- #6 of 25
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Re: Spark Plug Replacement [nosirrahg]
by bena8837
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Aug 31, 2007 (7:53 pm)
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Replying to: nosirrahg (Aug 19, 2007 11:21 am)
Hello again, hate to bother you! I ended up having someone replace the 3 rear plugs on my car and have started having a different problem. I don't believe it started to do it right away but it has started making a bumping noise when it's started engine and when it's turned off. I got under the car to see what it was and it appears to be the exhaust system shaking when the engine is started and turned off. Do you think it is associated with the work that was done, and if so, what do you think might be the problem? Any help is greatly appriciated!
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- #7 of 25
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Re: Spark Plug Replacement [bena8837]
by nosirrahg
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Aug 31, 2007 (8:04 pm)
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Replying to: bena8837 (Aug 31, 2007 7:53 pm)
Hard to say...I've had a problem ever since I had mine replaced with the engine missing when it's lugged (going slowly up a hill with the AC on, just before it downshifts it will somewhat violently miss and jerk). I replaced my plug wires but that didn't help. From what I can tell my problem is with the plugs themselves (supposed fuel-saving "halo" design), and I plan to replace them in the near future.
The only problem I've seen mentioned that's exhaust-related has been with clogged catalytic converters, but that usually appears as a lack of power over speeds of around 45 MPH. Seems like there may be a wiring harness on the backside of the engine that's associated with the oxygen sensor or something (I remember reading somewhere where somebody said they removed this to help access the plugs, but I don't remember specifics and didn't try this on my car)...could be your mechanic moved/unplugged something like that to gain access and maybe didn't connect everything.
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- #8 of 25
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Re: Spark Plug Replacement [nosirrahg]
by bena8837
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Sep 01, 2007 (4:41 am)
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Replying to: nosirrahg (Aug 31, 2007 8:04 pm)
Thanks for the quick response. I replaced mine with original plugs. I have also noticed that the 2 front brackets seem to be looses compared to the way they were before,could this be allowing the engine some movement? Would the engine go back to it's original position without any problems? Would the rotation of the engine have an impact on the exhaust, or is it the engine that is misbehaving? I would think that if something is disconnected I would get some kind of message? Thanks alot!
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- #9 of 25
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Re: Spark Plug Replacement [bena8837]
by nosirrahg
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Sep 01, 2007 (9:06 am)
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Replying to: bena8837 (Sep 01, 2007 4:41 am)
If the front brackets are connected to the engine and to the frame in the front of the car, then that shouldn't be an issue. From what I remember it'd be difficult to put them back in any way except the correct position, so unless they aren't bolted down on both ends I doubt that's a problem. It might be possible to run the bolts on the frame further towards the front of the car then they're supposed to go, but there's sort of a rubber/foam-like material that the bolts to through up there that makes it pretty obvious where the mounting should bolt go.
As far as going back into position you have to pull the engine forward and strap it down to hold it there while you work on it, otherwise it basically stays in it's upright spot - at least when the engine isn't running (not sure how it would react if you started the engine when those upper mounts weren't connected). I suppose it's possible that in tilting the engine something could have come loose or bent exhaust-wise, but I'd think it would be an issue at other times beyond just starting/killing the engine.
FWIW my engine missing problem has NEVER prompted any type of "service engine soon" or similar message on my car, which puzzles me actually.
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- #10 of 25
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Re: Spark Plug Replacement [nosirrahg]
by bena8837
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Sep 02, 2007 (5:09 am)
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Replying to: nosirrahg (Sep 01, 2007 9:06 am)
Went back and checked everything that had been done as if going to replace rear plugs and the very 1st thing I checked was the brackets because I remembered when I wrote that I told you the brakets were not tight as before. Well, one of them was not tightened, the bolt was there hand tight and I am suprised it didn't fall off. I tighted it and Thank God, that fixed it. Many, many thanks for your imput, appreciated!
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- #11 of 25
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Re: Spark Plug Replacement [bena8837]
by nosirrahg
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Sep 02, 2007 (5:19 am)
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Replying to: bena8837 (Sep 02, 2007 5:09 am)
Glad it was that simple!
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- #12 of 25
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Re: Spark Plug Replacement [nosirrahg]
by bena8837
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Sep 08, 2007 (6:26 am)
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Replying to: nosirrahg (Sep 02, 2007 5:19 am)
Well, here I am again! I have replace spark plugs, air filter, fuel filter, and pcv valve trying to improve the fuel economy on my 2002 3.4. After all this, I have noticed no improvement at all. Would a problem with the fuel pump cause this or anything else? Any suggestions anyone?
Thanks
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- #13 of 25
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Re: Spark Plug Replacement [bena8837]
by nosirrahg
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Sep 08, 2007 (5:14 pm)
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Replying to: bena8837 (Sep 08, 2007 6:26 am)
Might not hurt to run some type of fuel injection cleaner through a tank of gas. Other than the standards things like keep your tires aired properly and such nothing else comes to mind. What kind of mileage are you getting? I've noticed the average in my 3.8l 2000 has dropped slightly in recent years, but I think that's largely due to the fact that I pretty much exclusively drive it back and forth to work and never really get it out on the highway like we did when it was the new car that we took on trips...so I attribute mine more to changes in my driving style than anything else.
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- #14 of 25
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Re: Spark Plug Replacement [nosirrahg]
by bena8837
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Sep 09, 2007 (11:15 am)
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Replying to: nosirrahg (Sep 08, 2007 5:14 pm)
I just filled it up again and it's getting to be rediculous, 18.8 MPG. It seems to be going down, I was getting 24 last time I checked before the tune-up, and the norm before that was around 28. My driving habits remain the same, nothing has changed there. I am at a complete loss with this! I will try a fuel injector cleaner and see what happens. Could the fuel pump be a problem? THANKS
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- #15 of 25
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Re: Spark Plug Replacement [bena8837]
by nosirrahg
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Sep 09, 2007 (8:28 pm)
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Replying to: bena8837 (Sep 09, 2007 11:15 am)
The fuel pump might be a problem, but unless you're leaking fuel from the pump I'd think if the pump was bad you'd have more trouble with lack of power. The only other thing I can think of would be the catalytic converter, which several folks have had problems with clogging. But this is typically characterized by a lack of power above say 45 MPH, or an inability to drive the car much faster than that.
One other thing; is there any possibility someone could be siphoning gasoline from your tank? Could be you're wracking your brain trying to fix the problem, and there's some kid in the neighborhood draining off a couple of gallons every now and then. Just a thought. Not sure what a locking gas cap would cost for the Impala, but I'm pretty sure one is available.
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