"Resetting" the MAF vs. CAI install ... where's the hp coming from?
 

Hi all,

While cruising the L99 power loss threads, I've noticed two things that have me wondering.

First of all, these cars seem to respond very well to a simple CAI install, better than I would expect. That's great, but I'm naturally sceptical when it comes to bolt on advertised hp gains.

Second, it sounds like that the simple process of "resetting" the MAF, causing the PCM to learn new idle, timing, and fuel criteria is really waking the L99 cars up, those that were down on hp, anyway.

My simple observation is this: Obviously in the process of installing a CAI, the MAF must be unplugged and then plugged back in, presumably causing the PCM to learn new performance criteria. How muc of the CAI power gains that we're seeing can actually be attributed to the CAI itself, and not the PCM instructing the car to perform optimally for its new driving conditions?

This question is obviously irrelevant when it comes to power increases as a result of a CAI AND a tune.

So am I totally off base? I'm the first to admit that my gen IV small block knowledge is limited, I've mostly just messed around the LS1, so if I'm talking crazy, its cuz of inexperience, not stupidity.

well just unplugging and replugging that MAF won't reset anything the only way to do that is disconnecting the battery to my knowledge, and when you do add a CAI you won't see peak performance instantly because the PCM will take a lil time to adjust to the extra amount of air


i believe some have gotten a gain out of replugging the MAF because it didn't have a good connection in the first place

just my .02

It's possible for the ECM to see knock and revert to the lower timing table it will go back to the high after an undetermined amount of time ... To relearn I would disconnect the ECM wait 10-20 seconds then reconnect ... This is not what I feel to be the problem with the L99 nor hav I found one that has been slow yet ...

I've done some tuning on my 4th gen and am currently running a speed density tune in it (where the PCM ignores the MAF input and determines fuel delivery based on Manifold Absolute Pressure).

From the way I understand it, the PCM is constantly learning and will eventually get to the same point whether you reset the PCM or not. However, by resetting the PCM, you make it forget all of the historical data it uses in its calculations and lets it start from scratch learning your brand new mod, which speeds up the process.

Also, the PCM will not reset simply by unplugging the MAF - Gentry78 got it right in his post above (post #2).

The guys are definately right, installing the cai does not change the maf tables at all. I've even dyno ran our intake without ever unplugging the sensor, just moving two bolts & putting the two bolts into the new intake. It's a easy install. The key to intakes working well is either good marketing, or a well designed part that works well with the factory tuning to lean out the car a little bit while providing better breathing ability. This is the exact reason we went through 10+ different designs before finishing up with one particular design. :) :) :) It's like a little bit of tuning & a lot of better breathing all in one product! :) :)