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-   -   crankshaft position sensor use (https://www.mx6.com/forums/2g-mx6-general/282136-crankshaft-position-sensor-use.html)

Goodbar 2-21-19 15:14

crankshaft position sensor use
 
On the MX6, is it used only to detect misfire, or is it also used for spark timing ? If it is used for spark timing,
then failure of the sensor can prevent the car from starting at all.

I would like to know this. I parked the car one evening. Next morning it turns over fine, but no hint of starting.
The 02 code light is on, meaning something is wrong with the crankshaft position sensor, or wiring, or engine. If it is only used for engine misfire in our cars, then the car should start.....and I would know the car is not starting because of some other issue besides the crankshaft position sensor light.

NickR 2-21-19 19:14

It's used for spark timing, I think. But it depends on the year of your car. If your MX6 is a 93 or 04 it will use the NE1 sensor (in the distributor) if code 02 is present, and will still run (though not as well). But a 95 or later car does not have a NE1 sensor, and will not run when code 02 is present.

First check the connector to the crank position sensor (down behind the oil dipstick). It's a known weak spot, because water gets in there.

The crank position sensor should have between 520 to 580 ohms resistance.

Goodbar 2-21-19 19:25

Thanks, it was raining that day when I parked it, so hopefully just the sensor has gone bad. It is a 2.5 l v6 engine off
a Millenia, about year 2000. It is turning over well, but not even a hint of starting.

NickR 2-21-19 19:45

It's used for spark timing, I think. But it depends on the year of your car. If your MX6 is a 93 or 04 it will use the NE1 sensor (in the distributor) if code 02 is present, and will still run (though not as well). But a 95 or later car does not have a NE1 sensor, and will not run when code 02 is present.

First check the connector to the crank position sensor (down behind the oil dipstick). It's a known weak spot, because water gets in there.

The crank position sensor should have between 520 to 580 ohms resistance.

NickR 2-21-19 19:46

Apologies for double post. Computer messup.

Goodbar 2-22-19 15:01

I replaced the crankshaft position sensor. Here is what I am getting now:

- engine turns over, no hint of starting
- cleared all cel codes, now don't have any - before, I got the 02 code NE2 crankshaft position sensor
- I put the timing light on sparkplug #1 wire, to see if it flashed when turning over the engine - no flash, so no spark
- odd new thing is when in diagnostic mode, both cooling fans come on, that did not happen before

Any ideas what to do next, please post. Looking like something with the distributor. But why would that happen overnight, as it was running perfect the day before

NickR 2-22-19 21:54

In diagnostic mode, the cooling fans are supposed to be off with the throttle closed, but both cooling fans are supposed to come on at high speed when you open the throttle ever so slightly. (This is known as the "fan method" for adjusting the throttle position sensor.) I think it's some sort of "fail safe" mode to prevent overheating if the ecu is not getting a proper reading of temperature. But I doubt that is related to the no spark problem.

I would suspect the distributor, because it's a known weak spot. But I'm just guessing. (I suppose you have checked the timing belt has not broken, and that the distributor rotor is turning?)

Goodbar 2-23-19 10:50

Quote:

Originally Posted by NickR (Post 2651536)
In diagnostic mode, the cooling fans are supposed to be off with the throttle closed, but both cooling fans are supposed to come on at high speed when you open the throttle ever so slightly. (This is known as the "fan method" for adjusting the throttle position sensor.) I think it's some sort of "fail safe" mode to prevent overheating if the ecu is not getting a proper reading of temperature. But I doubt that is related to the no spark problem.

I would suspect the distributor, because it's a known weak spot. But I'm just guessing. (I suppose you have checked the timing belt has not broken, and that the distributor rotor is turning?)

There is a lot of moisture condensation on the runners and some of the plastic parts. I haven't taken off the distributor cap yet, to see if there is moisture inside. Will do that today. I don't see any condensation on the outside of the distributor cap or wires. This distributor only has about 4,000 miles on it.

I doubt the timing belt just broke when I stopped and parked it overnight. I know they can fail at unusual times. If I see the distributor rotor moving, I will know if the timing belt is still in 1 piece.

Is the use of the timing light a good way to test for spark ?

NickR 2-23-19 12:35

I don't know whether using a timing light is a good way to test for spark. I would do it the old-fashioned way, as a check, just to be sure.

Goodbar 2-23-19 14:23

I checked for spark by putting a spark plug attached to a spark plug wire next to metal on the engine - no spark.
I took off the distributor cap - dry inside, everything looks normal - rotor turns like normal.
I could be stumped - I don't have the sophisticated electric meters or tools.
Weird that I just park it after driving all day, next day nothing except engine turning over.

NickR 2-23-19 15:43

I'm stumped too. It wouldn't be the first time a distributor has died for no apparent reason (I killed mine by cranking the engine with spark plugs disconnected to test compression, which would have been fine on any other car).

I would double-check the connectors to the distributor are plugged in tight. Then, if it were my car, I think I would replace the disty, simply because I can't think of anything else.

Goodbar 2-24-19 12:55

I was able to get a test light, light up from the 3 prong primary connector, so power must be getting to the distributor. I ordered a new one and will put that in and hopefully the car will start. If so, it won't explain why it failed with only a year and 4,000 miles on it. There was a lot of moisture the day before, so if the new distributor works, chalk it off to moisture getting in the previous distributor. One time before I got water on the alternator from driving through high water - it failed the next day.

One unusual thing about my car setup is I have a 1994 MX6 which had a v6 engine. I put in a Millenia engine from a car around year 2000. So the newer model distributor that would go on the Millenia engine does not necessarily work with the wiring from the 1994. At least that is what the books show, as they show different test methods for power. When I first put in the Millenia engine with the distributor that came with it, it did not start. When the older style (newly purchased) was put it, the car started and ran fine. The older style is what is installed now, and the older style is what I purchased.

NickR 2-24-19 20:52

I remember reading that it's possible to swap newer for older distributors, provided you swap the positions of 2 of the wires that go to that 3 wire connector. But I can't remember which ones.

I've got a 94 too. I hope replacing the disty fixes the problem. And I hope you stick around this board, because you know stuff, there's so few of us left nowadays. There used to be such a big MX6/626/Probe community, but ProbeTalk.com is dead, and 626.net is very quiet.

Goodbar 3-1-19 14:28

Thankfully it was the distributor. Looking at everything, now I am guessing water came in when I parked. All we have for parking is aluminum roof covers. It looks to me like water came down from openings in the roof, and I likely was parked right where the water came down. There was too much condensation around the engine to guess otherwise.

After installing the car started, and after timing correctly, the engine runs good at idle. However, now there is some lack of power until about 2500 rpm, then it may surge - almost like it is in limp mode. But no codes, and nothing else I can see. A small backfire at 3000 rpm. I am thinking the egr emissions equipment is causing it. I did get a code 29 shortly after starting with the new distributor, but now it has gone away. No codes at all now.

Goodbar 3-1-19 23:35

Now got the car running nice and smooth. Found a few things:

- the egr vent solenoid valve was no good. I had a replacement from a harvest at a junkyard a few years ago, so quickly fixed that
- the throttle cable rubber had lost its anchor, and not staying put on the steel bracket when the throttle was pulled
- the crankshaft position sensor wires were incorrect. I have no connector on the 3 wires coming from the wire harness, so have to put each wire in the cpk by hand. I had put them in to match up the wire colors coming from the cpk, but that was not correct. The manual shows the green and blue wires on the outside, but doesn't show a 3rd red wire. Once I put the wires in this way, with the red in the middle, engine power returned like normal, and once I adjusted the idle screw, everything was good.


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