Sorry for starting a new thread but I wanted to have a dramatic title to get attention. For those of you also on Matrix boards, you may want to share this.
For 3 years I have been having idle issues where my RPMs dive down to about 650 at stop signs, and where I can watch the fluctuation occur between gears (mostly 2nd and 3rd) as the auto tranny shifts. I also have suffered from a ZOOMing of the idle when I start the car in the morning. So over these 3 years I have done the following:
1. cleaned Mass Air Flow sensor: no result
2. put in new Denso plugs and ignition coils: no result
3. cleaned the throttle body: no result
4. put on a new orange Toyota redesigned air intake gasket and new PCV valve: no result
5. done a throttle body/engine carbon drip cleaning: no result
So last week, I reported to you that my ace mechanic told me that he discovered where my minor oil seepage was coming from. The seepage was coming from the top of the timing cover. No big deal..........until he told me that I had to have the engine completely removed to replace all the seals to the timing cover. $2200's later, and now eating only Ramen noodles, I notice that my car seems to be running better and quieter. I also began noticing today that I can no longer get the RPMs to dive down below the normal 850 (or so) range when coming to a stop (sign). I also suddenly noticed that my engine wasn't ZOOMing at start up. I just drove to my mechanic and asked them what the heck they did to my car: did they seafoam the engine??? did they put dielectric grease on my ignition coils when they reinstalled them??? did they scrape some hidden carbon out of the engine when they had it out???? NOPE. Turns out, I'm the fourth person to report to my mechanic that we have been suffering from a vacuum leak emanating from the timing cover seals.
So, if you happen to have these same idle issues AND you happen to notice some minor seepage of oil down the side of your timing cover (which ultimately may reach down to the drive belt pulleys, the minor leaks in the timing cover gaskets may be playing havoc with your idle. Not a cheap fix, but I might just save someone from needlessly paying for maintenance on items #1-5 above.)