Greetings my friends. I know a tuner is recommended when you do a cam swap, but is it absolutely necessary? Will the O2 sensors, and the ECM, compensate for the increased flow rate through the engine, and adjust the AFR accordingly? Thanks in advance for your replies.

 

No, the cams are likely to take the Air Fuel Ratio outside the range of the narrow band O2 sensors, and the short term AFR is based on the ECU mapping, not O2 - the tuner will correct the mapping for the cams.

 

So a tuner has to be employed if I do a cam swap, or use wide band O2 sensors?

 

A tuner is needed with a cam swap, either a standard tuner and a dyno tune, or a tuner with a autotune system, which uses wide band O2 sensors.

 

No advantage to using wide band sensors with the stock ECM. If it was only that easy.
I'll assume you're installing cams for better performance and the only way to get the most out of them is with a good tune. So to answer your question, a tuner is necessary.

 

Each different cam changes the timing of the valves opening, how quickly they open, the length of time they stay open, how far they open, and how quickly they close. No way you can get by without a tuner in my opinion.

 

You won't get the full benefit of the performance cams with the stock air cleaner & exhaust. You will need a tuner as well.

 

The short answer is no unless the specs of the new cams are nearly identical to the old cams (then why change, right?).

The AFR is based on the VE's. Until the VE's are set correctly (and that can't really be done until the cam setting - IVO at least - is correct), the AFR probably won't even be close.

 

did you earn your 1981 posts in the games section?
I would expect this question from a newb. Of course you need to re tune with a cam change.

 

Cams need a good thorough tuning, as I understand it, more than just AFR, but could benefit from adjusting ignition timing and everything as well. Not something you can just slap a canned power commander map on.

If you're going that far, why not pay the extra dough for a good tuner and get it running like a top?