Last post on Dec 04, 2011 at 5:30 PM
You are in the Chevrolet Impala
What is this discussion about?
Chevrolet Impala, Engine, Sedan
#1 of 27 Spark Plug Replacement
Aug 18, 2007 (4:48 pm)
My fuel economy has gone down on my 02 impala 3.4 after 53000 miles and I am replacing the spark plugs. Is there a easy way of replacing the 3 plugs on the firewall side. Can the engine be rotated, and if so, how is it done? Any help would be greatly appreciated!
#2 of 27 Re: Spark Plug Replacement [bena8837]
Aug 18, 2007 (6:40 pm)
I'm not familiar with the 3.4l so I don't know how much difference in this regard with the 3.8l, but basically on the 3.8l you remove the duct from the air filter to the engine, remove the two braces connecting the forward part of the engine to the front frame, then put the car in neutral (blocking the wheels, and parked on a level surface) and then tilt the engine forward. I got a ratcheting strap and put the bolt back in the bracket on the passenger's side of the engine, and then used the strap to basically pull the engine forwards. This doesn't open up a great deal of room, but it makes it a little easier.
On the 3.8l the #2 plug is VERY difficult to get to, even with the engine tilted. I finally gave up and had my mechanic install my plugs. However, I tried a set of "halo" plugs that were supposed to increase fuel economy but which made no difference, and have actually resulted in the car missing when lugged slightly, so I'm probably getting ready to take them out after a very frustrating summer and replace them with a more standard plug. But I'll probably wait until the weather cools down a little, knowing how frustrating the process can be.
#3 of 27 Re: Spark Plug Replacement [nosirrahg]
Aug 19, 2007 (5:49 am)
Hi & thanks for the quick response. How many degrees does the engine rotate, more or less? I have already replaced the air filter, do you think I need to replace anything else to improve MPG? How difficult is it to rotate the engine back in place? I just had back surgery and can't use too much strenth!
#4 of 27 Re: Spark Plug Replacement [bena8837]
Aug 19, 2007 (11:21 am)
I'd ballpark the engine tilt at maybe something like 5- to 7-degrees; nothing too dramatic. I tried to tilt mine back yesterday fiddling with that #2 plug, but I didn't remove the rubber piece between the engine and air filter, and that definitely restricted the movement somewhat.
As for your back, tilting the engine will probably be less of a strain on your back than simply trying to reach those back three plugs. I replaced my plug wires about a month ago (didn't tilt the engine that time), and found it easiest to simply crawl up and practically sit on top of the engine, because I couldn't reach across from either side to accomplish what I was trying to do. My advice would be to have a mechanic replace your plugs; that's what I ultimately ended up doing (I think I paid something like $100 for labor plus the cost of the plugs, which would be worth it versus messing your back up again).
The only other thing I can think of on improving gas mileage would be to replace your fuel filter if you haven't done that. Otherwise I'd say keep your tires properly inflated and try to drive as smoothly as possible.
Another thing to watch out for; several people have posted problems here with their cars not running well as they get some mileage on them, particularly not being able to reach highway speeds. Almost invariably that turns out to be the catalytic converter clogging up, which should be covered by your warranty for well beyond the standard 3-year/36-month warranty. Just something to keep an eye out for if your lower gas mileage starts to lead to reduced performance.
#5 of 27 Re: Spark Plug Replacement [nosirrahg]
Aug 21, 2007 (5:44 am)
A million thanks for the info. I am going to try and tilt the engine today to see if I can replace the 3 next to the firewall. As you said 5-7 degrees is not that much, so I might end up taking it to someone to replace them. I will be replacing the fuel filter also. As for the catalytic converyter, I don't believe I have a problem there because the car accelerates very well and I don't have a problem getting high speed. I really appreciate the help!
#6 of 27 Re: Spark Plug Replacement [nosirrahg]
Aug 31, 2007 (7:53 pm)
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!
#7 of 27 Re: Spark Plug Replacement [bena8837]
Aug 31, 2007 (8:04 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.
#8 of 27 Re: Spark Plug Replacement [nosirrahg]
Sep 01, 2007 (4:41 am)
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!
#9 of 27 Re: Spark Plug Replacement [bena8837]
Sep 01, 2007 (9:06 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.
#10 of 27 Re: Spark Plug Replacement [nosirrahg]
Sep 02, 2007 (5:09 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!