Decreased MPG Post Spark Plug and Air Filter Change

so, what was the fix?
if the car was getting over 45 and nothing was changed other then plugs and air filter I don't see how it could be a battery issue...if anything the new plugs should take less energy to fire then worn ones.

 

It's very unlikely the plug gaps were wrong (unless you dropped them ;o), the manufacturers of these high end plugs caution against trying to adjust the gap, and they're properly set at time of manufacture. I too am wondering a bit about "stp performance filter". Still, I think the smoking gun is the battery.

 

IDK, I changed my plugs with the same NKG that were in it and I lost about 4 mpg....my 12 volt battery is less then a year old...air filter is the same, just changed the plugs makes no sense to me...the car has more power getting on the highway so I was wondering what the cause is.

 

Still wondering if your problem was fixed? I have the same issue. Lost 10-12 mpg instantly. It makes no sense that people say battery on an instant drop. Even after I put my old plugs back in it didn't go back up.

 

This an old thread, so you may not get any response from the previous posters.

If you have a scan tool that can display live data, interrogate the engine coolant temperature sensor while running the ICE from cold. If it doesn't show the temperature rising as it should you will need to check the wiring to it and the sensor itself. If you don't find any fault on the wiring, you will need to replace the sensor.

Let us know how you got on.

 

My scan tool displays 36 different live figures but I don't think one of them was coolant temp unfortunately.

 

I find that hard to believe, ECT sensor is one of the most basic sensors.

Maybe you need to add a PID to your scan tool?

 

Low 12 volt battery would impact MPG?

 

Theoretically it could, because HV battery is wasting energy to maintain 12v battery and ICE need to work overtime. And energy and hv battery is drained so ICE need to charger it and MPG goes from exhaust.

Correct me if im wrong. Im a mechanic but never done hybrids untill now im owning one.

 

Best things for "theoretically it could"s are instruments and math.

Stick a clamp ammeter on the battery cable, see what amps go into the battery while driving, multiply that by the volts, divide by 746, that's how many horsepower you can account for that way.

 

Thats definitly true and better than mine theoretically

Didnt know about dividing part. Thx about that