I Failed a CO emissions test last week with high Nox. Today I put 50 psi in my tires, a bottle of heet in the gas tank and I lowered it a good bit but still failed. The first test I was 4.5 with the max being 4.0. The second test I hit 4.1.
I have read that EGR problems can cause high Nox so I cracked my FSM and tested some things, I was hoping you guys could help me make sense of the results.
During the test with the "T" connector between the modulator and the EGR, I read high vacuum at 2500 rpm. from what I understand, this is wrong.
I tested the vacuum modulator and was barely able to get any air through port Q (while blocking off the other two ports) regardless of engine RPM. I also tried putting a vacuum pump on the bottom port and was still unable to get any air through port Q with or without vacuum applied.
I applied a vacuum to the EGR itself with the engine idling and it immediately died. Which from what I understand means the EGR itself is working.
So here is my understanding of the situation, The Modulator has failed, which is allowing the EGR to operate more often than it should. Shouldn't that lower my Nox if anything? I understand that more EGR means my engine is running less efficiently than it could, so I will replace it either way, but this probably isn't going to help my emissions issue, right?
I also found that my intake tube is cracking, and was already repaired by the previous owner, so I ordered a replacement. Should I test my O2 sensors next?
I have read that EGR problems can cause high Nox so I cracked my FSM and tested some things, I was hoping you guys could help me make sense of the results.
During the test with the "T" connector between the modulator and the EGR, I read high vacuum at 2500 rpm. from what I understand, this is wrong.
I tested the vacuum modulator and was barely able to get any air through port Q (while blocking off the other two ports) regardless of engine RPM. I also tried putting a vacuum pump on the bottom port and was still unable to get any air through port Q with or without vacuum applied.
I applied a vacuum to the EGR itself with the engine idling and it immediately died. Which from what I understand means the EGR itself is working.
So here is my understanding of the situation, The Modulator has failed, which is allowing the EGR to operate more often than it should. Shouldn't that lower my Nox if anything? I understand that more EGR means my engine is running less efficiently than it could, so I will replace it either way, but this probably isn't going to help my emissions issue, right?
I also found that my intake tube is cracking, and was already repaired by the previous owner, so I ordered a replacement. Should I test my O2 sensors next?