealership. They charged for a diagnostic and said they couldn't find anything wrong if there wasn't a check engine light. I thought....are these guys even mechanics????

So I took it to another dealership....they take a look and say it is my motor mount that is cracked causing the rough idle and that it may also be my catalytic converter. They wanted to charge me two legs and an arm to replace so I said no thanks, I’ll do it myself.

I had the motor mount replaced by a buddy with a shop and lift. We examined the old motor mount and COULD NOT find a crack or any defect with it.

So these supposed to be "mechanics" at the dealerships are just making stuff up because they don't know the vehicle and can't do anything without an engine problem code.

The check engine light has not come back on but the rough idle is still there.

Does anyone have any idea what else might be causing this? The dealer supposedly checked everything out and they say nothing is wrong...but it clearly is and they acknowledge the rough idle.

Is there a special vacuum line I am missing somewhere? What else could be causing this thing to run so rough? Any input or similar experience that was solved appreciated.
 

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2004 gmc
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26,181 Posts
By rough you mean a vibration around 10 Hz? Not a fluctuation that happens every few seconds?

For me it was the motor mounts. One huge clue was it behaved differently on cold mornings when the collapsed mount was stiffer. And the vibration went down or away witn I was in neutral, not drive, while stopped.

Other threads suggested, and I tried to do first, with a little change, was changing the camshaft position sensor and then the cam position actuator/solenoid. Some folks clean the screens on the solenoid, but I just swapped mine. There's a Dorman aftermarket part now that costs less then GM, who used to be the only source for the part.

Rereading your post - you only changed ONE motor mount? At least on a 2WD it's easier. My passenger side was far worse than the driver's side. Why didn't you change both?
 

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2003 gmc envoy_sle_xl
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Discussion Starter · #3 ·
Thanks for the replies. Yes I just replaced the right side motor mount that the dealer said was cracked. I saw no reason to replace both at this time as I feel like this thing is begining to siphon money from my account.

Someone mentioned cleaning the Throttle Body out. I will do so as well. Cleaning them is common procedure on my Jeep and I just replaced an Idle Air Control module on that to cure an idle issue. They do build up carbon pretty badly. Thing is, unless the throttle body is completely gunked up bad I don't see it causing as bad an idle as this is having. Maybe though, sometimes it's the small overlooked item. As well I don't know why that would throw an engine check code/light on the dash. I'll clean it anyway. Just put new shocks on as well btw. lol.

Envoy needs an accronym like Jeep (Just Empty Every Pocket)
 

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2004 chevy trailblazer_lt
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997 Posts
Envoy doesn't need an acronym because, unlike Jeeps, problem areas are fairly predictable and diagnosable across the platform. With the help of this forum, we can solve almost anything.

That being said, answer one question before we move on. Before the rough idle, had you recently changed or disconnected your battery or had to have a boost?
 

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2003 gmc envoy_sle_xl
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Discussion Starter · #5 · (Edited)
Envoy doesn't need an acronym because, unlike Jeeps, problem areas are fairly predictable and diagnosable across the platform. With the help of this forum, we can solve almost anything.

That being said, answer one question before we move on. Before the rough idle, had you recently changed or disconnected your battery or had to have a boost?
I disagree....Envoy should have an acronym...and unlike Jeeps their problems are not fairly predictable, in my case...

Never needed to boost the battery...

Turns out after taking it back to the dealership for another round of guessing and chewing into them they took some extra time to actually trace the issue with what come out to be somewhat of a vacuum leak as I had mentioned to them, the fuel tank has a vapor leak at one of the seams. Defective fuel tank. They have agreed to replace it and take care of all charges including labor and replacing the other motor mount free of charge.

Case closed.
 

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2003 gmc envoy_sle_xl
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Discussion Starter · #7 ·
lol - I'm just glad the issue(s) has been worked out. It has been going on for a little while. I think my boat may envy both vehicles as it gets all of the fun time.

Hope others can find the forum and its members helpful as well.
 
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