Update. The technician at the smog shop asked if my Egr valve and primary oxygen sensor were replaced with oem parts. When he found out they were bought at autozone.... I quote... "take those piece of s*** sensors off and replace them with oem. The autozone garbage isn't calibrated properly for your vehicle. " In any case the egr valve and 02 sensors were ordered and will be here Tuesday. I'll update what ended up happening with the sniff wednesday.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Failed smog for high NOx at 15 mph.
- Thread starter Gabi
- Start date
dirtysouth_msp
Member
- :
- 2003.5 Blazing Yellow MSP (Forged)
Isn't our egr valve completely electronic. I'm pretty sure it does not even have a vacuum fitting...
I lived in San Diego for a couple of years. Getting my car to pass the visual inspection was a major hassle. They have some dumb ass regulations. Most places I went looked in the engine bay and immediately told me that it would not pass with all the modifications. I finally found someone willing to overlook some things. But, my car passed the tailpipe and obd tests with flying colors. I have the same (626) intake manifold set up and had the factory midpipe on it. My car also has a built block with a lil lower compression though, which could be a variable.
I lived in San Diego for a couple of years. Getting my car to pass the visual inspection was a major hassle. They have some dumb ass regulations. Most places I went looked in the engine bay and immediately told me that it would not pass with all the modifications. I finally found someone willing to overlook some things. But, my car passed the tailpipe and obd tests with flying colors. I have the same (626) intake manifold set up and had the factory midpipe on it. My car also has a built block with a lil lower compression though, which could be a variable.
Last edited:
dirtysouth_msp
Member
- :
- 2003.5 Blazing Yellow MSP (Forged)
How high are the NOX readings over the allowable?
How high are the NOX readings over the allowable?
459 is the max and Im at 794.
hornsfan10609
Certified Mazda Tech
- :
- 2003.5 Mazdaspeed Protege x2
I highly doubt replacing the EGR and O2 sensor will do anything unless they were malfunctioning before. On the stock tune with functioning cats you shouldn't have any trouble passing
That's the thing. Everything else is within spec with the exception of that damned 15 mph test high Nox. I'm even starting to think it might be a wiring issue or pcm issue.I highly doubt replacing the EGR and O2 sensor will do anything unless they were malfunctioning before. On the stock tune with functioning cats you shouldn't have any trouble passing
dirtysouth_msp
Member
- :
- 2003.5 Blazing Yellow MSP (Forged)
Running lean can cause high NOX. Were the HC readings very low in the same portion of the test? If so, it could be lean. If you have access to a wideband, you could check this pretty easily. If you are sure you have no vac leaks (smoke test is best way to verify), then your MAF or O2 sensor may be malfunctioning. I have heard that aftermarket O2 sensors kind of suck for these cars, but I can not verify that. I've only used OEM. May be helpful to clean the MAF. If the MAF is reading less air volume than actual, The ecu will not add as much fuel.
So O2 sensor was replaced with OEM counterpart along with a brand new OEM EGR valve. The idle is noticeably smoother. Ill keep you guys posted. I took some pictures of the OEM vs Duralast EGR next to each other for comparison. I'll try and upload the pictures tomorrow along with a smog update. HC readings were low, but according to my wideband the car is running between 14.0 Af ratio and 15.5 af ratio at those engine speeds. What is the normal range for the air fuel ratio?Running lean can cause high NOX. Were the HC readings very low in the same portion of the test? If so, it could be lean. If you have access to a wideband, you could check this pretty easily. If you are sure you have no vac leaks (smoke test is best way to verify), then your MAF or O2 sensor may be malfunctioning. I have heard that aftermarket O2 sensors kind of suck for these cars, but I can not verify that. I've only used OEM. May be helpful to clean the MAF. If the MAF is reading less air volume than actual, The ecu will not add as much fuel.
Last edited:
hornsfan10609
Certified Mazda Tech
- :
- 2003.5 Mazdaspeed Protege x2
That's normal, the engine is trying to maintain a 14.7:1 ratio at idle or when cruising.
That's normal, the engine is trying to maintain a 14.7:1 ratio at idle or when cruising.
Good to know. Does anyone have any clue how long the pcm needs to relearn the fuel trims etc? I've only driven it for about 50 miles since replacing the O2 sensor and Egr valve. Is that enough?
Rusty Buns
Member
- :
- 03.5 MSP , 04 MSM (titanium X2)
Running lean can cause high NOX. Were the HC readings very low in the same portion of the test? If so, it could be lean. If you have access to a wideband, you could check this pretty easily. If you are sure you have no vac leaks (smoke test is best way to verify), then your MAF or O2 sensor may be malfunctioning. I have heard that aftermarket O2 sensors kind of suck for these cars, but I can not verify that. I've only used OEM. May be helpful to clean the MAF. If the MAF is reading less air volume than actual, The ecu will not add as much fuel.
God I hated living in California as a car guy... ^ this is correct. NOX is usually a byproduct of hot combustion chamber. As stated, vac leaks can cause this as well as carbon deposits in the chamber creating hot spots, also a malfunctioning EGR can do this as well.
A smoke test works great but if you don't have access to a smoke machine I suggest the "hillbilly leak test". Get a handheld propane torch and crack it open a little (don't light it!) and start to wave it near vac lines, gasket surfaces and intake joints. When you hear the idle rise up you've found your leak. Obviously if you wave it next to the air intake port the idle will rise.
List of things I would try:
vac leak test
clean MAF
seafoam intake ingestion
inspect EGR passages for carbon blockage
How are your NOX levels for the other tests? Are they close to the limit for the other tests or way lower?
hornsfan10609
Certified Mazda Tech
- :
- 2003.5 Mazdaspeed Protege x2
Honestly there isn't much a dealer can do that you haven't already done. Mazda has an engine cleaner like seafoam but it is only used on the 13B rotary motors.
Sad to hear. The car has been in their possession for 4 hrs now, still no call. I'm hoping they can figure out WTF is wrong. I'm more surprised by the lack of MSP's in Cali that can chime in. I'm also concern I'm gonna have to go through this bs every year now. I'll keep you guys posted.Honestly there isn't much a dealer can do that you haven't already done. Mazda has an engine cleaner like seafoam but it is only used on the 13B rotary motors.
sorry to hear your having such trouble i dread smog time as well, what type of bypass system do you hvae are you still on stock and if so when was the last time the bypass valve was replaced...
Im actually using an audi TT bypass valve. It was installed about three months ago. Its recirculated the same way as stock. I've never had so many problems with smog before.... Another MSP owner incentive huh? lol The car is still at the dealership.... I quote: we were swamp today and weren't able to get to it today. Tomorrow first thing in the morning we'll take a look at it... Needless to say I was pissed off! I'll update the thread once I hear back from the stealership.
Last edited:
I'm trying... thanks for the help so far by the way.stay strong buddy
Similar threads
- Replies
- 5
- Views
- 2K
- Replies
- 0
- Views
- 1K
