I've searched but cannot find a straight answer. Does anyone know if it is ok to run the TT 386cc injectors without already having a tune to compensate for the flow increase?

I'm asking because I currently have the APR stage 2 programming along with the test pipe and DV but am looking into going to the stage 2+. Should I install the injectors first then get the tuning? Or should I get the tune then install the injectors after I get home? It's about a 40 mile drive to the shop for the tune, each way.

 

Take the injectors with you, install in the parking lot immediately before you get the tune. If you install them prior to leaving home, you'll run rich (wasteful and potentially bad for your catalyst) the whole way there, because the 386cc injectors are big enough that the ECU can't pull enough fuel out to compensate. If you wait to install them until after you get home from the tune, you'll run lean (dangerous) the whole way home.

 

Thanks for the help. I replaced my cat with the test pipe so I'm not too worried about that. Should I still just wait and change them in the parking lot once I get there?

 

I can't think of a good reason to do it any other way if that's an option.

 

x2 take them with you.

 

Yes you can because the ECU is going to adjust the fuel trim enough to keep the AFR correct for that size injector.

 

Stock injectors are 282cc, 386cc is 37% larger, so the fact that the ECU can adjust fuel by at most 25% means it won't be able to fully compensate. It'll get close, but you'll definitely be running at least a little bit rich, unless I've done my math incorrectly.

 

True if you only using the size of the injectors, but that doesn't take into account what the ECU is already doing for corrections with the stock injectors.

I was going by what the owner of GIAC told me after the very first time he put in a set of larger injectors on a B6 without making any changes to the fueling.

 

Interesting. I wonder if he logged the fuel trims on the car, and if so, if that data is available somewhere. I suppose if the car started out a bit lean with the 282cc injectors, the bigger injectors might end up within the range it could adjust for.

 

I was told the same thing by the APR dealer that I am taking my car to this coming friday. I plan to change the injectors thursday night and then drive it there. He told me that I would run a little rich but it would not harm anything.