Drastic change in fuel consumption (bad) after tune up

Reply

  #1  
Old 10-27-12, 10:49 PM
Member
Thread Starter
Join Date: Sep 2012
Location: USA
Posts: 14
Drastic change in fuel consumption (bad) after tune up

I drive a 1989 4X4 Toyota truck with a Small area for seating behind front seat. Its a V-6, 5-speed Manual transmission. It has 145565 miles on it. One owner. Great condition. Always got 30 mpg. Loved it. Decreased to 22-25 mpg in past year. I Took it in for a 60000 mile check up/tune up and mentioned the mileage since that was the only thing that seemed "wrong" with it. $1400 worth of tune up and a CV replaced. Drove it away and went on a 435 mile road trip to a place I often go so I know how many mpg I have always gotten. This time I only Got 16 mpg. Very sad. The mechanic said all the things they say to my gender: it's the way I drove it (I am the only owner and haven't changed my driving recently), road conditions, I couldn't have put on that many miles since they tune it up, I didn't know how to figure out mileage, etc. etc. I pressed him until he said he'd look at it again. What do I need to know before the mechanic looks at it again? Why did the mileage drop after the tune up? Thank you
 

Last edited by sandlake; 10-27-12 at 11:22 PM.
Sponsored Links
  #2  
Old 10-28-12, 03:29 AM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,968
Have you changed timing belts? If not, you are on borrowed time. IIRC, they should be changed at 80,000 mile increments if not sooner. Yours could have just skipped instead of breaking, which I would consider a blessing. If it breaks, you will have a major overhaul of valves, etc, which is $$$. It may not show up on a timing light, as it isn't the engine timing, but the timing between the crank and the valve train.
 
  #3  
Old 10-28-12, 04:29 AM
the_tow_guy's Avatar
Group Moderator
Join Date: Feb 2001
Location: SW Fla USA
Posts: 11,540
I would also make sure they put it on the scanner, not just the code reader, but the one that reads all operating parameters so they can look for issues with the engine running. An '89 Toyota, I don't know what scanner hookup is available or whether the average shop could do it. A dead O2 sensor, for one, can make the mpg's go south, but I wouldn't necessarily condemn without seeing what the operating data looks like.

Is this your regular mechanic who you've dealt with for awhile?

Had to look up the timing belt. If that's a 3.0L, the book says 60,000 miles for severe service (which is a good time to replace it regardless of use). Good news is it's not a valve-bender engine, just a tow-in and repair.
 
  #4  
Old 10-28-12, 04:38 AM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,968
Good to know, John, regarding the valve bender thing. My 1986 Nissan Hardbody had OHV V6, and would have probably not been a nice day if it had broken a belt. I do know my Volvo twin turbo V6 was deep sixed by the belt breaking.....14 of the 24 valves gone.
 
  #5  
Old 10-28-12, 07:42 AM
czizzi's Avatar
Forum Topic Moderator
Join Date: Jul 2007
Location: USA
Posts: 7,124
I had a buddy who drove an older Silverado pickup that only got 8 mpg. Used to cost him a small fortune just to commute to the jobsite (52 miles round trip). He was talking to a friend who suggested he try a Lucas Product (some kind of tune up in a can, can't thing of the exact name) you put in your gas tank at fillup. Hit it on 2 subsequent tankfulls and his mpg shot up to 15. He was in disbelief that it was that simple, but happy with the outcome. Apparantly, engine was gunked up. There are other products that do similar things, gumout, STP treatment, etc. Might be a cheap solution.
 
  #6  
Old 10-28-12, 09:34 AM
Member
Join Date: Mar 2009
Location: Texas
Posts: 1,051
Like The Tow Guy I am thinking along the lines of an O2 sensor also.
 
  #7  
Old 10-28-12, 12:15 PM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,968
Czizzi, yeah I use Lucas in my diesel, sometimes Seafoam and it helps. Doubt it will help boost mileage that much for me, but it does clean injectors. O2 sensor does sound a good place to start.
 
  #8  
Old 10-30-12, 08:59 AM
Member
Thread Starter
Join Date: Sep 2012
Location: USA
Posts: 14
Drastic (bad) change in gas consumption immediately after major tune up

Thanks everyone. This is a new mechanic for me. I am going to show him this communication and hopefully get it resolved. I will let you know how this turns out. You guys are great.
sandlake
 
  #9  
Old 10-30-12, 04:48 PM
ukrbyk's Avatar
Member
Join Date: Mar 2010
Location: USA/ Pacific NW
Posts: 3,220
well, last time I paid for tune up, they installed new spark plugs, plug wires, air filter, and poured few tablespoons of injector cleaner into the fuel rail to clean injectors. $350. I do same now for less than $60, or $100, if I want to go with K&N air filter.
I say, for such a radical drop in mpg, either something was disconnected and not re-connected, usually, something on emissions side (which is likely to throw CEL, but..), or the plugs are not gaped right, or not up to Toyota standards, or wires are not up to same standard, or all of the above.
Airl leak somewhere. Sand, how does the truck drive actually? performance drop should be very noticeable, really. You sure you did not fill her up with wrong octane gas? that will do it either. As if trucks drives fine, performance is fine, no warning lights and such - then it's operator fault, I must say. Traffic condition, etc. Just like mech told you. Happens.
Dragging caliper will do this too. Does not need much to drag. Even low tire pressure.
 
  #10  
Old 10-30-12, 04:52 PM
ukrbyk's Avatar
Member
Join Date: Mar 2010
Location: USA/ Pacific NW
Posts: 3,220
Oh, and running on all four. Definitely.
 
Reply

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


Thread Tools
Search this Thread
Display Modes
'