Cat Over temp (COT)
Thread Starter
Instructor
Joined: Jun 2009
Posts: 165
Likes: 4
Cat Over temp (COT)
Is it normal for COT to activate at highway speeds? I know on the dyno COT would activate and drop my a/f to 10.9. But its also activating when i do WOT runs on the highway. Any thoughts on this?
Thread Starter
Instructor
Joined: Jun 2009
Posts: 165
Likes: 4
. that means half way down the track I am seeing 12.5-12.8 and the last half i am seeing 10.9-11.1. This does not sound right!
Pro
Joined: Feb 2003
Posts: 745
Likes: 136
From: Detroit MI
I have the stock exhaust and a Halltech Venom intake. Once the O2 sensor reads 1500deg F, my a/f goes to 10.9-11.1... I did a few more pulls today and it only takes about 5 seconds to get from 1250deg F to 1500 deg F on a WOT run... . that means half way down the track I am seeing 12.5-12.8 and the last half i am seeing 10.9-11.1. This does not sound right!
. that means half way down the track I am seeing 12.5-12.8 and the last half i am seeing 10.9-11.1. This does not sound right!
Thread Starter
Instructor
Joined: Jun 2009
Posts: 165
Likes: 4
It sounds like your PCM calibration is not accurate for your new intake/MAF housing. You are most likely feeding the PCM a bogus MAF number, which is a primary input to the Cat Temp model. If you fix the tune's fundamentals (MAF curve), you'll find that Cat Overtemp fixes itself.
