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Chevrolet Impala Spark Plug Replacement

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!


  • nosirrahgnosirrahg Little Rock, ARPosts: 872
    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.
  • bena8837bena8837 Posts: 26
    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!
  • nosirrahgnosirrahg Little Rock, ARPosts: 872
    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.
  • bena8837bena8837 Posts: 26
    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!
  • 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!
  • nosirrahgnosirrahg Little Rock, ARPosts: 872
    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.
  • 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!
  • nosirrahgnosirrahg Little Rock, ARPosts: 872
    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.
  • 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!
  • nosirrahgnosirrahg Little Rock, ARPosts: 872
    Glad it was that simple!
  • 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?

  • nosirrahgnosirrahg Little Rock, ARPosts: 872
    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 I attribute mine more to changes in my driving style than anything else.
  • 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
  • nosirrahgnosirrahg Little Rock, ARPosts: 872
    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.
  • I forgot to mention that I live on a deadend street and we are all retired. Besides, I can see the needle move as I am driving down the highway. Thanks
  • nosirrahgnosirrahg Little Rock, ARPosts: 872
    I'm grasping at straws at this point. Can you tell if the car is shifting properly? Could be it's not shifting into overdrive, and you're driving around in 3rd gear all the time. It'd be easier to tell if your car had a tach (which I assume with the 3.4 it doesn't)...would also help if the transmission wasn't so darn smooth to begin with. Might try running through the gears manually just to be sure it's shifting into overdrive properly.
  • The transmission and the proper changing of gears is something I am always very conscious about, so I always feel when it changes gears and even try to help it when I am in town, by easying off the gas pedal when I think it's to that point. As for the overdrive, I have been out on the highway and have released the gas pedal and it coast a long way. I have been wondering if the fact that I have not taken any 4-500 mile trips in the last few monhts due to my back surgery, might have caused an accumulation of carbon in the ejectors! Someone told me to clean the MAF Sensor, and I did, but I didn't notice it being very dirty. Also, I have been told that the only way to really clean the ejectors is to have it done professionally with a machine, do you agree with that? I have already put ejector cleaner in the fuel tank. Please let me know. Thanks
  • nosirrahgnosirrahg Little Rock, ARPosts: 872
    Early on I had an injector get clogged on my 2000 (got a message on the dash and took it Autozone to have it read); I took it to the dealer and they charged me somewhere between $100-200 to fix it. Around the same time someone told me they always ran a bottle of fuel injector cleaner through their fuel system every time they changed oil, and never had any problems. I've actually started doing that, and have had no trouble since.

    Getting the car out on the highway certainly couldn't hurt it. I actually started to suggest if you had a grandson who was driving age to turn him loose in the car and he'd more than likely "blow the soot" out of it as we used to say about older cars with carbs back in the day. Not 100% sure the same would work for fuel injected cars, but still probably a good highway run would help it. Even a 100 mile trip would probably be beneficial.
  • I took a 100 mile trip today. When I got to my destination I thought about taking a look at the A/C Compressor to see if it was cycling on/off. I never noticed it to cycle off, is it suppose to, how does it work?
  • nosirrahgnosirrahg Little Rock, ARPosts: 872
    I don't know that I've never noticed mine cycling on/off (either visually or aurally), like I used to in previous cars. I know if I turn the button on the dash on/off I can hear the compressor kick in and out, but in normal driving with it on I never notice it cycling. If could just be that because of your surgery you're not taking longer trips, and over the summer you've probably been running the AC more, which combined are hurting your gas mileage.

    I've noticed over time that my gas mileage typically improves in the summer, but the reason for that is I'm not delivering/picking up kids from school at that time, so even though I'm running the AC more I'm also actually driving more than idling. It's always September when my mileage drops because it's still hot AND I'm sitting in school traffic that I notice a drop and think maybe something is wrong when it isn't.

    If your car has the 3.4, do you have the driver information center that tells you your fuel mileage and such? If you do, one thing you can do is reset it each time you fill up the tank, not only on the gas mileage but on the average speed as well. I've done that since day one on my car, and I've seen a definite trend between lower average speed (due to idling and such) and lower gas mileage. So whenever I see my mileage average is low, I toggle over to the average speed indicator...if it's low too (as in under 30 MPH) then I pretty much know why my gas mileage is bad.
  • I still haven't resolved my fuel consumption problems in my Impala. I just bought a scanner/code reader but am having problems getting it to work or to power up off my car. This is the way it is suppose to work according to the individual I bought it from on Ebay. I have checked all the fuses in the car and they all checkout ok. I have also checked the terminals in the OBD Connector and it appears I have power between terminal 5 & 16. Any Ideas, any help would be greatly appreciated. I have already written the person who sold it to me, new. He has not responded, I just got it today. Thanks
  • nosirrahgnosirrahg Little Rock, ARPosts: 872
    Earlier this summer I had a set of "Halo" spark plugs intalled in my 2000 Impala 3.8l which were supposed to provide a gas mileage improvement, but unfortunately I never saw any improvement, and in fact I had problems show up almost immediately with a missing problem that would kick in when lugging the engine somewhat when going uphill at modest speeds (especially with the AC running). I noticed the metal posts on the plugs where the wires connect to the plugs were the screw-on type, and these tended to work themselves loose over time. Tightening them up would help somewhat, but the problem would never go away.

    I finally got fed up with the missing problem and went and bought a set of AC Delco iridium plugs and put them in this weekend. I started with the #2 plug knowing it was the most difficult, and when I finally got this plug off it was broken. The problem is I don't know if it was broken when my mechanic installed them originally (which IS when my missing problem began), if I could have damaged it mid-summer while trying to tighten the metal posts, or if it only broke as I was trying to remove them this weekend. I doubt I damaged the plug tightening the posts, since the #2 plug is the hardest to get to, and I'd think if I'd break one it would be one of those I could get a better handle on. Either way, I know the car runs perfectly fine now that I've gotten the Halo plugs out of there. I've gotten so accustomed to the car missing at set points on my daily commute that I almost feel like I'm driving a new car now that the problem has been resolved.
  • My firned told me that there this tool that you use by, taking off one of the front motor mounts and replacing it with the tool.the it makes the motor tilt, he says its easily accessed after u get the tool. maybe u can rent the tool , i duunno.
  • As of late I have noticed that eventhough the a/c is turned on when I start the car, it does not come on. I have also noticed that the dash light are on but very dim. After I drive for a bit I notice that the interior dash lights brighten and the a/c starts blowing. This is on a 2002 Base Model Impala 3.4 with 61K miles. I do not get any mil so I have no idea what is going on. Has anyone had this problem or does anyone have any suggestions as to where or what to check? Any help would be greatly appreciated.

  • bsquarebsquare Posts: 1
    I have a 2005 Impala. Lately the dash lights will come on full brightness when the car is started. After about 30 seconds, they will then dim so that it is not bright enough to read, along with the radio, climate control, gear indicator and overhead display. Other times they will act normal. I've tried manually turning lights on, etc. , but it seems to have a mind of its own. Anybody have any thoughts on the issue? I've heard it might be the Body Control Module, but not a real inexpensive "fix" if it is not the fix.
  • I had the same problem with mine changed the plugs and now it misfires any thoughts
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