2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

water thermosensor question

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Old Dec 28, 2005 | 08:35 PM
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water thermosensor question

ok so i'm trying to troubleshoot my car's issues...
it will only start occasionaly. it will start at about 1500 rpm when being towed. it sometimes smokes a hell of a lot of greyish whiteish smoke and the stock cat. converters glow very very red. i think it is flooding, i smell fuel. i've tryed removeing the egi fuse, flooring it while cranking, pulling the plugs, testing spark, shanging wires, setting timming, checking fuel press. ect. This is a rebuilt engine and has ran like this since i put it in. i have done a compression test and it is fine. it generally won't die while driving but missis and runs generally crappy. it will always die after ideling for a few minutes. the engine has less that an hour and five miles of run time.
tomarrow i plan on taking the fuel injectors out and trying to test them and swiching the pirmarys with the secondaries.
i've read on here that the water thermosensor can cause very rich running which is why i am trying to figure out more about it before i take it apart tomarrow. is there a way around the thermosensor by grounding one the plug of shorting it somehow? should there be a voltage at the plug that i could check, or something on the sensor that i could test? just to clarify, we are taking about the green connector on the back of the water pump.
I'm just assuming that the car is running way to rich.... could very lean running cause the cat's to glow red?
BTW: its a 19' N/A
thanks for any help,
Philip
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Old Dec 28, 2005 | 09:45 PM
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any ideas on if the water thermosensor could cause running this rich?
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Old Dec 28, 2005 | 11:34 PM
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The thermosensor is a variable resistor that steps down a voltage at certain temperatures and feeds the information to the ECU. If the sensor is malfunctioning, the ECU defaults to a certain temperature (NZConvertible knows the exact #). Your car WILL run with the sensor in default mode. Sounds to me like you may have other issues. Greyish/white smoke is not an indicator of running rich, thats more like water getting into the chambers. Also might try a compression check to see if the motor is still healthy.

You CAN do a check of the thermosensor as per the FSM. This involves a thermometer, a Multimeter, and the sensor.
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Old Dec 29, 2005 | 09:15 AM
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Originally Posted by J-Rat
The thermosensor is a variable resistor that steps down a voltage at certain temperatures and feeds the information to the ECU. If the sensor is malfunctioning, the ECU defaults to a certain temperature (NZConvertible knows the exact #). Your car WILL run with the sensor in default mode. Sounds to me like you may have other issues. Greyish/white smoke is not an indicator of running rich, thats more like water getting into the chambers. Also might try a compression check to see if the motor is still healthy.

You CAN do a check of the thermosensor as per the FSM. This involves a thermometer, a Multimeter, and the sensor.
yeah thats what i've heard about the smoke being coolant BUT would whater leaking into the chambers cause the cats to glow RED hot? i thought water would just make steam ect. maybe cool down the cats if anything.... i don't know though.
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Old Dec 29, 2005 | 12:48 PM
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The water MAY be releasing more oxygen and causing the catylist reaction to increase. This is PURELY a theory though, I have NO proof of this ever happening.
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Old Dec 30, 2005 | 09:03 AM
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Originally Posted by J-Rat
The water MAY be releasing more oxygen and causing the catylist reaction to increase. This is PURELY a theory though, I have NO proof of this ever happening.
any other opinion on this^?
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Old Dec 30, 2005 | 09:12 AM
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A red-hot catalytic converter "usually" means raw excess fuel ... litterally burning the cat substrate and leading to very high temperatutes within the cat, thus the red hot glowing look. That's well documented.

I doubt steam would do it (unless proven otherwise )
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Old Dec 30, 2005 | 01:06 PM
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ok, so it must be the fuel injectors....
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Old Dec 30, 2005 | 02:02 PM
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FYI,

Clogged cats will glow red also.
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Old Dec 30, 2005 | 02:16 PM
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this is a good thought, i was,nt sure if that would happen..... would clogged cats cause a lot of smoke to come out of the cat and not the exauhst? lots of hot air (exauhst fumes) comes out of the pipe but lots of smoke comes from the cat area.
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Old Dec 30, 2005 | 02:22 PM
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if you suspect the exhaust is clogged, you can remove the oxygen sensor and see if it runs any better. It opens up the exhaust just a tad for diagnosing purposes.

Also, a clogged exhaust creates quite a bit of backpressure and you may be able to diagnose it with a vacuum gauge. On a piston engine, the vacuum would drop at idle if clogged. To be verified on a rotary though

also, if you have a clogged exhaust, you don't have much power. that's another way to tell.

note that you could have several problems going on at the same time if there is also white smoke coming out the exhaust.

Last edited by hugues; Dec 30, 2005 at 02:42 PM.
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