Poor MPG after recall and alignment


Greetings, I have a 2004 toyota tacoma pickup (prerunner) with a V6. It was recalled in 2004 for ball joints. The dealer where I purchased my PU replaced the ball joints and I was told, performed an alignment. From that day on my MPG went from approx. 30 MPG higheway to 16. Recently I had an alignment performed and now I am getting almost 12 MPG highway. The tires show no obvious or asymmetric wear pattern. They are inflated to the specifications on the decal in the glovebox/owners manual. The tires are rotated every 5,000 miles and the total mileage is 40,000 miles. The reason I think the front end is to blame is that the noticable drop in gas mileage coincides directly with the replacement of the ball joints. Any thoughts?


The magnitude of the change says it is not 100% front end.

Look for other changes at about the same time. Different routes, shorter trips, loss of power, brake pull - these will give you clues where to look.


When this customer comes to you the Service Advisor how do you even start your explaniation that ball joint replacement and alignment did not cause a 18mpg drop in gas mileage? The technical route is doomed to fail.


How much information do you have to back up your 30 mpg claim? If you have enough, you will prevail.

How much information do you have, and what, specifically, is it?

I have to say, 30 mpg for a Tacoma seems a bit much, even on the highway. How were you measuring this mileage? Please document your claim.


I travel to northern California from my home near Palm Springs a minimum of 8 times per year. I travel approx. 2 miles from my home to the freeway. I set the cruise control at 65mph and before the recall would go approx 400 miles on 12.8 to 13.4 gallons of fuel according to the log I keep for IRS purposes. My neighbor across the street has the exact same vehicle (Year, Model, Make) and averages 26mpg. Hers was not recalled. You do the math.


Is this the only time you check the mileage?

Like the others, I’m really hard-pressed to accept that an alignment or the work described could have anywhere near that effect on mileage. I suspect you have other, engine related issues going on but aren’t tracking your mileage routinely enough to be able to see the decline.


I just checked the government-required mileage disclosures for an '04 4-cylinder Tacoma: 22 city; 27 highway. So your claim of 30 mpg highway for the V-6 must be a mistake because it would have to be less than the 4-cyl. Ball joints have no impact on mileage. An alignment would have to be radically incorrect with a ridiculous amount of toe-in or toe-out to affect gas mileage. Therefore, your increasingly poor gas mileage has no connection to the recent front end work. I would try these things: change the fuel filter if you don’t know when it was lasted replaced; same with the air filter; check for frozen brake calipers (any hot brake odors?)


All mileage is tracked and logged for IRS purposes.


I retrieved the EPA window sticker from my files and it states 29 MPG (estimated) and 24 MPG (estimated) are averages and one could expect some variance (plus or minus) depending on driving habits. This vehicle is routinely maintained by the dealer in accordance with manufacturer’s specifications. I am not trying to place blame on anyone, but when it costs $70 to fill this tank here in California, I am concerned and am trying to find out if there is something that will rectify this condition. The vehicle glides effortlessly on level ground when pushed by me. I feel/hear no drag and no brake odors are present after shut down. If it were a brake problem, wouldn’t I be going through friction material at an extraordinary rate? I really like this PU. I can haul my motorcycles in the bed and routinely use it for home improvement projects. I am not a professional mechanic but a professional mechanical engineer by occupation. I have been maintaining my own vehicles myself since 1971 when I began my driving career first out of necessity and later as a hobby. I have rebuilt several of my vehicles including converting stock suspension into independent for better handling. I have rebuilt several motors/interiors/paint. I am perplexed and can only say that this noticable depreciation in mileage (12 vs 27 according to your information) coincides directly with the front end change. I guess the next step would be to purchase a shop manual and trouble shoot this myself to see if the front end geometry is in accordance with that specified by the engineers. Thank you for your input.


If this is not related to the change in ball-joints, what kind of malfunction would yield this change in MPG and not be detected/flagged by the onboard computer? Thanks for your input.


Here are some possibilities.

First, you aren’t using any more gas. You stated how much gas you used per trip before the work, but not after. It could be that a speed sensor has malfunctioned causing a false mileage on the odometer, throwing off your mileage calculations.

Second, you are using significantly more gas because someone cracked a fuel line and you have a leak. This would be a pinhole leak, the stream of lost gas here would be thinner than a horse hair so you might not have noticed it.














As a professional mechanical engineer, you should be able to figure out that the effect tires have on fuel economy is pretty low. If you spend some time googling, you’ll come across several papers that indicate that tires contribute less than 20% of the fuel consumed- and that’s in total, changes would be smaller - so a vehicle experiencing a 50% hit has to have other problems.

By all means check the alignment. But from experience (I’m a tire engineer and retired hobbyist racecar driver), toe in is the biggest contributor to alignment induced drag - and that’s easy enough to check with string snd a tape measure.

And the best advice I can give you is: Be sure you have the “Before” and “After” test conditions as close to the same as possible. Failure to do so will result in your spending a lot of time chasing a “red herring”.