Tune the Car to the chip, or chip to the car?


New Member
Feb 8, 2002
Ive been doing a lot of reading on tuning and chip creation. It seems like you can do a lot of tuning with a good scan tool and the mechanical adjustments of your car. My question is, once you tune the car to the correct fuel pressure, boost, etc where is the cut off point of what can be changed mechanically and what has to be changed within the chip itself. It seems like you can get to the same point with either chip tuning or mechanical tuning. Which is best, or is the combo approach the best. Ive looked for some faq or doc that says, These are the baseline tuning parameters, tune +/- to these numbers for your setup, then tweek this via chip. Not had any luck with that one of course. Anyone wanna take a stab at that?


I would say that you want to start with tuning your car using this info:

Quick Reference


then tune your chip to the car. Just like get these cars from the factory some ran better then others, just depend how everything was put together ( how well things lined up, adjustment on parts, and others).

Also the combo will make a difference ie (you have a t54 turbo, stock injectors, stock exhaust). You will be able to tune to the combo's ability but you need the right combo for peak performance.

In short have a good combo, tune the engine, and tune the chip.

I'd wagger 90% of all the mechanical tuning is because folks pick too small of injector for what they want to do.

ie they fall prey to the .5# injector per HP. Which is fine for the aftermarket and race cars but wayyyyyy off for using the oem ecm.

If you using a stock ecm and want to make 2x the HP then you HAVE to use 2x more injector, are you'll wind up chasing the BL numbers all around.

Then if you want to run seriously larger injectors, then bite the bullet and modify the ecm to run P+Hs. They turn on and off faster then the saturated ones, so you can more accurately tune them.

Of course the easy way around things is going with an extender, and translator plus.

You tune to keep the engine happy. ie you have to use a timer, the watch never lies......