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-   -   Montero engine runs but dies when warmed up (https://mitsubishiforum.com/forum/mitsubishi-montero-montero-sport-14/montero-engine-runs-but-dies-when-warmed-up-51835/)

montey cosmopolitan 02-18-2018 04:43 PM

Montero engine runs but dies when warmed up
 
I have a 99 Montero sport v6 that for some reason when I was driving all of a sudden the engine died ... I was low on gas so I got a can and put some in .... The motor started and it drove me about a quarter mile and died again ... Thought I needed more gas so poured more in and same thing ....
finally got home and put neighbors code reader on and got the

P0335

I've checked the sensor and it's reading fine plus it wouldn't start at attached it the crankshaft sensor was failing .... Is there any other reason why my engine would fail when warmed up ?

When I clear the code and start it again it tells me 0 codes

Thank you for any and all assistance

HunterD 02-18-2018 06:02 PM

It is possible that the sensor is failing. It may have good signal when cold, but once the engine (and sensor) warms up, you get a bad/intermittent signal due to poor contact or a break in the wire. You can start by disconnecting the sensor, cleaning/fixing the contact points. If you you're able, put a voltmeter on the sensor start the engine and monitor the reading to see if you will start loosing voltage on it.

montey cosmopolitan 02-20-2018 04:36 PM


Originally Posted by HunterD (Post 323013)
It is possible that the sensor is failing. It may have good signal when cold, but once the engine (and sensor) warms up, you get a bad/intermittent signal due to poor contact or a break in the wire. You can start by disconnecting the sensor, cleaning/fixing the contact points. If you you're able, put a voltmeter on the sensor start the engine and monitor the reading to see if you will start loosing voltage on it.

I'm all set up for checking the sensor .... Other instructors say I should crank the engine by hand and I should get an on/off reading of 5:volts

What should my voltage read if I connect to the blue wire and diminish to ?

HunterD 02-20-2018 05:11 PM

The reference voltage is 5v. Withe engine rotated by hand, the signal will pulse 5v-0v-5v-... IT may not be 0v, but will be low. The problem is - this method will let you see if you get a signal at every 120 degrees of engine rotation. The engine dying issue occurs when engine is warm. I don't know if you will be able to see the malfunction with the engine warmed up and rotating engine slowly by hand. You may need warm up the engine, backprobe the plug connector further away from the sensor, get to where you have 5v signal and wiggle the wires to see if you can induce the loss of signal. That may show a bad/broken connection once the things get up to operating temperature.

montey cosmopolitan 02-21-2018 03:16 AM

I used a pin to stab through the wire and connected my multimeter to it and ran the motor ...
it showed me a steady 2.1 v
That was running cold
In the morning I plan on doing the test again ... The motor seems to still run after it warms up if im just letting it sit and idle so tomorrow I have to psych myself to be ready to pull the front of the engine off and replace it ...nlol

HunterD 02-21-2018 10:58 AM

the 2.1v reading might be due to the fact that multimeter can't refresh fast enough, so it gives you an average reading of high and low. It is very much possible that the issue is in the wiring harness and not in the sensor itself. Would be good to back probe the sensor contact at the PCM, run engine at operating temperature and monitor voltage there. Wiggle all parts of the harness and see if you loose signal at some point. I'm leaning more toward the wiring being at fault rather than a sensor itself.

montey cosmopolitan 02-21-2018 03:22 PM

What and where is the PCM ?
can a short in the harness be temperature sensitive ?
While driving I would get my door open light to start comming on and at speed of 50+ mph would stay lit until I stopped or slowed down .... I'm not very good with wiring

montey cosmopolitan 02-21-2018 05:13 PM

I started pulling front of motor or and checked crankshaft sensor again by hand ... 5.009 volts ... But not at temperature .... Code reader says
P0335
Would the code reader be able to read past the crankshaft sensor and pick up the cam sensor if it was bad ?

HunterD 02-22-2018 11:16 AM


Originally Posted by montey cosmopolitan (Post 323050)
What and where is the PCM ?
can a short in the harness be temperature sensitive ?
While driving I would get my door open light to start comming on and at speed of 50+ mph would stay lit until I stopped or slowed down .... I'm not very good with wiring

PCM = Power Control Module, i.e. car's computer brain. It is usually located under the dashboard, on passenger side.
Yes, the short or break in the wire can be temperature sensitive. When materials heat up, they expand and that may move things around so that you loose contact. That is kind of what I suspect. It can be a break in the wire harness, or a bad terminal at some connector. Having a symptoms like you describe with the door is a confirmation that you have some issues with old wiring. The engine harness and the body harness (doors, dome lights) are likely be separate (or at least different parts of one large harness), but it is sort of confirms that wiring is what you are likely dealing with. There is not fast and easy way to do it. What you need is methodical checking of all wiring from the sensor all the way to PCM (computer)


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