Question for you Chev guys... about an Exhaust temp sensor 2011 Diesels

[F_ast]

Hey guys,

I blew the exhaust temp sensor on my Xfire last week an in need are another. I refuse to pay AC $175 for a new one, so I have been looking around for a suitable replacement.

I have found that the new 2011 diesels use pretty much the exact same temp sensors found on the cats. I was wondering if someone knows or can find what the operating resistance on this sensor is.

Cat specs the operating resistance on the their at 250ohms (room temp) to max of 950ohms. Is anyone able to recover this info from the chev ones? I have 2 of these on order from the states for $20 each, so it is worth a shot.

Part numbers I have for the same item are 12636945, 12639455, 213-4759 and the Chev dealer today told me the newest number for these is 12643246

Thanks.

 

[Jeff K]

Do you know for a fact the sensor is blown? It is quite common for the wires near the connector to get pinched and break. Seen this more than a couple time. Just something to check.

 

[TheBreeze]

I had a pipe temp sensor failure. Found the wire rubbed through on the EGT wires. 2 seconds and 2 inches of electrical tape fixed it right up.

 

[WyoBoy1000]

I noticed the similarity as well, but if you get the latest part numbers for each and they don't match, I dont think it will work. The diesel industry has much higher epa standards than just about anything. My guess is the chev sensor need to read temps of 2000* where the AC ones are prob closer to 1000*. But let us know if you figure it out. I wish I could just over ride the sensor with a set temp and then map it myself with my own egts and fuel controller.

 

[F_ast]

I noticed the similarity as well, but if you get the latest part numbers for each and they don't match, I dont think it will work. The diesel industry has much higher epa standards than just about anything. My guess is the chev sensor need to read temps of 2000* where the AC ones are prob closer to 1000*. But let us know if you figure it out. I wish I could just over ride the sensor with a set temp and then map it myself with my own egts and fuel controller.

You can. The temp sensors output is just a signal; That control signal is ohms. Room temp resistance on the cat sensor is roughly 250ohms on multi meter. If you heat the sensor with a heat gun, the resistance of the sensor increase all the way up to about 950ohms. You can simply over ride this to a set point by cutting out the prob and putting a resistor in place. I have a 1/2watt 680 ohm resistor that I am going to try, but am looking to try this sensor first. The difference in the sensors is most likely going to differ, if anything, by the bimetalic strip on the inside of the probe. That why I has hoping someone would be able to tell me the working resistance of the Chev sensor.

Is someone able to read the resistance on a room temp sensor and a heated sensor? A mechanics diagnostic procedure should list this info as well.

As for my Cat sensor, I have looked over the wires carefully and have no rub marks, wear marks of any kind. I have also pulled the plug apart to see if the leads came apart from the pins. They were fine. I have not pulled back the rubber wire casing, but is it possible for a wire inside to just break?

The sensor right now reads 0ohms.

 

[WyoBoy1000]

I know you can put in a sensor, but if the computer is programmed to read variations it wont work because it will only see a constant, I came across this problem eliminating the secondary sensor on a 98 chev 350, when I cut out the cat, I wound up installing the sensor at the back of the manifold and then putting in a resistor and it was just enough of a heat change that is fooled it to working. So it will all depend on what the ecu needs to know, also i don't know how these sleds are mapped but it could effect timing, But the biggest problem is at 6000rpm, this is where AC is trying to hit the epa standards and it leans out the system, so if the ecu thinks its not getting hot enough it will keep cutting fuel until it burns down or dies. This is also why when people add mods you can't run a steady throttle, and if you try to add fuel with a say a bd box at this rpm you can add as much as you want and the ecu will just keep cutting the fuel back and then when you get on it it will fall on its face.

All the time you spend trying to do something cheap, I have found its cheaper to just buy the part and spend all that time doing something that pays, usually I could have bought 2 or more if I was getting paid by the hr trying to figure it out.

 

[F_ast]

I understand that the ecu will obviously be reading the exhaust gas temp, and be calibrating the ecu, but if you were to trick it with a resistor in the in the mid opt temp range, would you not suspect that the fuel delivery would be optimal? I get that gas that is too hot is an indication of lean condition, but would the knock sensor not detect this also?

What is the prime function of the stock EGT prob?

 

[jakey-boy]

All that sensor does is tell's the ECU when the sled is warmed up enough that it will let it run properly. As long as it is above that point then sensor is doing nothing. It's an all or nothing deal. Put a resistor in mine and it works perfect. Just make sure you let the sled warm up really well before you go racing on it because the sled will be running closer to the breaking point then it should during a warmup.

 

[WyoBoy1000]

I disagree completely, If so then why can I add 20+ points across the board at 6000 rpm and it will always go lean, I have even done this with my fuel pressure cranked to 51psi, thats a ton of fuel. You may have made yours work but I would rather have the benefit of knowing its right, also how do you think emissions are hit, with fuel air and correct timing, timing can play a huge role and if you have it set one way there may be other factors to change timing but you may not be getting the full advantage. With that said you may also be pushing it a little harder and getting better performance, I wont do it without knowing all the functions for a fact. Just my opinion, but unless you are the guy from AC that mapped these sleds I'm not going to buy it.

 

[F_ast]

Got a hold of someone who gave me the perameter for the Chev temp sensor. I have to verify the numbers correlate with cats, but I believe they are close.

Does anyone have the test or trouble shoot proceedure that lists the ohms to temp chart?

Chev 2011 Diesel Exh. temp sensor (12643246)
Temp(F).....Ohm(approx)
1832..........849
1652..........795
1472..........738
1292..........680
1112..........618
932............554
842............521
752............488
662............455
572............420
482............385
392............349
302............313
212............276
122............238
77..............220
32..............200
-4..............185
-40.............170

FYI: Removed the wire shield from the cat sensor today from connector to the probe. No broken wire in there.

 

[grandpaj]

O Ohms

If your pipe sensor reads 0 ohms and the wires are not shorted together somewhere it is bad. The official arctic cat book says if it reads o or infinity or open then it is bad. Hope this helps.

 

[F_ast]

Awesome news for anyone who does not want to spend $150 on a new Exh. temp sensor. This parts resistance matched up exactly. Cat temp specs to chev temp specs.

Picked up these for $20 ea. on ebay.

2nd and 3rd column is resistance in ohms

 

[JHG]

Nice work man.....