2018 SR5

[vdavis]

Hello! My husband and I purchased a 2018 SR5 about 2 years ago. It had 20k miles on it. For 18 months we averaged 22MPG.

In January my husband went to New York. Immediately after a refuel the truck started to act strange. It lacked power, wouldn't respond well to acceleration and MPG dropped to about 14. He topped off with gas after getting down to a 1/2 tank thinking it may have been bad gas. For months we took it to shop after shop. One mechanic said the fuel pressure was really high for the truck but he couldn't figure it out.

Took it to Toyota. They dropped a new fuel filter in it and it went to about 16 MPG but still hesitated on acceleration. Went back and asked them to update the software per TSB 0062-18. That took care of the hesitation and power issue. We're still having the lower MPG. I know 18 isn't all that off from the specs, but this is not like this truck.

My question is..... on these trucks, do O2 sensors or fuel injectors ever go bad without throwing a code? Anything else folks have figured out? This was an immediate change and I don't want to accept that it is nothing.

 

[B_Lui]

If it's like the Motronic ecu's from my VW days something that off with fueling will throw a light. The eco should have an adaptation range to bring it back to stoich (say +/- 20% for argument's sake). If it gets beyond the adaptation either way it should throw a code.

If there is another sensor off it could throw a code. I'm not sure how gunked up an injector would have to be to affect mileage without causing other issues.

I hope some part of this can help!

 

[vdavis]

If it's like the Motronic ecu's from my VW days something that off with fueling will throw a light. The eco should have an adaptation range to bring it back to stoich (say +/- 20% for argument's sake). If it gets beyond the adaptation either way it should throw a code.

If there is another sensor off it could throw a code. I'm not sure how gunked up an injector would have to be to affect mileage without causing other issues.

I hope some part of this can help!

Thanks. What would you do, anything?

 

[Herrindude]

With fuel prices the way they are any improvement is worth chasing down. I am assuming you have checked air filter, spark plugs, plug wires ect. Have you tried disconnecting the battery for a while and see if it effects anything? Have you tried fuel injector cleaner and if so, what was the results? I dont know what could cause high fuel pressure? Could a clog in the fuel line raise pressure but lower the flow.? My 1997 tacoma got 400 miles to the tank and them suddenly, it dropped to 300 miles per tank around 30000 miles. I chased it down for years and ultimately just lived with it. Plugs, wires dist cap, cleaning o2 sensors, mas cleaned; nothing helped. Hope this gives you an idea of where to go from here. It just seems suspicious that it happened all of a sudden with a fuel up in ny. If there is water in fuel tank "i" would try 93% isopropyl alcahol in gas, it will help get rid of water in fuel.

 

[B_Lui]

Thanks. What would you do, anything?

I would start with the basics as mentioned above. Plugs, air and fuel filters and go from there. A generic OBD scanner should tell you if there are any sort codes (no CE light) in the ecu that might point to a problem. A vacuum leak could also cause poor mileage.