Lmoyers

I'm planning on installing a vararam intake and probably a cat back system some time in the very near future. I have a 99 c5. Do I need a tune? Anyone know of a good tuner in the Eastern Idaho/Northern Utah area?

dcpatters

I don't know about the vararam, but when I installed an Airaid, it threw off the LTFT's. So much so, I needed to rescale my MAF.

baxsom

I've read a few times that is hard to tune for a vararam on the dyno because you dont actually get the same amount of air flowing through the system. With just the cat back alone, no a tune isnt necessary. Just zero out the fuel trims but unhooking the battery for a while and then the instructions give you a learning procedure to go through. You can always go ahead and get one, will it hurt no. Will it be worth the 500 bucks spent to get it, for the gain probably not.

Gordy M

You need a tune when you change something in the air pump process...the engine is nothing but a large airpump. From air intake to the front O2 sensor is the critical path. Changing air intakes can speed up, smooth out or alter the airpath to the cylinder. The firmware in the PCM is designed to allow a limited range of changes a normal car will encounter. Adding a Veraram alters airflow because in driving, you are getting a cooler air flow to the cylinders, smoother coupler is added also to change the turbulence in the air the MAF measures. All these little items an more causes changes to the original parameters GM coded in the PCM. Tuning allows changes to some of the variable that are not fixed in the tune to increase the efficiency of the engine operation. Cat back will not add any measurable hp because the C5 exhaust is rather well tuned. Adding a Corsa or Borla straight pipe system might add as much as 7 hp but most just change the sound. A common addition is the light weight Z06 cat back exhaust. HTH

Lmoyers

Thanks for the replies. I've researched a bit more and most people aren't saying tune it. But a few are saying to send in the pcm to ECS and getting a mail in tune. Any downsides to that? I'm sure they have done plenty of vararam tunes in the past.

Btw, parts are currently shipping, should be installing the parts sometime later next week

*edit* going to try the reset by disconnecting the battery and see how that goes. Might wait to tune it after I decide if I want more mods.