Very Bad MPG Blazer Lt -99

Printable Version

Blazer >> Mechanical & Maintenance >> Engine & Transmission >> Very Bad MPG Blazer Lt -99

Page: [1]

Login Message << Older Topic   Newer Topic >>

Very Bad MPG Blazer Lt -99 - 3/22/2008 1:05:06 PM    Swblazer Posts: 17 Joined: 12/21/2004 From: Sweden Status: offline Hello, My Blazer LT 1999 have some problem with the gasmileage. Highway 18 in 65 Mph. (revs around 1900 rpm in 65) City 11 I know for sure that I could get 22-24 MPG on highway before. I have changed tires from 27" to 29", some difference is because of the tiresize change but not that much. Last time I notices that when I stop and put in the Park the idle is high, around 1200-1300 for some sec and then it goes down to 1000. I think idle used to be around 800rpm. Does anyone have the same problem or maybe some hints! On tehe next trip I will hook up my laptop and log some data from PCM, maybe someone can help me read out the data?? I have no SES light on the truck! Regards, /Sverker Post #: 1

RE: Very Bad MPG Blazer Lt -99 - 3/23/2008 7:25:53 AM    BlazerSS   Posts: 139 Joined: 3/25/2007 Status: offline The first simple thing you can do is run some Seafoam through the engine in the oil and gas.  After that, I would definetly clean the Throttle Body in and out with Carb/TB cleaner.  Also check your PCV valve too.  Once you run a whole tank of gas through the car I would put a bottle of injector cleaner in the the next tank of gas preferrably and GM backed 'Chevron with Techron'.  These small things are good a start with a vehicle that has a lot of miles on it and doesnt cost more than $20 + gas of course.  Most of the time, if you have no SES codes, cleaning the throttle body takes care of most high or rough idles.  Also when was the last time you changed your oil, plugs, wires, cap, etc. and air filter?  Axel fluids too! Hope this helps. _____________________________ 2005 Blazer M50 5-Speed 8.5 rear w/3.42 gears Goodyear Fortera Silent Armor P235/75/R15 w/Schrader nickel valves, stems, & caps K&N 63 Series w/Drycharger wrap Magnaflow w/2.5" Mandrel Piping Wait4Me Tune w/93 Octane (in reply to Swblazer) Post #: 2

RE: Very Bad MPG Blazer Lt -99 - 3/24/2008 12:09:52 PM    Swblazer Posts: 17 Joined: 12/21/2004 From: Sweden Status: offline OK! I have changed oil and airfilter for 2 month ago, but not the cap, rotor, sparkplugs and ignition wires! and the truck has 89K on her! So It probobly can make some differens! I drove the truck today without the rising idle, but today it was warmer weather around 35F ?? Will try! Havent had the time to log with my OBDII system just yet! Will happend this week!! /Sverker (in reply to BlazerSS) Post #: 3

RE: Very Bad MPG Blazer Lt -99 - 8/11/2008 3:50:16 PM    Swblazer Posts: 17 Joined: 12/21/2004 From: Sweden Status: offline HI, I might have found the problem.....At least I hope so! Today I hooked up the OBD II and saw that the engine coolant temp Was only around 160F and the gauge is showing around 170F But no Code from PCM?? I will change T-Stat later this week /S (in reply to Swblazer) Post #: 4

RE: Very Bad MPG Blazer Lt -99 - 8/11/2008 5:50:13 PM    portcqb Posts: 410 Joined: 3/13/2008 Status: offline My thermostat was stuck open and it did hurt mpg''s some, mine would never warm up on the gauge or via the OBD2 sensor. I dont think this ever sends a code unless it gets too hot. _____________________________ 1997 Olds Bravada AWD 4.3L Auto ~35,100mi(high idle time), CAI, Quad Beam Moded Mod (in reply to Swblazer) Post #: 5

RE: Very Bad MPG Blazer Lt -99 - 8/11/2008 6:57:01 PM    swartlkk Posts: 15304 Joined: 5/1/2005 From: Waterloo, NY Status: offline That can definitely have an impact on the mileage.  If the engine reaches over something like 165*F it''ll at least go into closed loop operation, but it will not operate efficiently. _____________________________ Kyle- My Restoration Projects Please Do Not PM for Tech Help (in reply to portcqb) Post #: 6

RE: Very Bad MPG Blazer Lt -99 - 8/22/2008 12:09:55 AM    Swblazer Posts: 17 Joined: 12/21/2004 From: Sweden Status: offline Hi, My fight against the MPG.... gas is so expensive here in Sweden (1 gallon for $7,5) Yesterday I replaced my T-stat and now I have 210F on the gauge......Good!! I have also changed airfilter, because I had one of those K&N filters......and I have probably over oiled it!! so my MAS sensor was dirty. I cleaned it with electronic cleaner and q-tip, and after that the truck had more power, Next step will be cleaning EGR valve and change PVC valve. I also checked the cat by give it a good hit with my hand...... and I think it rattles some! NOT GOOD??? (in reply to swartlkk) Post #: 7

RE: Very Bad MPG Blazer Lt -99 - 8/22/2008 8:45:55 AM    bjsx8f   Posts: 21 Joined: 8/22/2008 Status: offline yeah if thats rattling the honeycomb looking cermaic is coming loose into pieces.... I would replace the entire converter if that stuff blows out and ends up turned the wrong way on the way out it could clogg up the exaughst flow and really make things run bad. (in reply to Swblazer) Post #: 8

RE: Very Bad MPG Blazer Lt -99 - 8/22/2008 10:02:39 AM    97ssblazer   Posts: 84 Joined: 8/12/2008 Status: offline i had a similar problem i changed my cap rotor wires plugs fuel filter.... but it turned out to be a faulty ignition module... _____________________________ 97 "SS" blazer ;) [image][/image] (in reply to bjsx8f) Post #: 9

Today's Posts
Most Active Topics
Make A Donation
Forum Rules & FAQ
RSS Feeds

Chevy Blazer Prices

Chevy Blazer
Trailblazer SS

Top 10 Posters
swartlkk 15304 drperry 3927 hanr3 3523 chevy lover 3411 m00nwater 3269 eurogoldls 3121 wolfpack 3074 paddle_grl 2953 hillbillyino 2887 xblazer01 2659

New Vendors
AMSOIL - Performance Oil Technology