High NOx at 15 MPH smog test

I misspoke earlier. EGR Valve about $145, Catalytic Converter who knows because of the California bullshit, probably $200 or more.

The prices listed for cats on most auto parts sites are 49-state models, and I need the California model for more money.

 

Ouch. You're in California? Ya... try $600 for a 2nd Gen cat, and ya, well over $200 for a 1st Gen.
Sucks because the cat is identical to the 49-state cat that sells for half the price.

 

Did I mention I absolutely hate living here?

Maybe I could get one on Ebay for less...

 

Or drive to AZ/NV/OR and have one installed there.
Same cat, it'll still pass, and the inspector won't look for the EO number.

The law prohibits a shop from installing a non-EO on a California vehicle.
AZ/NV/OR shops aren't going to give a shit about California law. Pay cash and tell them you don't need the receipt.

 

Like said above. If you don't have the CEL, go replace the EGR valve first. A high flow cat from magnaflow is a much cheaper alternative than an OEM replacement so go that route when replacing.

 

X2 on the magnaflow cat if needed. My sister had one put in her CRV. I think it wound up being like $400. She was getting $1000 quotes from the dealer and a couple other shops.

 

What really annoys me about this is I might be moving to Texas this summer. But my California registration expires at the end of May and I need to get it smogged this year.

The emissions regulations in Texas vary by county, so a new cat or EGR valve may or may not be needed.

In other words, I may be flushing money down the toilet.

 

EGR does provide some benefits besides emissions.....if the engine was designed to run with it. Since yours is stock, I think this would still apply. On my old 22R, it used to knock with an inoperative EGR. This is because the EGR lowers combustion temps. Before I figured out what was wrong, I was backing the timing down to compensate and stop the knocking. This hurt my gas mileage and power. You can bet the computer on your truck is compensating in some way if your issue is EGR related.

 

Yeah, very possible.

I keep track of all my gas fill-ups (business tax writeoffs) and have noticed my MPG decline 1 maybe 2 MPG compared to when I bought it 12 years ago.

 

Based on the chart I posted, what is the consensus?

- Replace the EGR first, then get it smogged, or
- Get it smogged and replace the EGR only if it fails, and if it fails again with a new EGR, then replace the cat?

Does anyone know the consequences of failing smog multiple times in California?

 

I would TEST the EGR first. Make sure it's working at least somewhat by manually activating it, if possible. If it's a vacuum activated valve, you can use a vacuum pump, or just a long piece of hose, then suck on it. This should stall the engine at idle, or at least make it run rough. Then I would take it down to get it smogged. No high dollar fixes just for the sake of smog numbers unless it's needed.

Now, it's worth noting that the smog tech is supposed to manually test that valve anyway. But just because it runs rough when activated does not mean it's working to it's full potential. My 22R would run rough at idle when the valve was manually operated, when I pulled the connecting pipe off to clean it, all but a pencil lead's diameter hole was clogged.

I would focus on making sure all the EGR passages are clear before buying any parts. I wouldn't buy any parts until you've actually failed smog.

As far as I know, there are no major problems with failing smog until you are a gross polluter. That means double the allowable emissions. At that point, the process of getting it repaired and passed gets complicated. You have to get it fixed in one shop, then smogged in another......and I think there is some more money involved also.

You can ask for a pre-test, meaning they test the emissions levels without hooking up their machine to the state's computer system. Then they will do the actual test once they believe your levels are low enough to pass. You might have to pay extra for it, but worth saving the hassle of a gross polluter label.

 

Are the Toyota EGR valves vacuum driven?
The valve on my '95 Suburban was, but my '93 Blazer (4.3 Vortec) was an electronic pintle (and very prone to becoming stuck open from carbon).

OTOH, if the pintle was not in the commanded position, it would throw a CEL or pending CEL so it was usually pretty easy to confirm.

 

I admit I don't know if the Yota's use vacuum valves. I am guessing they do, because as you say, an electric valve usually would have a position sensor on it.

 

Speaking of which, I took this photo a couple years ago, it's the EGR vacuum modulator. Inside is this filter element. Does it ever need to be replaced?

Obviously a little dirty on the top, but not sure if that restricts air flow or not.

 

Nahh. The filter is just to keep any dirt "inhaled" from being drawn into the intake.

The one on my '95 Suburban was just a foam cap that looked like a black version of the common yellow ear plugs.
It was one of the first parts to get "lost in the wind" during servicing and I've never seen a TBI Chevy with one still on it.

 

with the co2 at 15% cat seems to function alright, a good functional cat and good combustion efficiency should have the co2 at 14+%

I really don't think its your cat because your o2 is Low its not Too high.

with your HC and CO being a bit high it sounds more like incomplete combustion. Those numbers do look a bit rich.

give those plugs a change and I'm Willing to bet a beer your hc and co will be lower. Now for NOx look at what your timing spec says, you are allowed +- 3* for smog. retard it just 2-3* itll help lower it a bit. If not then you got to bite the bullet and get a new EGR.
also make sure theres enough coolant in your truck, it might just help lower the NOx a bit

 

The plugs (Denso) have maybe 20,000 miles of city driving on them, but they look decent for their age ... no crud or bad wear. Would you still replace them?

Thanks for the reminder on the coolant. Radiator is fine but the overfill tank looks a little low.