nox reading way high

[bears4x4]

ok its about my wifes 92 carmaro, its a 305 i have replaced everything on it but the o2 sensor, would that effect this??

all electrical on motor, head, intake, throtle body gaskets etc, every thing but this "i did the top end"

 

[JLDickmon]

ok its about my wifes 92 carmaro, its a 305 i have replaced everything on it but the o2 sensor, would that effect this??

all electrical on motor, head, intake, throtle body gaskets etc, every thing but this "i did the top end"

high NOX on a gas engine is a function of combustion temperature

timing over-advanced (you did unplug the timing connector, right?)
thermostat too high of a temp,
egr malfunction (as in NOT)

'bout all I can think of at the moment..

 

[Zookie400]

heat heat heat like JL said.

something is causing high combustion temps, lean mixture, egr system failure, t-stat.

cool it down in there, or cheat with alcohol!

 

[bears4x4]

all new, map sen, egr.i put a 185-190 thermosat in it, factory said like 165, i was going for a lil warmer- better fuel milege, ill change it back any other ideas let me know

 

[JLDickmon]

heat heat heat like JL said.

something is causing high combustion temps, lean mixture, egr system failure, t-stat.

cool it down in there, or cheat with alcohol!

yeah.. lean mix... throw a fuel filter on it while you're at it.. does it have a good idle flare when you start it?

 

[BJS]

o2 sensor could be the culprit causing poor fuel mixture resulting in high cylinder temps.

 

[bears4x4]

yeah.. lean mix... throw a fuel filter on it while you're at it.. does it have a good idle flare when you start it?

im doing the o2 sensor, fuel filter, tomorrow, its the only things i can think of that i havent done in a while

 

[JLDickmon]

im doing the o2 sensor, fuel filter, tomorrow, its the only things i can think of that i havent done in a while

If you have an O2 forcing a lean enough condition to drive the NOx high, you're going to set a code..

did you propane it to check for vacuum leaks?

 

[bears4x4]

If you have an O2 forcing a lean enough condition to drive the NOx high, you're going to set a code..

did you propane it to check for vacuum leaks?

what do you mean propane it to check for leaks, never heard of that?

 

[DaveBen]

You spray propane around the suspected leaking vacuum hose, and if the rpms increase, that is the leak. Fuel will cause the motor to increase in rpms, Old trick...

Dave