Recent Jasper Install

A little more than 2000 miles ago, my engine went out at 126k on my 2006 Dbl cab 4.0L. I ordered a Jasper replacement at $3,800 for the engine alone. I have over $6k invested in the replacement. I am getting TERRIBLE gas mileage now. None of t he fuel system was replaced and prior to the new engine, I was getting 16mpg. I am now getting 11.5mpg which is terrible mileage considering I do not have a lift or oversize tires. Stock size tires and stock shocks, etc. any help or advice is appreciated as I need to resolve this or the truck will be heading down the road in trade for a full size that gets better mileage.

 

Did you break the new engine in? Need to seat the rings. Just a possibility

 

The install was done by a Jasper dealer, and the only thing he told me needed done was to change the initial oil at 500 miles, which I did. Is there something else I need to do?

 

You should read up on how to break in a engine. Everyone might have their own recipe, but basically you need to seat the rings asap.

You need to get the engine up to operating temp and go find a road with no one around. Romp on it in 2nd and 3rd and take the rpms fairly high (dont red line it) then leave it in gear and take you foot off the gas and let the gear slow you down. This will suck the rings against the cylinder wall and will "file" some of the cross hatch down, seating the rings. Then repeat. That is why you do the early oil change, since there will be very tiny iron particles in your oil.
Not saying this is your issue, just something that a fresh engine needs if they didn't already do it for you.

 

Have any check engine lights?

Does it idle smoothly?

Have you checked for vacuum leaks?

Have you checked over their work?

 

How does a 1GR crap out at 126K?

 

No check engine light. It has a slight roughness at idle that you can barely feel in the steering wheel. I will try to search for a vacuum leak this evening. As far as checking their work, I have glanced at it and nothing sticks out to me.

 

I bought it used and have changed the oil but apparently the owner before me must not have maintained it the greatest. Plus, I only commute 4 miles to work one way and that isn’t the greatest for any engine. I’ve owned it for 7 years probably so the mileage is something completely new since the engine swap.

 

Aha. That makes sense.