Failed emissions today 
HC and CO were fine, but NOx was way over at 1483 ppm (850 limit).
1-mistake: JWT ECU. I know people have passed with it but mine has a "ghost" code that happens to be EGRC control solenoid. The "knowledgeable" Ben at JWT told me the EGR system is fine though--false code, nothing more. Still would have been safer to put back the stock ECU which I will do next time. (I passed 2 years ago by removing the JWT)
2-read that high NOx may due to running lean (see above), high combustion temperatures, faulty EGR system, or to a lesser extent catalytic converter issues.
What is the best way to test the EGR system?
After the engine cooled, I tested the EGR valve with negative pressure--the valve indeed works. I even started the engine and put negative pressure and sure enough, the engine idled rough with the addition of exhaust gas to the intake manifold like it's supposed to. I put a pressure gauge on the hose to the EGR valve and when I revved the engine, I did NOT get negative pressure like I was expecting. Was this due to the engine not being warm enough? I tested the input to the EGR control solenoid to make sure it was getting vacuum and it is. How else do I test the control side? I have the Haynes manual but you can only do so much. Particularly the "EGR control backpressure transducer valve"--how the hell do you test that to make sure it is not faulty?
I also sprayed the EGR port at the rear of the intake manifold with induction cleaner from the inside of the manifold.
Q: Could the JWT alone be the culprit? (running lean, *maybe* affecting EGR system).
Q: What else can I do to test the EGR system safely? (ie. no burns please).
PLEASE HELP!!!
HC and CO were fine, but NOx was way over at 1483 ppm (850 limit).1-mistake: JWT ECU. I know people have passed with it but mine has a "ghost" code that happens to be EGRC control solenoid. The "knowledgeable" Ben at JWT told me the EGR system is fine though--false code, nothing more. Still would have been safer to put back the stock ECU which I will do next time. (I passed 2 years ago by removing the JWT)
2-read that high NOx may due to running lean (see above), high combustion temperatures, faulty EGR system, or to a lesser extent catalytic converter issues.
What is the best way to test the EGR system?
After the engine cooled, I tested the EGR valve with negative pressure--the valve indeed works. I even started the engine and put negative pressure and sure enough, the engine idled rough with the addition of exhaust gas to the intake manifold like it's supposed to. I put a pressure gauge on the hose to the EGR valve and when I revved the engine, I did NOT get negative pressure like I was expecting. Was this due to the engine not being warm enough? I tested the input to the EGR control solenoid to make sure it was getting vacuum and it is. How else do I test the control side? I have the Haynes manual but you can only do so much. Particularly the "EGR control backpressure transducer valve"--how the hell do you test that to make sure it is not faulty?
I also sprayed the EGR port at the rear of the intake manifold with induction cleaner from the inside of the manifold.
Q: Could the JWT alone be the culprit? (running lean, *maybe* affecting EGR system).
Q: What else can I do to test the EGR system safely? (ie. no burns please).
PLEASE HELP!!!
Your EGR system might be working properly - it might be that not enough gases are being recirculated because of clogging. That port you sprayed on the IM is prone to clogging, as is the EGR tube that connects to it (runs from the valve to the back of the IM). You could try to clean out the port and tube and see if that helps lower the NOx. It's cheap (just need air intake cleaner and a pick) but a little time consuming.
Yeah, back when I installed the MEVI, I cleaned the hell out of the EGR port and sprayed cleaner down the tube directly. I don't think it should be THAT gunky already. The inside of my MEVI only looks mildly sooty.
Well, I disconnected the the connector to the EGR control solenoid and revved the car. Sure enough, the valve opens with increasing rpm. However, when I put the connector back, there isn't any valve movement. Voltage at the connector is basically alternator voltage. Not sure when the ECU signals for that to be turned off (ie. exhaust gas recirc) but the car was normal operating temperature.
Anways, JWT has been removed and I will go back for testing tomorrow... WISH ME LUCK!
Well, I disconnected the the connector to the EGR control solenoid and revved the car. Sure enough, the valve opens with increasing rpm. However, when I put the connector back, there isn't any valve movement. Voltage at the connector is basically alternator voltage. Not sure when the ECU signals for that to be turned off (ie. exhaust gas recirc) but the car was normal operating temperature.
Anways, JWT has been removed and I will go back for testing tomorrow... WISH ME LUCK!
Failed again. NOx still just as high even with stock ECU. Per Haynes manual, reving the engine to 2-4k rpm and releasing is supposed to make the EGR valve move, but the signal to the EGRC control solenoid does not change (stays at battery voltage) so the EGR system is never activated.. Makes me think that the ECU inputs that control EGR aren't quite right.
Edit: don't understand why the ECU doesn't turn on the EGR. Tomorrow, will get tested again but this time, with the engine warm, I will disconnect the EGRC solenoid harness to turn the EGR system on by force. Hopefully it won't affect the other emissions and will reduce NOx.
Edit: don't understand why the ECU doesn't turn on the EGR. Tomorrow, will get tested again but this time, with the engine warm, I will disconnect the EGRC solenoid harness to turn the EGR system on by force. Hopefully it won't affect the other emissions and will reduce NOx.