Failed smog for high NOx at 15 mph.

[Gabi]

Some background....

*The intake manifold was replaced with a 626 intake manifold along with the EGR pipe from an 01-02 626.

*The EGR valve was replaced with a durmast counterpart.

*The stock exhaust manifold was replaced with a steed speed stock replacement manifold.

*Less than a month old NGK spark plug wires and Sparkplugs (stock heat range)

*Both ignition coils replaced with new duralast counterparts.

*No Vacuum leaks

*Small leak at turbo inlet (Bought new gasket and will be replaced this Saturday)

*Running stock midpipe with one of the cats replaced with a carb approved cat.

*Passing with flying colors at 15 and 25 mph test for all other measured content (CO, etc)

* Running Valvoline VR1 10-30 synthetic racing oil. (if it matters)

Im at a complete loss as to what else to look into. The engine has 170,000 miles so for that reason I sea foamed it and just finish running a full tank of gas with the CRC Guaranteed to pass additive. I am now debating paying a shop to decarbonized the engine (is that even worth it?) Any and all help is appreciated. I was sent to a star certified smog station here in San Diego CA and have no connections to "pass" the smog test in case anyone was wondering.

 

[hornsfan10609]

Although I don't use it myself I have seen things like seafoam and the CRC tank additives actually work. They may not be enough to pass but should lower the numbers a little. If you have the stock mid pipe or access to one I say the best bet would be to swap it on and try it out. Try an oil change too, if it's recent it may not help but I have been told this before when trying to pass my ex's car.

You are making me glad I live in Texas.

 

[Gabi]

Although I don't use it myself I have seen things like seafoam and the CRC tank additives actually work. They may not be enough to pass but should lower the numbers a little. If you have the stock mid pipe or access to one I say the best bet would be to swap it on and try it out. Try an oil change too, if it's recent it may not help but I have been told this before when trying to pass my ex's car.

You are making me glad I live in Texas.

Thanks for the reply. I'm actually really starting to consider registering the car in Arizona were my brother lives. I guess I'll do an oil change this Saturday along with the gasket and another round of seafoam. Now the VR1 has a high content of zddp, I'm starting to wonder if that could play a role on NOx levels. I just finished the tank of gas that had the CRC additive and seafoamed it on Saturday. The car does idle smoother. I'm debating going with one step colder on the plugs and see if that makes a difference.

 

[hornsfan10609]

Plug heat range probably won't make a difference, the colder plug may actually make it worse.

 

[Gabi]

Plug heat range probably won't make a difference, the colder plug may actually make it worse.

Once more thanks for the help. It seems Im the only MSP owner in CA that's had this problem considering no one else has commented lol

 

[hornsfan10609]

Unfortunately not too many people are on here anymore, or are MSP owners. Gotta keep the platform alive

 

[Preferio]

Like 90% of the MSPs are in three places- Canada, Texas and Florida.

Any chance you have access to PIDs? Specifically modes 1 and 5. That way I can look at each value to get an idea of each input sensors health?

 

[Gabi]

Like 90% of the MSPs are in three places- Canada, Texas and Florida.

Any chance you have access to PIDs? Specifically modes 1 and 5. That way I can look at each value to get an idea of each input sensors health?

I use the torque app on my phone to read codes, clear codes etc. What is mode 1 and 5 maybe I can get that info through the app or go get a diagnostic.

 

[CHIQLES]

Maybe you have a stuck injector do you have a wide band

 

[Gabi]

Maybe you have a stuck injector do you have a wide band

Wideband is reading a steady 14.7 to 15.3 a/f ratio while cruising and a pig rich 10.0 under boost.

 

[hornsfan10609]

Stock tune? Maybe try to reset the computer to reset the fuel trims and drive the car real easy while it relearns.

 

[Gabi]

Stock tune? Maybe try to reset the computer to reset the fuel trims and drive the car real easy while it relearns.

Yeah stock tune. On another note. Can someone provide the part # for the egr vacuum solenoid. Just went to the delearahip and they couldn't pick it out from all the solenoids on the diagram. I suspect I might have gotten the wrong one. A pic would work as well. Thanks.

 

[Preferio]

They are all the same. Really. I've broken like 5 between all my engine removals. I took the ones off of my RX8s failed engine to replace the last two I broke. Almost every Mazda from that era uses the same ones.

 

[hornsfan10609]

There are two types of solenoids. The part numbers on the bottom either end in '90' or '91', you just have to match the last two numbers.

 

[Gabi]

The part #'s I got for the two I bought are Z504-18-741A and KL01-18-741. One was $118 the other $143 so I hope they are the right ones.

 

[Preferio]

The part #'s I got for the two I bought are Z504-18-741A and KL01-18-741. One was $118 the other $143 so I hope they are the right ones.

If a part number has an 'A' or 'B' or 'C' suffix that means it's the same sensor, but has been "changed" for some reason. Possibly due to a common failure or something along those lines. An "engineering change" I think is the terminology manufacturers use.

 

[Gabi]

If a part number has an 'A' or 'B' or 'C' suffix that means it's the same sensor, but has been "changed" for some reason. Possibly due to a common failure or something along those lines. An "engineering change" I think is the terminology manufacturers use.

So basically one of the sensors has been improved right? In any case I don't have a check engine light or anything. I'm just going down the list of things associated with the egr and crossing my fingers.

 

[hornsfan10609]

I was referring to the numbers on the bottom of the solenoid

 

[Gabi]

I was referring to the numbers on the bottom of the solenoid

I see. Thanks

 

[Gabi]

Back from the dead. So I went back to the stock intake manifold (had a 626 before) hook everything up back to factory specs and my Nox reading at 15 mph only went down 100 ppm. I have 5 days to get it to pass or I can't drive the car anymore. I'm at a complete loss. Egr valve has been replaced already. Any other ideas?