Next thing I'm working on with this 05 Toyota matrix is gas mileage. Sometimes it is really hard to start. I recently put new tires on it from Firestone that seem to be softer than the other tires I got at discount tire. The discount tire tires were quite hard rubber so I remember going faster off the line and a little better gas mileage. Is it possible that new tires that are a little softer would give me poor gas mileage like this? I know that's a little anecdotal let me try and clarify. I think I'm burning about an extra half tank a week with this car right now. That's approximation
If you haven’t already, -
1. Perform a complete tune up.
2. Check mpg using the full tank to full tank method while out driving on the highway for atleast 2-3 hrs.
3. https://carkiller.com/scottykilmer/howto/mpg/
If tires are worn down, they will often ride much harder, The new tires could also be a softer compound.
Some tires are also rated for low rolling resistance, that means better mpg.
Try to set the trip odometer and get an exact mpg, otherwise it is somewhat hard to tell how bad your gas mileage actually is.
@nlord well I can certainly tell that there has been worse gas mileage. I just wonder if there's something else going on like fuel injectors or something? Car does have 230,000 miles on it
@nlord well I can certainly tell that there has been worse gas mileage. I just wonder if there's something else going on like fuel injectors or something? Car does have 230,000 miles on it
@mark88 Check the faq for more info, but start with some easy tune up items. Clean the throttle body, Maf sensor, make sure the air filter is clean, replace as needed. If the spark plugs are old, change them. I did not initially answer these, as you seemed to indicate that the poor gas mileage started when you got new tires, is that correct?
@nlord I mean that's what it seems like happened but you know how things go. Sometimes there's coincidences when things change as well.
@nlord the spark plugs are pretty new but I will go and check the mass airflow sensor and the air filter.
Another odd thing that I notice is that my RPMs drop below 1000 when I'm at a stoplight. And then when I step on the gas the car seems to hesitate a little bit and struggle to get going compared to when the idle is 1,200
Car does have 230,000 miles on it
Even if you think it might not be pertinent, your car's mileage is relevant in most assessments and should be included in it's initial description as can effect one's analysis.
The discount tire tires were quite hard rubber so I remember going faster off the line and a little better gas mileage.
A softer tire is usually faster 'off the line' and has a higher rolling resistance.
Is it possible that new tires that are a little softer would give me poor gas mileage like this?
Sure it's possible. Softer tires typically do have a higher rolling resistance than harder tires. Older tires have lower resistances than newer tires of the same type.
Knowing what your actual gas mileage was before and after the new set of tires would be helpful.
"The Department of Energy estimates that 4 to 11 percent of fuel consumption is due to tire rolling resistance"
@nlord okay I cleaned the MAF and it didn't look too bad but I sprayed it a few times just to be sure. Also the air filter looks fine.
@hixter 4 to 11% is quite a bit actually. I will try to calculate my MPG. Currently I am at 227,337 mi at a full tank
@mark88 Oh I agree. Lower resistance tires can provide better gas mileage. Just just how much of a difference does it actually make? Check out the following article: https://www.consumerreports.org/cars/tires/low-rolling-resistance-tires-can-save-you-money-at-pump-a1547901110/ " a 10 percent drop in rolling resistance equates to about a 1 percent improvement in fuel economy". A poorly performing engine would easily erase any benefit derived from lower resistance tires. Check for performance issues, scan the car and check the live data, the fuel trims.. see if something isn't amiss.
At this mileage of this vehicle I'm also concerned about transmission slippage. Sometimes when I step on the gas the engine goes faster than I think we are. But since I've never had a transmission go out I'm a bad judge of that I think
At this mileage of this vehicle I'm also concerned about transmission slippage. Sometimes when I step on the gas the engine goes faster than I think we are. But since I've never had a transmission go out I'm a bad judge of that I think
Using a higher RPM to maintain the same speed is a telltale sign of a slipping transmission. Cars with slipping transmissions consume more gas because the engine has to work harder to maintain speed.
You have 227K miles on a nearly 20 year old car.. So just hope your transmission is just low on fluid and not going out. Tires compounds are the least of your worries as your car could easily (and likely) be near EOL.
@hixster I will check the AT fluid, but I think it's fine. It was the last time I checked....
This issue is fine now (I think) I will close the case. Thank you for your help everyone.
Mark
@mark88 Thanks for letting us know, hopefully you got it resolved.