Anouther exhaust question..... I ordered a off-road h-pip and new cat-back, i was wondering if mil eliminators are necessary, They say wen the cats are removed the mil eliminators will keep the the check engin light from come on, and return it to the perfact 14:7:1 fuel/air mixture.
More than likely you will need them. no cats = CEL. I paid the extra money and bought the ones that plug right in. Well worth it. took me 5 mins to do.
14.7 af ratio Personally I think that's too lean.
MIL's will keep the CEL off that is what they do they go on the rear o2 sensors. If nothing else it bets having that light shine at you.
You can save some $$$ and do what I did. Go to http://www.mileliminatorsonline.com. They're a pretty good deal and free ship too. Plus, the plug and play (like those above) don't work half of the time. I know tons of people that have tried the ones from the mentioned website and never had a problem.
I used the splice in kind, I got them for like 2 bucks each off eBay. They worked great for a year while I had the Mac O/R H on there.
The rear o2's don't specifically modify the A/F mixture normally. The front o2's do that. The rears just monitor the efficiency of the catalyst (the converter) system, and report back to the PCM with its findings. However, if the PCM receives "not normal" results back from the rear o2s for a certain period of time, it will briefly switch lean, then switch rich, to test to see if the rear o2 sensor responds with the result the PCM expects. If it doesn't get the expected result back, the MIL comes on.
Basically, yes they are necessary. If the MIL is on, and something else goes horribly wrong, you'd never know, since the MIL was on already anyway.