Top end work MPG and power down

[4runnerfiend]

Just had two new heads done, Timing belt, water pump, all the idler pullys, fan bering, put Doug thorley headers on. My MPG went from 14-17 to 12 mpg.. only gone thru two tanks. and I feel like there is less power.

Shop says all the bearings being new and tight there is more drag on the motor. VS old bearings all worn out spin more free. (not buying it)

seem normal? maybe there is a break in period?

 

[heat]

Problems with vacuum hoses and/or O2 sensors can do that. My mileage went to ~10 with a bad A/FR sensor.

 

[WeakSauz]

Yeah.. that mechanic fed you a load of garbage to get you to go away. Tight bearings. LOL

I'll second the previous poster with O2s being one of the first things to check.
Vacuum routing too, agreed there. Especially since it was all torn apart.

Check for codes (even if the light isnt on)- Light could be burnt out.

 

[Hopeless Diamond]

Possible the cams aren't aligned correctly?

 

[phattyduck]

Possible the cams aren't aligned correctly?

Either cams wrong or one bank timing belt off a tooth? Both are possibilities.

-Charlie

 

[4runnerfiend]

Thanks for the replies. I think it's ok, did 200 miles freeway and wheeling trip. got 15.2 MPG. for 33's and 4:10 I think that is normal. Power seems fine. Maybe a slight break in period/computer re-learning

 

[nissanh]

Go and tell your mechanic that the bearings are worn/lose again and ask for a refund!!