Jungleman

Hello Everybody,,,Been having trouble starting my runner once its warm. It idles really high alot, around 2k sometimes. I had new timing belt put on it but it was doing this a bit before the belt change. I noticed small exhaust leak from muffler. I got a engine light once with po116, coolant sensor, but only once and after reset never again. We watched the o2 sensor output on my buddies hookup and it appears the 2nd sensor doesnt always put out the proper wave. I have changed it once about 30,000 miles ago. But I got engine light and never had any idling probs that time. Anyone have any ideas, Any help I would greatly appreciate. Also I was looking into stainless exhaust all three pipes, I think it was a JBA oversize set up,,,anything I should be aware off.

brian2sun

Get a new coolant temp sensor. It doesn't always need to throw a code to not work properly and since it has already has thrown one, I would say that's your problem. That sensor does affect the idle.

The rear o2 sensor is really just there to monitor the cat's efficiency, the 1st one is the one that gives info directly to the ecu to control fuel mixture and idling. Normally, a new o2 sensor should last at least 85K or so (I got 185K out of mine), so I doubt your rear one is already failing at 30K.

The coolant sensor is pretty easy to replace, just take the plastic timing cover off and then you'll have to remove one bolt on one side of a metal fuel line to get to it. I just loosened the other side of the fuel line and swung it out of the way. Make sure you pay attention to which way the washer is facing on the side you remove (it's beveled). The screws on that fuel line bottom out at a point so there's no torque rating, they just stop.

Jungleman

Thanks Brian,,I am gonna put a new one in tomorrow. I like the front bumper on your truck, I cant find one listed at arb for a 97 runner. Did you use the tacoma model? Have a good one

brian2sun

Thanks, yes it's the tacoma model. They fit perfectly once you grind the frame ends off behind your existing bumper (which is really easy). I was able to use all 4 existing bolts from my stock tow hooks w/o having to do any drilling because I welded the tops and sides where I could easily grind the welds if I wanted to ever remove it. If you don't have a welder, you could drill through the top of the frame and thru-bolt it. Either method is pretty easy, it took me about 1.5 hours to install.

Jungleman

Picked up a "nascar" sensor at autopro today for 50 bucks. Swapped it out tonight and you were right, I test drove it all over town and it worked perfect. Many thanks bro

mpfjax

Just wanted to say thanks to those writing in this blog. I had the exact same problem as jungleman with my 1997 4runner. A friend of mine who is a Toyota tech said for me to clean the MAF, TB and IAC, so I did with no avail. Then he said to replace the IAC. So I did and it too didn't fix the problem. My wife said to get rid of the truck because it has 200,000 miles on it. So I decided to do my own research. I Googled "idle problems with 1997 4runner" and this blog came up. I changed the coolant temp. sensor and it's worked perfect every since.
SO,
Thanks to all!!

brian2sun

Glad to help! That's awesome that the coolant temp sensor is cheap too.

Jungleman

that is cool,,,mines still running perfect and now the boys are helping me with a 1982 landcruiser i am fixin. yotatech is the best