Quote:
Originally Posted by cbaber
This thread is old but I have something to add. In another lean burn post it was mentioned that the cat needs to warm up to temperature in order for lean-burn to activate. I know for a fact (for the HX atleast) that you do not even need a cat in order to use lean burn. You dont even need the secondary o2 sensor. After I swapped my engine with a new one I had to replace the exhaust manifold. Long story short, I needed to wait until I got a new direct fit cat for another model to have it cut and welded in to my exhaust. I drove without a cat or secondary o2 sensor (check engine light on) and was still able to go into lean burn. Just thought someone might want to know that cat temperature or emissions past the first o2 sensor have nothing to do with lean burn.
It seems intake temperatures have a huge impact on lean burn. Or atleast for me. Its been about 60 degress or less this week and my car does not want to stay in lean burn for long. No matter how careful I am to keep throttle position low. On monday it was above 75 degrees and I stayed in lean burn the entire trip on the highway with no problems. So it would appear that colder air intake temps can keep you out of lean burn. Can anyone else confirm this?
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With the P07-A01 ecu (probably all 92-95's) intake air temps are not a factor in switching to leanburn - at least down to ambient air temps of 20 degrees F
As long as manifold pressure does not pass that threshold of 4"hg it will stay in leanburn if the other abovementioned conditions are met.
Unfortunately, the later generations are severely emissions restricted.