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View Full Version : Disable cat test on 0411, anyone know how?



mecanicman
07-09-2015, 01:41 AM
shortly after startup when you have the post o2 sensors disconnected the 0411 pcm does a cat test going to 9:1 then 16:1 to look for results. HPT does not offer a way to shut this off, not sure if there is? Wondering if anyone knows if this can be disabled and where I might look?

roughneck427
07-09-2015, 04:07 AM
All I know of is the cat diagnostic over temp. I usually zero out the fuel adder and in check the diagnostic test.

mecanicman
07-09-2015, 05:54 AM
All I know of is the cat diagnostic over temp. I usually zero out the fuel adder and in check the diagnostic test.

There is a master on/off for this in hpt and I zero out the fuel adder as well, does not stop this. Only happens when secondary o2s are taken out, if they are installed with no cats does not happen. Must be a switch for it I just don't know where to look.

Fast355
07-09-2015, 03:46 PM
There is a master on/off for this in hpt and I zero out the fuel adder as well, does not stop this. Only happens when secondary o2s are taken out, if they are installed with no cats does not happen. Must be a switch for it I just don't know where to look.

I will be watching this just in case I tune one without rear o2s or cats someday. Probably has a switch hidden in the code somewhere. Adam aka Dimented24x7 on Thirdgen.org might be able to shine some light on the code aspect of this problem depending on what operating system you are running.

This sounds similar to the old Forced Knock Test of the 7747. The first timing bump was 12* over commanded. If it didn't knock, phase 2 of the test was 22*. If you had an inoperative knock sensor and a hotter engine. Sounded nasty under the hood from all the clattering.