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15 Mpg
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impala2k
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PostPosted: Sat Feb 02, 2013 4:48 am    Post subject:  15 Mpg Reply with quote

3.4l v6 109,6xx miles. Tuneup around 85,xxx (all Delco parts). Transmission seems fine like 85% of the time, a slip every 6 months or so. No matter how hard or how easy I drive it always right around 15 mpg. I am lucky to see 15.5. This car confuses me.... It's almost as bad as my friends '73 Chevy truck with a 350. It's been cold 30 degrees F or less. Engine never seems to warm up maybe 160 degrees. I may try to block off the grill somehow to keep heat in, but 15mpg is unacceptable to me. Ran some seafoam through the tank to see if injectors were dirty, but no improvement. No codes and engine seems to run great, in the cold I do get some voltage issues but everthing smoothes out after engine temp gets a bit higher. Don't know what to do. Maybe I should put a cat-convert back in, as i imagine it could keep some heat back towards engine. Could put a higher temp thermostat in but T-stat is pain to replace. Just lost at this point. Could it be the bigger Throttle body since it isn't port matched to intake mani? Maybe running less efficient than stock tb which is?

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Lingenfelter
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PostPosted: Sat Feb 02, 2013 2:11 pm    Post subject:   Reply with quote

City? Highway? What parts specifically have been changed?

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impala2k
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PostPosted: Sat Feb 02, 2013 3:10 pm    Post subject:   Reply with quote

Lingenfelter wrote:
City? Highway? What parts specifically have been changed?

Mixed, but a little more city. I am assuming you are talking parts changed during tuneup? Plugs, wires, pcv, upper cylinder flush or whatever they call it, around the same time changed the T Stat. Oil has always been changed before or right around 3000 miles. Air Filter is cleaned on a regular basis. Tranny fluid changed just after I got it with 7x,xxx miles. On the other hand if you were talking about "Mods" Cone filter, 65mm TB, Milzy PCM, Downpipe, No cat atm didn't have the funds to replace at the time of its demise, and 2.5'' all the way back. Think that's pretty much it.

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topgun
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PostPosted: Sat Feb 02, 2013 3:25 pm    Post subject:  milage Reply with quote

is the MPG better in warmer weather? I loose two or three mpg in winter. Cool

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impala2k
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PostPosted: Sat Feb 02, 2013 3:30 pm    Post subject:  Re: milage Reply with quote

topgun wrote:
is the MPG better in warmer weather? I loose two or three mpg in winter. Cool
Seems like it but it never used to be this bad in winter. Before it got cold it was around 18 Mpg. When I originally got the car unmodded, I remember getting over 20 on avg, and like 26 on the highway. Fuel filter was changed at around 90k miles.

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98ss
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PostPosted: Sat Feb 02, 2013 3:41 pm    Post subject:   Reply with quote

If there is a rough idle and it smooths out after it is warm it could be a lim. If it is truly a voltage issue, then that can also take away from fuel mileage because the sensors will be reading not what they should because of the voltage drop.
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SuperImpala00
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PostPosted: Sat Feb 02, 2013 5:17 pm    Post subject:   Reply with quote

I'd definitely get the charging system checked as well as the battery cables looked at. I just dealt with this same problem and found out my positive cable was pretty corroded, cleaned it up and car runs much better with mpg back to around 20.
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impala2k
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PostPosted: Mon Feb 04, 2013 3:15 am    Post subject:   Reply with quote

Well, me and a buddy figured out what's wrong with the car. I am 4 miles away from 110k and it happened. LIM has failed. It is leaking on the passenger side of motor, and pooling on the head, then running down. It was a rough start leaving his place. SO my question, I have a shop thats well known, that can do it for around $1000 Is it that much cheaper to do it yourself? My buddy said he would help, but if its not a whole bunch cheaper to do it yourself than i will have the shop do it. It's a sad day.

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SuperImpala00
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PostPosted: Mon Feb 04, 2013 9:33 am    Post subject:   Reply with quote

It's really not all that difficult. You can get the whole gasket kit from WOT-Tech for $100. Plus I'd pick up the pushrod removing tool made by Lisle, it pops the lifter off of the pushrod so you don't have to mess with loosening the bolt and than having to tighten it again and risk stripping it. A write up is on gaownersclub.com, I do believe that'll walk you through the whole process with pics. Plus as usual any questions you have specific for the Impala will be happily answered here.
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TeenBeach
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PostPosted: Mon Feb 04, 2013 9:42 am    Post subject:   Reply with quote

Don't waste a grand dude! It's really easy, just have to take your time and be organized. Besides, you will have a load of fun especially if you have a buddy with you. Bring out the brewskis!

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PostPosted: Mon Feb 04, 2013 12:20 pm    Post subject:   Reply with quote

When I did the LIM on my Intrigue I was in for about 300 bucks worth of parts and fluids. A big chunk of that was for a new UIM to replace the cracked one that was on the car. I know you have a 3400, but you should easily be able to do the job for 200 bucks and a day of your time (as long as there aren't any other issues you find along the way). Just make sure you have a quality torque wrench and a firm grasp on what you need to do before tearing into it.

I'd also recommend using boxes to keep bolts and other items organized so you don't lose something or forget where it belongs.

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PostPosted: Mon Feb 04, 2013 12:40 pm    Post subject:   Reply with quote

IffyG wrote:
I'd also recommend using boxes to keep bolts and other items organized so you don't lose something or forget where it belongs.


This and Tape + marker is you best friend for wires.

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PostPosted: Mon Feb 04, 2013 1:24 pm    Post subject:   Reply with quote

Don't forget to order the metal gaskets and not the plastic ones.

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2001 Chevy Impala- 186K Retired: 180 T stat, HV3, Wizaired Intake, GMPP Exhaust, Speed Daddy Headers, 1.9 Yella Terra Rockers, Custom LED interior, BBEngineering.com 6 Pod Cluster, Poly Mounts and Bushings, Dyno Tuned by Dyno Brian @ Dyno Tune Motorsports 181 WHP 230 WTQ
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impala2k
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PostPosted: Mon Feb 04, 2013 2:55 pm    Post subject:   Reply with quote

Wingman520 wrote:
Don't forget to order the metal gaskets and not the plastic ones.


So this is my only car and have to do this asap. Do you think I could get the metal gaskets from a parts store like carquest? Is there a part number? also besides fluids and gasket set is there anything else I have to replace?

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PostPosted: Mon Feb 04, 2013 3:20 pm    Post subject:   Reply with quote

impala2k wrote:
Wingman520 wrote:
Don't forget to order the metal gaskets and not the plastic ones.


So this is my only car and have to do this asap. Do you think I could get the metal gaskets from a parts store like carquest? Is there a part number? also besides fluids and gasket set is there anything else I have to replace?


most likely yes since i got mine at advance auto. I'll check and edit this post with a link along with a part number for carquest for ya.


**edit** found it Carquest

Engine Intake Manifold Gasket Set

Part Number: MIS16203A


as far as other parts I'd get some coolant elbows since your going to be removing the water pump and those break almost EVERY time... Didn't happen with mine, but if you don't yank the pump off and just take your time wiggling the pump out then they might be in once piece. I replaced them regardless though.

**edit** not seeing them on carquest but of course they aren't the easiest part to find... When i get them at advance auto they come in a pack and usually located in the HELP! section which has common replacement parts

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2006 Impala LTZ 105k- Dynomax Catback Exhaust, Overkilled by Will Wink

2001 Chevy Impala- 186K Retired: 180 T stat, HV3, Wizaired Intake, GMPP Exhaust, Speed Daddy Headers, 1.9 Yella Terra Rockers, Custom LED interior, BBEngineering.com 6 Pod Cluster, Poly Mounts and Bushings, Dyno Tuned by Dyno Brian @ Dyno Tune Motorsports 181 WHP 230 WTQ
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