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Bad coolant temp sensor put engine in flood mode????

 
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Old 03 Feb 2012, 06:47 am
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Default Bad coolant temp sensor put engine in flood mode????

My car 2002 PT was cold working fine. Check engine light was on. An Autozone scan said (forget code #) vacuum leak. AutoZone guy said maybe filler door was open. Car ran fine for months with light on. Could not find obvious vacuum leak. I was waiting until springtime to look better.

Back to story. My car 2002 PT was cold and working fine. After driving about a block it suddenlly died. I could start but only with pedal to floor. It would drive as long as I didn't give it gas.

Limped to Sunoco about 1 mile from breakdown area. After 2 days they tell me it is the coolant temp sensor. My temperature gage worked fine. Are there 2 sensors....1 for gage and 1 for brain??? Would this sensor put my car into flood mode???? They also said they could not get any codes. They still have the car. This is going on day 3.5.

Does this sound right??

Thank you.
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Old 03 Feb 2012, 08:09 am
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Default Re: Bad coolant temp sensor put engine in flood mode????

NO, it doesn't sound right and the mechanic at the Sunoco probably doesn't deal with many PT's. Sounds more like a fuel pump problem. The ECT (Engine Coolant Temperature) isn't going to bring the car to a halt. Does he have an OBDII scanner? I think you need one to really find out what your problem is.

Try this, if he's so sure it's the ECT, ask him if he changes the ECT the car will start up and run and if not you don't have to pay for the work.
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Old 03 Feb 2012, 10:15 am
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Default Re: Bad coolant temp sensor put engine in flood mode????

He replaced sensor and says it is all carboned up from running rich. He says he now needs to run it and get the carbon out. Does the ECT sensor control the gage or is that a separate sensor???
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Old 03 Feb 2012, 10:32 am
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Default Re: Bad coolant temp sensor put engine in flood mode????

Ya see, this don't make sense at all. There's no way the ECT will get carboned up. It doesn't come anywhere near anything that can get carbon on it. You or he must be calling the sensor by the WRONG name. The ECT sticks into the coolant right above the thermostat. Where the heck does carbon come into the picture? It must be some other sensor that your talking about like Oxygen sensor or the IAC (Idle Air Controller). Both of those can get fouled up with carbon NOT the ECT.

To answer your other question, The ECT is electronic which sends a signal to the computer. I'm not exactly sure how/where the gauge gets it's input. My guess is from the ECT also.
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Old 03 Feb 2012, 10:52 am
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Default Re: Bad coolant temp sensor put engine in flood mode????

The sensor isn't carboned up. I re-read my post and see why you thought that. I meant my (it) engine (the plugs)...are fouled or carboned up. He tells me there are 2 temp sensors one for the gage and 1 for coolant to ECM. Dealer only sells one.
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Old 03 Feb 2012, 10:55 am
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Default Re: Bad coolant temp sensor put engine in flood mode????

He also said my old sensor only was full on or full off. Sounds like the sensor is a working switch to me. Is the sensor a thermistor or a switch? The schematic I have shows it is variable.
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Old 03 Feb 2012, 11:00 am
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Default Re: Bad coolant temp sensor put engine in flood mode????

IF there are two sensors (and I haven't the faintest idea where the other one is), it would make sense that one is variable to work the gauge from cold to hot and the other is on/off to send a signal to the computer to turn the radiator fan on when it reaches a particular temperature.

One variable sensor could do the same thing. Work the gauge and let the computer know when to turn on the fan.
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Old 03 Feb 2012, 11:23 am
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Default Re: Bad coolant temp sensor put engine in flood mode????

He says the sensor also tells the ECM how much fuel to supply depending if the engine is hot or cold. He says the sensor only shows full cold or full hot. I am assuming it must be stuck in the full cold mode to make the engine run rich. This in turn carboned things up. It all sounds logical to me. I am trying to find out from someone who knows exactly what the ECT sensor's full job is. I know the fan is regulated by the temperature. From what you say the fan gets turn on info from ECM based on the ECT sensor. The temperature gage must also get it's signal from the ECM based on what the ECT sensor says. I can imagine the fuel could also be managed by the ECT sensor.
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Old 03 Feb 2012, 11:31 am
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Default Re: Bad coolant temp sensor put engine in flood mode????

Makes sense when you put it that way. I thought, and still do, that the IAT (Intake Air Temperature) sensor measures the incoming air density to regulate the air/fuel mixture so it doesn't run to rich but I guess the ECT could play a part.
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Old 03 Feb 2012, 12:00 pm
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Default Re: Bad coolant temp sensor put engine in flood mode????

You are right about the IAT. I guess there has to be something that tells the ECM if the engine is hot or cold in order to give it more or less fuel based on those conditions. When the engine is cold it would need more fuel. My engine was cold when this happened. It was probably starting to warm up and the sensor said it was still cold. If the mechanic is right. The temperature of the in-coming air is also a factor.

Also, when you said fuel pump....I also thought that. The thing is, the car starts fine and runs but only in limp condition, maybe 500 RPM.

I haven't asked the guy if he checked the fuel pressure. If he tells me after he cleans the plugs there is still something wrong. 1st I am going to be pretty upset. 2nd when I take it out of there...it will be the first thing I check. Do you have a pic where the schrader valve is? Do you have fuel psi specs? I'll post what happens. If you have more input I'll be glad to listen.

Thanks for your input.

Last edited by ptcruiserjim; 03 Feb 2012 at 12:04 pm.
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