I travel the highway at 55MPH turning 2250RPM. Would I get better MPG if I went 50MPH turning 2000RPM? (I have no O/D)

 

Maybe.

Why no overdrive?

 

I think it was DrewActual that pointed out that people pay too much attention to RPMS when worrying about gas mileage... There is a detailed thread about it somewhere....

 

Yeah engine load combined with RPMs is the deciding factor.

 

when going up a hill on the highway i guess going faster is better for mpg? but while on a straight flat highway 50mph is good?

 

The real question is why don't you have overdrive? Overdrive would be handy on a nice flat stretch of road at cruising speed....

 

solenoid is toast i think. something electrical went wrong. i am getting 15mpg currently going 55 turning 2250

 

I wouldn't expect much more. That's fairly good.

With my setup best MPG I've seen on the interstate with OD was 16.5 mpg- that was before I removed a clogged cat... Still haven't done anything with the pre-cat O2 sesnor..

I might see a squeak better now....

 

i think my cat is gutted. and i only got the pre-cat o2. i think i want a new 02 sensor cuz my city mpg is horrible. like 5-8mpg average city. the new map sensor helped a lot too

 

You might also want the rear O2 sensor, I think it has a small role in MPGs.....

That is some bad city mileage, overdrive won't help there though..