Okay.. i'd like to know what sort of operating temp the catalytic converter on our cars should be running at.

I have my carpc monitoring the stock cat temp sensor and I'm consistently seeing temps over 1600f+! I've had times when it has jumped up to nearly 1800f!

Is this indicative of a clogged cat? A weird question, but would this affect gas mileage? Anything else I can look for?

I tried to point this out to the dealer last time I was there and they threatened to void my 'engine warranty' for using the obd2 port to monitor this stuff. ********.

 

who threatened you that ?

rofl, how does monitor stuff effect the engine in any way ? the port is there for a reason.

 

dealers are stupid. Curious about this as well.

 

I've never monitored my own 8 to see where it runs, but those numbers don't seem too alarming to me. I would expect the temp to hit 1800 running it hard for an extended duration of time, and 1400-1600 for most "normal" driving situations (possibly much lower when cruising on the highway). I'm not sure what the optimal operating range for the OE cat is, but I think it can tolerate temperatures like this without failing catastrophically.

 

The general rule of thumb is that the temperature after the cat should be ~200 degrees cooler than temperature before the cat.

From a site I found:

Quote:

The average light off temperature at which the catalytic converter begins to function ranges from 400 to 600 degrees F. The normal operating temperature can range up to 1,200 to 1,600 degrees F. But as the amount of pollutants in the exhaust go up, so does the converter's operating temperature. If the temperature gets up around 2,000 degrees F or higher, several things happen. The aluminum oxide honeycomb begins to degrade and weaken. The platinum and palladium coating on the honeycomb also starts to melt and sink into the ceramic substrate reducing its effect on the exhaust. This accelerates the aging process and causes the converter to lose efficiency.

 

clogged cat=horrible gas mileage I would definetly think is probable

 

OP - go back to your dealership and punch them in the back of the head.

 

wow. voiding engine warranty because your plugging into your obd II? lol!!

 

1600 with an obd2 sensor is really the norm.

on cruise the cat hits 75mph. and the fuel gets added to save the cat.. it drops the cat temps down to. 1609.

beers

 

where are they taking the temp from? Mine is FI and I run at rest 900, driving highway 1100 and hard 1400-1500. At the last temp the motor feels like its going to give. I would like a methanol kit to run things somewhat cooler. My sensor is a little after the manifold.

 

The thing is they believed that my carpc in the trunk was a "aftermarket ecu". Believe me when he said that he would void my engine warranty I laughed and said "yeah.. okay!". The service writer was Mike. This dealer is one of the more reputable dealers in my area, I have 3 other dealers within 10 miles of me. I am in NYC, yet I chose to pay a toll and go 25 miles out to Wayne Mazda because they take good care of a lot of our local cars. That and their head rotary technician is a member on these boards and he's cool with us.

Back on topic though.

At my cruising speed on the highway of 75-80 I consistently see mid 1600s F on the cat temp.

How would a midpipe affect the "cat saving" function of the ECU where it dumps fuel to conserve CAT life?

 

I wonder what did you tell him about your car PC after Mike said its aftermarket ecu.

Cuz its not.

but still they can still void your warranty cuz its link up to the electrical system.

its easy to kill ur cat actually.

Start ur car and shut it down cold. wait 20 minutes. Do the Mazda de-flood thing. repeat these steps couple of times, Fire your car up. Ur cat will be dead in no time. Trust me it works (so u get a new cat)