I talked to a "mechanic" and the phone and told him my S5 is running rich. I told him I thought the temp sensor may be the culprit. He agreed and told me to find the one with 2 wires coming out of it and unplug it and put a jumper between the connectors and see if it leans out. Does this sound right? If so, where do I find this sensor to test it?
Thanks in advance.
Brian

 

Um...

Why don't you download the factory service manual, find the specs for the sensor, and use a multimeter to measure the resistance at various temperatures?

-=Russ=-

 

Well.....I have a dial up connection and my computer keeps locking up trying to open pdf files. I just thought someone nice might have the answer for me and save me the headaches of trying to fix the computer problem too..

 

That's a disturbingly poor test. A direct short accross the sensor is NOT what the ECU expects. I'm not sure exactly how the ECU buffers that signal, but I would be worried about blowing something up if it's shorted directly.

Testing procedures are in the factory service manual, as well as the Haynes manual.

I'm amazed that your "mechanic" suggested this. On many cars, one side of the sensor is either 12V/5V or ground, and the other is the input to the ECU. Shorting either 12V/5V directly to the ECU, or shorting it directly to ground would be a very bad thing.

 

Hey, thanks Aaron, I thought it sounded strange, too. He said the computer would read full hot and lean it out or something to that effect. I really just want to see if the sensor is plugged in at all. I guess I will have to wait until I can get the fsm to download and open right. &%*( dial up!!!

 

alright...I have looked in the fsm and I can see the drawing of the coolant temp. sensor, but I cannot see where it is in relation to the water pump. Is it behind it or something or is that even possible? Help a freakin idiot, please

 

The WATER THERMO SENSOR screws into the back of the water pump housing. The sensor can be read FROM the ECU plug when the plug is disconnected.

Or if this is a series four car, you can back probe pin 2L (green/white) and put the meter on dcvolts with the negative lead to a good ground. When fully HOT the sensor should read approx .4vdc to .5vdc.

Or if you have a wideband to watch, you'll see your afr go from approx 12.3 afr to approx 14whatever afr when starting with a cold engine. It usually takes about 1-2miles for it to go from one to the other. A clear sign that the sensor is working.

 

water temp sensor and water thermosensor are different things. The water temp sensor is right under the oil filter pedestal BUT you are concerned with the water thermosensor sensor located on the back of the waterpump and sends readings to the ECU.

EDIT: he beat me to it

 

So, it would not be something that would be a simple look and see if it is diconnected or if the wires got frayed or whatever....not an easy look and see.

I would have to remove the water pump in other words.


Itis an 89NA
I haven't got an AFR guage, just my nose and burning eyes and puffs of black smoke and 19 mpg hwy.

 

I'd look to see if the GREEN water thermo sensor plug is on or not. You can look from the area of the air pump with a flashlight.

I don't know the ECU pins for a series five. They are online. I'd check the voltage at the ECU myself as described from my upper post. I don't know the wire color or pin number for a series five though. I'd be looking for a figure of .4 volts dc to .5 vdc if the engine is HOT.

I was talking a wideband earlier. A narrow band, well, I don't think it would work using a narrow band.

 

Is it round connector with a "pea" green wire coming out of it? I found it hanging unplugged behind/below the alternator/water pump.

 

Yep, a green injector style connector. It being unplugged is definitly a bad thing.

 

Would it being unplugged affect my gas mileage that much? I had read it in a post somewhere that it does affect mileage, but I can't seem to find it in a search.
Thanks again.

 

Shoulda had twowires coming out of it. You probably forgot to mention the second?

 

Yes, it certainly will. As I recall, the resistance drops as the car warms up. So if it was open, the ECU thought it was mighty cold out...

 

Wait a minute....the connector I found was a round black connecter with only one wire coming out of it....I think I can see the thermosensor is plugged in. Kinda hard to see. Gimme a minute to move the bundle of wire loom outta the way.

 

Well, the thermosensor is plugged in. I got no idea what the other connector hanging there is for. This POS has been hacked on before I got it, so there is no tellin. It has no airpump or 6pi actuators, so I have found a few hanging connectors in that area, but nothing that matches with that round black connector w/green wire.

 

Well, the thermosensor is plugged in. I got no idea what the other connector hanging there is for. This POS has been hacked on before I got it, so there is no tellin. It has no airpump or 6pi actuators, so I have found a few hanging connectors in that area, but nothing that matches with that round black connector w/green wire.

 

did they change the resistance between s5's and s4's? just curious, my car is running really rich and i was thinking this to be the cause of it.

 

The other single wire connector was probably for a electric fan temp sensor that is on some cars.

I'd badger a guess that the series four and series five resistance values are the same for the water thermo sensor.