Quote:
Originally Posted by KRAM36
If the ECU isn't getting a proper/full burn reading from the O2 sensors the ECU may attempt to fix the issue with a air to fuel ratio adjustment, however there is only so much the ECU is going to step in on this as the ECU will override the O2 readings with the Mass Air Flow Meter readings and decide to give you a code for a bad cat(s). What do you guess my ECU is thinking about my O2 sensor readings, when I have 200 cell cats in my headers and no secondary cats (although the secondary cats have no O2 sensor after them)? Oh and when I put the new headers on, I also put all new Bosch O2 sensors on the car. The proper O2 sensors, not those kits where you splice in a new O2 sensor. Apparently the cat efficiency isn't bad enough to throw a CEL, but my Durametric will tell me the cat efficiency is below normal. However I did clear all codes from the car yesterday to see if I'm still getting the cat below efficiency warning again. Did you read the part of my post where I said my car eats a lot of gas? Actually, she is quiet a pig when it comes to fuel. The ECU is not attempting to cut the fuel on my car, which is a good thing for this engine as running them lean will kill them quickly, especially with the intake mods I have made, the car gets a lot more air in the intake now.
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since you are being so aggressive about this, its time to call you out for a distinct lack of knowledge.
1. In closed loop, the car is reading the MAF voltage as well as the 02 sensor voltage, as well as half a dozen other sensors to determine how to maintain a stoich a/f ratio.
2. The 02 sensors that are used for A/F adjustment are PRE-CAT. The efficiency of your cats has nothing to do with the a/f.
3. If your ecu has to adjust a/f beyond typically 25%, you will receive lean/rich codes. Again, cat efficiency does not apply.
4. If your car is running rich, then you have some problem, potentially related to your maf sampling tube if you just stuffed in a 987 airbox.
You seem to have basically no clue how modern fuel injection operates, so I'd probably tone down the condescending commentary.