I've tried this one every which way.. Even my mechanic can't figure it out and his only solution is to start randomly replacing different parts til the problem resolves. Way too expensive route imo.

So heres the actual problem: 1997 Mit Montero Sport 4cyl 2wd Standard
Starts cold with no problems. After reaching normal running temperatures, if you turn it off, it will not restart for between 10-30min. Cranks and cranks like a beast, just will not turn over. Once its temp has dropped to roughly half of normal running temp it will finally start and carry it on its merry little way like nothing happens.
Battery, Starter, Distributor all test normal. Ignitions system does not appear to be the culprit. When hooked to the tester the only error code given is p0115 Engine Coolant Temp Circuit.
To the best of my knowledge, this engine doesn't (and has never) run hot. No coolant loss, no boiling water, no debris in coolant.
Any ideas? Suggestions? Where do I start?
Any help be greatly appreciated!
TYVM,
Michele

 

You have a sensor that the ECU uses to map fuel that is bad. I think it is a different sensor than the temp gauge one. I googled the code and this is what it spit out.
From what I can find, there are two sensors. The sensor with 2 electrical connectors is the one that might be bad. The sensor with one connection is for the temp gauge. They are not expensive at all and should be easy to replace.

Rob

 

Any idea where that sensor might be located? Or the name of the sensor so I can locate it in the repair manual?

 

I think Obakemono hit it right on the head. I haven't had any experience with that sensor but some more googling came up with the links below that may help. It's called the Engine Coolant Temperature Sensor, sometimes ECT. As noted in the links, one symptom is hard starting. As Obakemono said, this is not the temp sensor that drives the temp gauge but they should be located very close to each other. The third link below has a location diagram for a Montero V6 that might give you a clue on your 4CYL. Should be near where the top radiator hose connects.

Again as Obakemono said, the one you're looking for should have two wires while the gauge sender will have one. If all esle fails go to a NAPA auto parts store or dealer parts dept and once you see the unit you (or the store clerk) may be able to find it on your truck. Once replaced, have your check engine light reset and you should be good to go. Ron

http://www.obd-codes.com/p0115

http://www.wiringdiagrams21.com/2010...ircuit-diagram

https://mitsubishiforum.com/forum/sh...erature+Sensor

 

From what I could see in PDF's of the engine repair manuals, they are both within 3 inches of each other on the left side of the engine, on the intake manifold (maybe) or near the thermostat housing. Look for brass colored bolts with the wires attached to them.
The sensor is probably out of spec, meaning when it is cold it is reading 1/2 warm and when the engine is at operating temp the sensor thinks it is way too hot, thus throwing off the ECU, then the ECU messes with the fuel and you get the hard starting. Has your fuel mileage been off? Anyway, the part should be about 15-30.oo max and all you would need to do is replace the sensor and wrap some teflon tape (Home depot, plumbing section, about a 1.00 for a roll) on the threads for sealing. Have a friend help you if you need it.

 

Here's another link with a good photo of what the sensor should look like (similar) and an interesting DIY video.

http://www.obd-codes.com/faq/ect-sensor.php


Ron

 

Nice vid to help out.

 

Thanks!

But did you notice the video expert is all wrong about leaving the end part bare to "get a good ground". As you pointed out, teflon tape is better for liquids than his suggested silicone sealant and this sensor needs no ground -one of the two wires is the ground. I think he got the installation confused with the gauge sensor which has only one wire and has to have metal to metal contact.

Cheers,

Ron

 

Awesome info! Thanks so much! I'll give this a whack today and see how things turn out and update later

 

dragonflysea did you ever fix this problem? I have a '97 Montero SR 3.5L V6 and had the same/similar problem a couple of years ago. I fixed my problem by just cleaning and sanding down the battery terminals thoroughly and then I sprayed some WD-40 on them. Haven't had the problem since. Make sure you put them back tightly but be careful; too much and you'll strip the nuts/bolts.

If you see a lot of the white powder on your battery terminals then that might be it. It's worth a shot.

Good luck!
xp