Quote:
Originally Posted by andrewwynn
At about 190k miles I was having high fuel trim end up replacing MAF to resolve but on wife's m54, had Lowe efficient cats and used defouler to smooth out the sensor feedback and get a couple more years out of the cats.
Watch the pre/post volts on a graph. The post cat should not track with the pre cat voltage. If it just slightly follows the cats are worn and a candidate for defouler. If they swing like pre cat they are end of life.
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So while I was out today I wanted to give the X another run on the highway. I started with a long idle rev of about 2500 rpm for a minute because of the lifter ticking I mentioned in another post to you. I didn't hear it on startup this time but I was reading something about a procedure to run the engine at 2500-3000 for 3 minutes for lifter issues.
On my highway drive in sport mode I was hitting about 4000 rpms for as long as I could. I never run my vehicle this hard. after that I was monitoring on ScanMaster and drives at 2500 rpm showed the Bank 2 doing a little better. Bank 1 too. I figured after the two bottles of cataclean and fixing that MAF wire its best to just drive it on the highway and try to burn up any excess carbon I can. I did order OEM plugs and they are on the way.
I don't see any issues when idling. and even idling at 2000 rpm it doesn't match pre cat. Highway driving is a little different but here is 2500 rpms on the highway.
I read that the voltage on up/down O2 sensors pulls down when you break. I didn't know that.