ZJTim

Hi all, I am working on my wifes 99 ES300. It is a little bumpy during acceleration. It has good power even in the upper rpms but it just seems to stumble a bit, more noticeable under partial throttle. It is throwing codes p0500 (speed sensor), p0446 (emissions VSV), and P1153 (A/F sensor Bank 2/1 lean). I have already replaced the 2/1 a/f sensor with a new Denso part. I also checked for vacuum leaks and cannot locate any. The tps sensor seems to be responding appropriately during onboard testing. I am leaning towards a fuel problem (pump, filter or regulator) but I don't have the adapter to test pressure. Can anyone think of anything else to test before I spring for the adapter? Thanks all!

HomerJay

If I understand correctly you still have multiple codes which have not been fixed. I would recommend diagnosing and repairing each code and see if driveability improves.

ZJTim

I listed all three codes but I suspect the drive-ability issue is related to the a/f sensor code. The speed sensor rarely causes the speedo not to work. I could see this causing shifting problems but shouldn't really affect a/f ratio. I have replaced all the VSV's on the car in attempts to clear the P0446 code with no success. I think the pricey charcoal can is the only part of that system I haven't changed. If this is leaking vacuum it could be the problem. I will check that later today. I have had this P0446 code for months, but the drive-ability issue has only recently started.