Failed Colorado Emissions - NOx - FJ80 1994 (1 Viewer)

[runned1]

Update: I got new cats, have been running quality fuel, and i failed emissions again for nox. i know its the egr system. But the fxxxed up thing is that the pipe that connects the egr valve to the exhaust is rusted and i am fearful of snapping it when going to take the egr off to clean it. Does anyone have any experiance with removing the egr with a rusted connector?

Did you ever pass? I'm having a similar issue to you. I've got my EGR system working, which brought down my NOX levels by almost half, but I'm still sitting at 5.9 instead of the 4.0 required.

 

[Pin_Head]

How do you know the EGR is working well enough? The engine should stall when you pull a vacuum on the EGR actuator at idle. The EGR does most of the work in reducing NOx.
The only other system to reduce NOx is the 3-way catalyst. It is hard to tell how well the catalyst is working, but the exit temperature of the second cat should be higher than the inlet. It is expensive to replace.

 

[runned1]

How do you know the EGR is working well enough? The engine should stall when you pull a vacuum on the EGR actuator at idle. The EGR does most of the work in reducing NOx.
The only other system to reduce NOx is the 3-way catalyst. It is hard to tell how well the catalyst is working, but the exit temperature of the second cat should be higher than the inlet. It is expensive to replace.

Engine stalls with vacuum applied to EGR, VSV tests okay, and modulator tests okay (all ports on the system cleared, intake manifold removed and cleaned). For one test I even bypassed the VSV and modulator so that when throttle is open EGR is flowing, which gives a slight misfire when throttle is under 1000 rpm (indicating EGR open) and evens out with more throttle. With a repaired EGR system I dropped NOX by 5 points, but I’m still over the threshold.

For my cats I have a 100 degree temp increase in both, which means they’re doing something, but I think I’m looking for a larger increase than that IIRC...so my next step is probably cats

 

[Pin_Head]

You might consider O2 sensors first as running lean increases combustion temps and NOx as someone noted above. I don’t think that the 3-way cat makes that big of a difference. You need a 40% decrease.

 

[runned1]

You might consider O2 sensors first as running lean increases combustion temps and NOx as someone noted above. I don’t think that the 3-way cat makes that big of a difference. You need a 40% decrease.

That would hopefully save me some money, that’s good insight. When I bought the truck it had an O2 sensor code, I pulled them, cleaned them (blowtorch method), and repaired a corroded wire. The O2 code hasn’t returned, do you think they might still be out of spec?

 

[Pin_Head]

You roll the dice either way.

 

[ColoradoCruzer]

I did not pass, i got an exemption for two years.... went over the $$ limit for repairs. i failed after i replaced the VSV. The state emissions office said and i paraphrase i need to get the official high ___ toyota cats and perhaps o2 sensors The cats are too expensive to justify the work. After all the work ive done The truck is running pretty great. The truck is currently for sale now. Plenty of power and running excellent. getting to 4 feels impossible on a budget/ cost value analysis. so i decided to sell for a sprinter or bicycle ha.