Hello everyone. I wanted to share with you the troubleshooting I'm going to be going through to diagnose the only real problem I have ever had with this car.

So it's been taking a little longer to start all winter; it is about time for a full tuneup, so I thought nothing of it. I've been getting 28-29mpg instead of my usual 30+, but the winter has also been a little more severe this year. The real problem began a few weeks ago, I was driving gently away from work, since it was about -5 outside (celsius). I tried to escape certain doom as someone ran a red light and nearly hit me, and I had a near miss because the car hesitated like it never has before. It felt like I had run it into a brick wall. Once it realized I was at WOT, it took off, but it did it again a few times on more mild acceleration. As soon as the car was warm it was fine. Naturally, I figured a sensor had gone awry so I took it to Auto-zone for a diagnostic with the OBD2 reader (note that my CEL has been on for almost 2 years due to a failed catalyst, so when I suspect something's wrong I have to get it checked for more codes). The only extra code besides the catalyst code was C1224; something about a real wheel speed sensor, I doubt it's related to hesitation, and the code went away the next day and has not returned.

It had a few normal days, but then this morning it did something really odd. I started it, it barely stayed running. It idled at 400 for about 5 seconds, coughed it's way up to 700, stayed there for 20 seconds before finally started fast idling at 2200, which is REALLY HIGH for 3C. Usually it only fast idles that high when it's -10 or less.

My initial suspect is water temp sensor or TPS; luckily I have a friend at the dealer who is going to hook up a full blown diag computer to my car tomorrow to take some readings before I start throwing parts at it.

...I am aware that I'm due for a tuneup anyway, especially with my driving habits (I drive it like I stole it), but I've seen quite a few inconclusive posts about this relating to higher mileage Toyotas in general, so I thought I'd document the methodology. (And my 20v 4AGE in my AE86 behaves similarly on a cold start, so I'd like to get to the bottom of this).

I also want to brag about how reliable my xB has bee to me. I have literally done nothing but minor maintenance to this car so far, and not very much of it. At 110k miles I installed a new water pump and accessory belts, and changed my spark plugs. I seafoam it every 30-40k and change my oil every 10k with Amsoil OEM Synthetic. This engine is a miracle, I drive it like it's stolen and doesn't burn even 1oz of oil between my oil change interval; that's right, I've NEVER topped it off ever. Also original clutch, like a baws.

 

Looking for updates. I dont have any problem right now @230,000kms but I feel the same about the reliability of this engine! This is a miracle

 

If you've got a failed cat, you might want to gut it or replace it. Could be plugging up. It should cause reduced power all the time instead of sporadically, but it can't be helping anything.

 

Exactly! Or atleast replace it by a straight mid-pipe

Worn out cats are prone to clogging, if so, performance are reduced by a restrictive flow. Thats the first thing.

If I can give you some tips;
-Inspect the engine air filter, or simply clean/replace.
-Remove&Clean your MAF (mass air flow meter), location:Airbox. This sensor play a good role in your air fuel mixture.
-Inspect or simply replace your spark plugs.
-Spend 40-60$ and get your throttle body removed and cleaned througly.

Good luck!

 

Thanks for the replies everyone... I tend to suck at forums, so it's a miracle that I'm replying at all. It was totally just some build up in my throttle body and ISCV. I'm at 209k miles now and still no hiccups!

...Except at 205k the brushes in my alternator were shot. I replaced them for a whopping $10 and I think I'm good to go for another 205k miles.