legokcen

I've searched through the threads for this and have done a good bit of the suggestions. I've still got the issue so I wanted to ask for additional advice on next steps.

The truck is a '97 4Runner, Auto, 177,xxx miles. I've had it for about 5 trouble free and wonderful years and she's a great truck. Recently (~month) I've been experiencing a high idle when I start it up. The idle will be anywhere from 1200 to 1800 rpm. Also, when she is hot, she sometimes doesn't like to start. In the morning, she'll start right up with no problems. Just the idle will be high. If I have to shut her off and then restart shortly thereafter, sometimes she won't start on the first try and I'll have to turn her over several times to finally get her to catch. A few times, it has been fruitless and I've given up and taken another car or was temporarily stranded. I smell fuel when this happens so she is obviously getting gas. Sometimes after the hard start problem, after it finally gets going again, the idle is fine and smooth for the duration.

Things I've done:
1. Pull apart the intake and clean the MAF, Throttle Body, and Idle control valve under the throttle body. The TB and ICV were pretty dirty.
2. Replaced the Fuel Filter
3. Pulled the EFI fuse and waited 30 minutes (fired up afterwards, but still high idle)
4. Removed all power to hopefully let things reset (still no fix)


I haven't checked fuel pressure, but after starting, power seems ok and she revs high and pulls like normal.

Last weekend when I had the hard start issue, I pulled the EFI fuse and put in back in. She fired back up. Weird, but worked. Still high idle though and the hard start problem isn't gone.

I'm kind of stuck now and would like some suggestions as to the next course of action. What else should I check or where else should I hunt? I'm mechanically inclined and have most of the tools to do what I need for part replacement. I love the truck and want to keep it as long as I can.

Thanks in advance for the help.

kball

I take it you have no CEL? Maybe scan it anyway to check for pending codes. Did both the high idle and hard start when hot begin at the same time?

legokcen

No, I don't have a CEL. I'll pull codes to see if there are any that are pending though. The high idle started a while before the the hot start problem did. They were maybe about a week apart. Some of that difference could have been that I would drive it to work and then back home. It would give it time to cool back off and then would start up fine.

I'll put a code reader on it tonight and see if it says anything.

kball

You may have multiple issues. Gerdo just fixed his hard start when hot problem with a new fuel pump but that would not cause your high idle.

J2F42C

Test the ECT (coolant) sensor per the FSM.

If it is out of range, it could cause a high idle, hard hot start.

I don't have a link to the FSM at the moment but fellow member rworegon does under his sig.

legokcen

I think I've got it now.... I put my scanner on the car but didn't see any pending codes. There is a "DataStream" function on the scanner & when I went there I believe I found it. The Engine Coolant Temp reads -5 degrees C and the idle kicks up high and the advance moves to ~20 degrees. The temp will then show normal for a few seconds and the idle will go back to normal. I tried stopping and starting it a few times and when I cut it off, the temp read 80C and the car started fine.

Next item to change, Engine Coolant Sensor.... Hope that works... it's a $20 part at Advance/Autozone. Is there a brand that is recommended or works best?

rworegon

Is engine a 3.4? Remember, the Engine Coolant Temp sensor talks to the ECU and is not the temp switch for the temp gauge. The FSM also shows a gasket under it that is a non-reusable part.
Diagnostic:
http://www.ncttora.com/fsm/1996/SIL/...fe/cip0115.pdf

Replacement:
http://www.ncttora.com/fsm/1996/SIL/.../ects/comp.pdf

I stick with Toyota OEM for sensors. You want one that looks like this:
http://www.autozone.com/autozone/par...mString=search

J2F42C

Having changed this out on mine just as preventative maintenance, I usually stick with OEM for sensors. I would here, but that is just me.

The gasket under the ECT sensor is brass; if you tighten the new sensor enough (can't remember the torque at the moment but is stated in the FSM), the gasket can be reused.

In order to get to the ECT sensor, the front fuel pipe that connects the injector rails must be removed. There are two gaskets, one for each side between the connector and the rail, that I would replace, and I think are a dealer item only.

Use the search engine here; I wrote about changing the ECT sensor about two years ago in more detail.

Good luck.

legokcen

Thanks for the tips. Since the Scanner was showing the temp changing which correlated to the times the idle was high and it was hard to start it has to be the sensor sending info to the ECU. I'll order one and use the info here to change it.

Again, thanks for the help everyone!

legokcen

I've got it! I was actually surprised at the ease. It took less than 30 minutes start to finish. I used the info above, but didn't fully remove the radiator hose or front cover. If you unbolt the front cover (10mm wrench) and move the radiator clamp back up the hose, you can move the cover back away from the engine enough to give you all the room you need. Also gives you a good view to inspect the timing belt!



The fuel lines take a 17mm wrench and those come off easily. The sensor is a 19mm deep well socket. Simple actually.

The picture below shows the access to the sensor.



Thank you all for your help. I took her for a spin a few minutes ago and the ECT is holding steady and she idles just fine now. Hot start is no longer an issue either.

J2F42C

Good to hear.

That timing belt looks as if it needs some attention as well.

As preventative maintenance for all my autos that are 10+ years in age, I always change out the ECT sensor with a new OEM one. Same goes for O2 sensors.