CAM and crank shaft position sensors

MELVIN SANDVLIET

MEMBER
1997 MITSUBISHI ECLIPSE
2.0L
4 CYL
2WD
AUTOMATIC
97,000 MILES

Hello I have the GS model 2.0/4 cylinder 16 valve dual overhead cam non turbo.
I bought the car non running was told that on the way home from work while in motion the car just shut off and never started again they said there was no power surge or loss, no motor stumble. It was as if the key was just shut off and car just rolled to a stop and had to be towed home that is all I know. So far I replaced the fuel pump, fuel filter checked and cleaned the injectors cleaned the EGR valve changed the plugs and checked the ignition coil pack and plug wire's they are good. Only thing I can think of is cam or crank shaft position sensors. My question is, how many of each does this particular model have and where are they located at on the vehicle? If you can shed some light on this that would be extremely helpful and appreciated. Also, if I missed something else perhaps I should have checked any advice would be also gratefully appreciated and welcome. Thank you. Although I have to add I also spray starter fluid into the throttle body in the vehicle the vehicle seems as if it wants to start runs for about two seconds then backfires and shuts off. Not sure if this is relative to anything but just giving as much information as I can.

3 Replies

STEVE W.

MECHANIC
13,480 POSTS

That description sounds more like it jumped timing on the cams. I would verify the timing there first. Then do a compression test to see if it is high enough, you want to see at least 175 psi in each cylinder.
As for the sensors, the crank sensor is directly above the oil filter and goes into the side of the block. The cam sensor is on the drivers side of the engine and goes into the head and reads the target magnet on the cam.

You mention that it runs for two seconds then shuts off, does it do that every time you try to start it? If yes then your problem could be in the immobilizer system. A failed component or being triggered on will shut the engine down after two three seconds. Coupled with it not being run for a time and it would act the way you describe.

I would try the compression test, then connect a spark checker to it and see if the spark shuts off as it shuts down. If you lose spark it is likely the immobilizer.

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Friday, February 8th, 2019 AT 6:45 PM

MELVIN SANDVLIET

MEMBER
2 POSTS

I really appreciate your help and I also had a sneaking suspicion it may have been the immobilizer. However, the car is not chipped I don't know if that matters seeing how I don't know what year they started implementing immobilizers to begin with. But I was under the impression the car has to have a chip in it located in the key that reads as soon as you put it in the ignition. But I have been wrong before. Also, not sure if I mentioned this before probably should have if I didn't the car is not throwing any code whatsoever. I don't know if that changes anything but I figured it couldn't hurt to let you know that. I'll check the compression as soon as I buy a compression test kit unless there is some DIY way of doing this without having to purchase a kit. One last thing, there is a aftermarket alarm on the car could that possibly interfere with the immobilizer that you mentioned earlier? I really hope not because I didn't get the key fob that comes with it. It came with the unit that they installed. Would you suggest completely removing the entire alarm system?

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Friday, February 8th, 2019 AT 7:20 PM

STEVE W.

MECHANIC
13,480 POSTS

Well first I would look at the way that alarm is connected and probably remove it. They can cause a bunch of problems depending on how they were installed and most do have an engine shut down function. It should have a model number somewhere on it that you can look up and get the install directions. That way you don't miss the one wire they added or cut to cause your problem.
For the compression test, many of the chain stores have loaner tools, basically they "sell" you the tool, when you return it you get your money back. However in light of the alarm, check the spark first. If it is being shut off it could easily be the alarm.
As for codes, most of the time a bad crank sensor won't set a code, unless it is an intermittent one.

There are various anti-theft systems. The factory system for your car shuts off the power to the ignition and starter. It is armed using a remote that controls the locks. There are a couple relays in the relay box behind the dash if it has the OEM unit.

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