MPG indicator while driving is not consistent

I have a 2013 Prius with 270K miles.

I have done the EGR cleaning, Intake Manifold, Hybrid battery fan, replaced the PCV valve, and changed the 12V battery. I also changed the spark plugs and the coils last year.

The MPG Indicator in the car is inconsistent. For example, when I'm coasting, it should go all the up to 100, but several times it hovers around 50. I thought that it might be because it an older car and needs to warm up when I start driving, but it happens at all different times during the drive.

I do have an oil burning issue and have been adding oil when needed...is it possible, this issue has gotten worse over the past two years and now this is the new norm?

When I cleaned the Hybrid battery fan about a month ago, the total range went up from 430s to 490s. Since then, every time I fill up with gas, it has come down and is back down to 430s.

My driving is not so different that the driving style should affect range that much.

I'm all out of ideas on what I should do. Anybody have any suggestions?

Raj.

 

Thanks for the reply.

I used to keep track of manual calculations during the time of the cleaning to see how much of a difference it made.

During that time, the range did go from 380s at the lowest to 490s a month ago.

I figured that since it went down to 430s, something must have happened and was curious what I could do. I may end up doing manual calculations, but thought others might have some suggestions as to what I could do to bring the indicated range...at least to the 470s.

Raj.

 

I have all season tires which were replaced about a year ago.

I usually fill up at the same station...the one closest to my home.

I stopped checking the ave mpg after doing it for several months since there was no change. The range went up after cleaning the hybrid battery fan and since it came back down, figured I'd ask about it.

I have not replaced the HeadGasket...how would I know for sure that is necessary?

I didn't know about battery reconditioning and have not changed it. How do I know if that needs to be done? Is there a check that I can do or a shop that can do that will show the battery is the problem?

 

True, but my history is that the indicator shoots up to the top and since it has consistently not done it, figured there might be a problem and wanted to ask what I could to.

Thanks.

 

wish it was seasonal, but this has been going on since the winter so I wanted to ask if there might be a problem so I can take care of it.

Thanks.

 

I did clean the EGR system including the Intake Manifold, and changed the pcv valve...it brought the range up from the 380s to 420s.

I replaced the spark plugs as well...from a reputable shop...def not amazon or ebay.

Tires are relatively new...1 year old.

 

Hi Mendel,

The burning issue has been going on for at least three years. I am one of those who did the 10K oil changes and was told by the dealership and the local shops that everything was fine (even though it wasn't) and then when I asked for a complete check due to mileage was told about the oil burning issue.

Since then, I have kept track of the oil level and added it when necessary. As you can read in the original post, I did do several cleanings/changes. At this point I'm out of ideas so I thought I should ask for suggestions.

Do you think I should get the HeadGasket checked or the Hybrid battery checked/reconditioned?

Thanks.

 

Had it since 2013...just knew about the oil burning three years ago. Was repeatedly told I was worrying about nothing by different shops...until all the problems appeared.

Don't know current, but it was 1Qt per 1500/2000 miles.

Yes, the EGR cleaning was the first...it was massively dirty and painful to go through the entire process.

I don't have hard shake on cold starts...though I did have it a few times almost two years ago...that is when I went down the rabbit hole of cleaning the egr system and other such things.

Will probably get the HeadGasket checked just to be sure that isn't the problem.

Thanks.

 

Yes, the 200-400's was the range.

I used to keep track of MPG and oil burning rate but after a few months of it being the same, I stopped checking.

I'll start again to see where the rates are.

I had to look up LRR tires and to no ones surprise I don't have them on the car.

DENSO 6714318 (671-4318) Spark Plug / Ignition Coil Boot

The above is what I replaced the coils with. Are they good enough? If not, I'll have to look for the coils and see if I can put them back on. Not a fan of dealing with the plugs/coils since I have to remove the windshield wiper assembly.

Thanks.

 

I will get the hybrid battery checked to see if there any problems. When I cleaned the battery fan, I figured I was done, but I guess not.

When the dealership told me about the oil burning issue, they told me about the warranty repair, but since the mileage was high, my car didn't qualify.

I will look into the cost of the Rebuilt or JDM engine. I was thinking just replace the rings, but from your comment, it won't do the job.

I will also look into the Cat to see if that needs to be replaced as well.

Thanks.