So im thinking of upgrading my fuel injectors. My wife recalls me mentioning a thread on here about how changing injectors will make the obc wrong on milage and miles to fillup, damn her and her memory. I was wondering if the jcw injectors do that too or only the much larger ones.

and sorry for the major typo's in the title.

 

Neither. The JCW injectors are a good upgrade, especialy with a ECU tune.

 

The JCW 210 upgrade includes the new injectors and also reprogramming, which might correct the mpg calculation errors.

It's logical to suppose that all bigger injectors introduce an error, since the computer will assume a certain flow but it will be more ...

 

I have the JCW 380 cc injectors and the GIAC flash (not sure if that touches the OBC calculations), but my OBC calculations are pretty close to my own 'back of the envelope' calculations at each fill-up.

 

I have this upgrade on my car and the on board computer mileage is averaging 3.1 MPG high.