When Do I Need My Computer Retuned?

[SCREAMINWS6]

Hey. Im an old fashioned carb guy whose into classic muscle, but im looking into LS1 power to build a cheap, reliable street cleaner. My question is, how often do I need the computer retuned and exactly how important is it? For example, if I shove a bigger cam in, without having the computer retuned will it basically make the engine run very similar to stock except with way too much overlap and duration, or will it feed the engine the extra gas it needs and just not be optimal?

[tblu92]

Installing a bigger cam will 1st throw some codes usually --The airflow will be increased to a point where the adjustibility built into the computer won't be enough to cover it all.You typically will be running lean at WOT. At PT the ECM will always try to get you 14. 6-1 AFR, no matter what you've done to it-- However it's range is only +/- 25% SO if it has to adjust beyond 25% it will throw a code and stop. The biggest driveability issue will be the idle. When I installed my cam for example--it would not idle at all !!! I had to change about 10 tables to compinsate for the cam--An A4 is more sensitive at idle than a M6.

[SCREAMINWS6]

So will fixing that be as simple as getting it retuned or do I have to do something else to it as well?

[12secSS]

Well, it depends ... are you going to be doing the tuning or a shop? If you, then tune every time you change anything that affects the fueling. If it is a shop, then only big mods like that BIG cam you inquired about.