Poor mileage - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1987-1991 Parley with regards to your 1987 to 1991 Bonneville, Olds 88 or Buick Le Sabre Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

Reply
 
 
 
Thread Tools Search this Thread
Old 06-02-2005, 07:42 PM   #1
Senior Member
Posts like a Corvette
Thread Starter
 
Join Date: Jul 2004
Location: Winnipeg, Manitoba, Canada
Posts: 1,445
Thanks: 0
Thanked 0 Times in 0 Posts
captainmiller is on a distinguished road
Default Poor mileage

Well, I decided to record my mileage since the last tank-up and it isn't pretty. It looks like I'm gettin 15.1MPG as of now. To my understanding I should be getting at least 18MPG? This is all city driving and the O2 Sensor was changed after getting a code 44 a couple thousand km'* back. Plugs are also pretty new, the rest of the things that have been done to the car are in my sig.

Any ideas of what might be causing this?
captainmiller is offline   Reply With Quote
Old 06-02-2005, 10:11 PM   #2
Senior Member
True Car Nut
 
Join Date: Apr 2004
Location: Three Oaks, Michigan
Posts: 4,879
Thanks: 0
Thanked 0 Times in 0 Posts
opensourceguy is on a distinguished road
Default

Do you have a heavy foot? Is this mostly city driving?

I'm thinking the biggest cause of poor fuel economy is needing a tune up, but you have that covered. Clogged cat perhaps? EGR Valve look alright?

When you did a tune up and the CAI and all that work, did you reset the ECU, by chance?


-justin
opensourceguy is offline   Reply With Quote
Old 06-03-2005, 10:39 AM   #3
Senior Member
Certified GM nut
 
Join Date: Feb 2004
Location: CT
Posts: 2,099
Thanks: 0
Thanked 1 Time in 1 Post
SSEBONNE4EVA is on a distinguished road
Default MPG

Heres what I would do. My 90 gets 19 -20 around town.
Install fuel injector cleaner every 6 mo.
Check the TPS voltage at idle. Key on, motor off. should be 4.2 -4.6v.
clean throttle body, IAC, & MAF sensors.
Check if front calipers are sticking, if so clean & lube slides with silglide.
And of course filters filters filters, fuel and air.
And if they are using ethanol in your fuel expect a 2 MPG drop.
SSEBONNE4EVA is offline   Reply With Quote
Old 06-03-2005, 03:54 PM   #4
Senior Member
True Car Nut
 
Join Date: Apr 2004
Location: Three Oaks, Michigan
Posts: 4,879
Thanks: 0
Thanked 0 Times in 0 Posts
opensourceguy is on a distinguished road
Default

To test the calipers, put the car in Neutral, and set the E-Brake. Raise the front end so the wheels are above ground, and rotate the wheels [tires and all]. You should be able to rotate it fairly freely. If you do it in park, this will not work.


-justin
opensourceguy is offline   Reply With Quote
Old 06-04-2005, 02:52 AM   #5
Senior Member
Posts like a Camaro
 
padgett's Avatar
 
Join Date: Jul 2003
Location: Orlando, Florida
Posts: 872
Thanks: 0
Thanked 0 Times in 0 Posts
padgett is on a distinguished road
Default

Driving habits make a big difference as does the late lockup (Reatta locks up at 46 mph but Bonne doesn't until after 50. I mean to fix that someday as there are a lot of 45s around here).

Am getting 18.7 mpg on current tank but all short hops, with 50% Interstate I get over 20. Spouse has a heavier foot and gets less.

Miles also make a difference - after 100k the timing chain has stretched retarding the already ded cam.
padgett is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Poor, Poor GTP!(now with before pics) sse1990 Lounge 22 07-07-2004 01:19 PM
Look at my poor poor trunk, what's wrong with this? TaylorD General GM Chat 19 03-20-2004 08:54 PM
that poor poor neon...like i care! SSEimatt93 Lounge 4 10-22-2003 03:48 PM
poor poor civic LOL SSEimatt93 General GM Chat 6 05-12-2003 11:05 AM
Poor Poor Hollywood :( Tamara 1992-1999 3 11-17-2002 07:28 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 04:19 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.