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I failed emissions with high Nox, which is why I started to test the EGR system. The valve does not lift when reving the engine between 2K and 4K. However, I have functionally tested it to see if it would hold vacuum. It does lift when applying vacuum directly from the throttle body. The other time it works is when I disconnect the purge control solenoid valve, thus permanently sending an OFF signal and allowing vacuum to pull the valve open.
So why isn't the ECM turning the valve on and off on its own? I also verified continuity between the ECM and the EGR temp sensor and purge control solenoid valve. It's as if the valve is always in an ON state, which is cutting the vacuum to the EGR valve. Could a faulty engine coolant temperature sensor cause this permanent on state? What else tells the ECM to turn the solenoid valve OFF?
in a stall test rev your egr will not lift cause there is no load...if your able to run vacuum to test ur egr then there should be no ecm control on it its all vacuum control...one of the best way to test your egr is basically turn your car on and run it...then put ur finger under the egr and push up against the egr and close it off...if your car stall then ur egr is perfectly fine...if i doesnt stall then you have carbon build up and it needs a cleaning...
I have a 1996 Nissan 200SX SER. The engine is an SR20DE with california emission specific parts. I just noticed though the other day when I was warming it up that the EGR valve did in fact lift when reving between 2k and 4k. One thing I did while troubleshooting was thuroughly clean the connectors to the temperature sensors since there was a lot of oil on them from a chain tensioner housing leak. I am going to take it in for another shot at the title (smog cert). Wish me luck!
The EGR solenoid operates between CLT 167F and 221F based on load and rpm. If the CLT sensor is out of range, CLT is set to 86F and is incremented 1 degree every 6 seconds, up to 178F, so the EGR solenoid will operate even if the CLT sensors is bad. Also, the EGR solenoid does not operate if the MAF sensor voltage is below ~1.0V.
A few things I have learned about the EGR solenoid:
The default position of the solenoid is Off, which turns the EGR on.
The ECU commands power to the solenoid to turn off the EGR as Dave mentioned, so if your coolant temp. is too low (this happened to me when I had a thermostat that was stuck open and the temp. never got over 160) the EGR doesn't open.
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Tim Rogers
'93 NX2K- Sapphire Blue, HS Gen 4, JWT S3's, Ported & Polished, P/R CAI, JUN Flywheel, Coil-over / AGXs, 15X7 RPO-2's, 205/50/15's.
'91 NX2K- Black, parts car
'92 NX2K- All out SCCA Improved Touring A race car.
Yes, it's Greg Amy's former car.
And yes, I've broken it...
Hi ChrisAce,
I wanted to see if you ever got your car to pass SMOG. I am also in CA (stupid SMOG laws) and driving a 92 NX2000. I took it in to smog the car yesterday and the NOX was double the legal limit.
I have already tested the EGR valve, its good. I did notice that there is almost no vacuum coming from the BPT valve and no exhaust going into it.
Also, the smog guy said the timing was way Retarded (at 5 Degrees). I know i have to adjust the timing, but does anyone else know why the NOX are high?
It sucks that this car isnt passing smog, it runs awesome. If it doesnt pass, ill have to junk the car, or sell it for parts (or take a bat to it).
I have already tested the EGR valve, its good. I did notice that there is almost no vacuum coming from the BPT valve and no exhaust going into it.
The metal tube that goes from the EGR tube to the BPT valve is clogged. At the junction of the two tubes, there is a pinhole orifice and when it gets clogged, the whole EGR system stops working. If you are lucky, you might be able to spray some carb or parts cleaner down the tube and blow it free with compressed air. If that doesn't work, you'll have to remove the EGR tube and get at the orifice from the other side with a paperclip, needle, etc.
Quote:
Originally Posted by theitalianflip
Also, the smog guy said the timing was way Retarded (at 5 Degrees). I know i have to adjust the timing, but does anyone else know why the NOX are high?
My guess for the the retarded timing is a bad knock sensor.
When the ECU fully retards timing (like when the throttle is fully closed under deceleration) the timing goes to 5 Deg. If yours is at 5 Deg. all the time, I think it would be due to a knock sensor that has "gone soft" and triggers all of the time, causing the ECU to pull timing.
I would check the timing with a timing light for yourself to doublecheck.
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