Thanks,

Still don't know about old gas. I checked my records & my mileage over the last 2 1/2 years & its become apparent the gas in the tank now is half
2 1/2 yo gas.

I'm trying to deal with this now as it could be affecting the smog emissions.


All the other parts of the smog test except NO seem to indicate an engine running fine.
HC & CO are fine. Does this mean that the fuel is burning well? Wouldn't old bad fuel be more likely to mess with the HC & CO? Seems when fuel gets old its less volatile so not burned completely which would increase the HC & CO.

Would old gas act in a way that would be similar to a lean fuel condition if its not burning well?
Also says high engine temp cause hi NO. The engine does run hot but has a new behr radiator & thermostat.


I'm trying to cut out this step of finding someone to take out about 3/4 of my gas approx. 15 gallons if it's not needed.

Also if HC & CO levels are fine doesn't this mean the catalytic converter is working?

engine - Best Ways to Pass Emissions? - Motor Vehicle Maintenance & Repair Stack Exchange


Mosts emissions tests will check NOx, CO and HC. A very basic rundown:


•NOx - Oxides of nitrogen. This means the engine is running too hot (2500F +). This can be caused by poor cooling or fuel mixture is too lean. Modern vehicles also have an EGR system, which exists exclusively to reduce NOx. If the engine is running in the correct tempuratures, and NOx is high and everything else is normal, the EGR system is strongly suspect.

•CO - Carbon monoxide. CO exists when there is an incomplete combustion of the air/fuel mixture. This can be caused by restricted airflow (dirty air filter), or a sensor that is reporting the incorrect airflow (MAF/MAP, TPS), or a faulty O2 sensor.

•HC - Hydrocarbons. This is raw fuel, meaning the fuel didn't burn completely during combustion. This can be an ignition problem such as misfiring, or poor timing. Usually this will show up as a driveability problem.


http://www.smogtips.com/failed-high-NO-nitrous-oxide.cfm



What Causes High NO (NOx)?
Nitrous Oxide or NO is created when an engine's combustion chamber temperature reaches over 2500F. Vehicle manufacturers have designed several systems, which when working properly, lower nitrous oxide emissions. Below are common failures which may cause your car, truck, van, suv, or motorhome to produce high high nitrous oxide.

1. Lean Fuel Mixture - Lean fuel mixtures cause high NOx. A lean fuel mixture exists when less fuel then required is delivered to the combustion chambers or when more air then necessary is added to the fuel. In either case the lack of gasoline needed to cool the combustion chambers down is not present. Combustion temperatures increase causing high nitrous oxide emissions. A lean fuel condition may be due to a vacuum leak/s (possible) and/or defective fuel control components, such as the Air Flow Meter, Engine Coolant Temperature Sensor, and O2 sensors (new).

2. Defective EGR System - The Exhaust Gas Recirculation system is designed to reduce NO. The EGR system consists of an EGR valve, EGR pressure sensor, vacuum hoses, and one or more vacuum switching valves or solenoids. Later model vehicles may be equipped with electronically controlled EGR valves, which do not require vacuum lines or switching solenoids. Electronic EGR systems will have these components built in.

The EGR system's job is to re-route a small amount of exhaust gas back into the intake manifold to help reduce combustion chamber temperatures. As mentioned above NOx is created when combustion chamber temperatures reach above 2500F.

By recirculating exhaust gas back into the intake, a small amount of the air/fuel mixture is replaced with inert gas, reducing combustion temperatures.



3. Defective Catalytic Converter (CAT) Some vehicle manufactures have designed their cars to operate without EGR valves. Non-EGR equipped vehicles rely heavily on the Catalytic Converter to assist in the reduction of NO. These vehicles have tendencies to develop CAT problems sooner then those which are equipped. If you own a non-EGR equipped vehicle, and have failed the emissions test for high NOx, pay close attention to the Catalytic Converter.


4. High Engine Mileage - Over an engine's lifetime, carbon build-up develops in the engine's combustion chambers. The more miles on your engine, the more carbon build-up on the pistons, cylinder heads and valves. Carbon build-up decreases the available space for the air/fuel mixture to combust, and causes higher cylinder compression. High compression results in high temperatures and high NOx. Keep in mind this problem is usually seen in vehicles with over 150,000 miles which have been poorly maintained. The solution to this problem is called De-Carbonizing. It usually costs around two labor hours at a smog check repair station. It will remove a good amount of carbon out of an engine. This will increase combustion space, lower compression and lower NOx. ( Engine has close to 200,000)

5. Engine Overheating - Inadequate engine cooling can will high NOx. If your vehicle's cooling system is not working efficiently, (i.e. bad radiator, thermostat, hoses) high NOx will be created. Remember high NOx nitrous oxide is created when an engine's combustion chamber temperatures reach over 2500F. You will want to make sure your vehicle's cooling system is working properly, and your vehicle's temperature gauge is always indicating normal.

__________________


83 500 SEC Euro 198K

Any time I see a NOx failure, I immediately suspect the EGR. As for the old gas, can't you just drive the car until it gets low? On a 500 SEC I don't imagine that would take long.

__________________
Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.

Thanks for the advice,

The EGR was checked about 100 miles ago. Guess its still a possibility.

As for driving I paid the registration fee but it its not legally registered since this smog was required 6/2015.

I got a ONE day permit to move the car for smog.
It was smogged Feb 27 month where it failed.
I have less than 20 days left on this permit to do this smog repair.
I did not write in the date I moved the car the last 2 times but every time I do this I chance getting pulled over & having to write in that date really fast or chance getting a ticket or worse an impound.

I think a car unregistered over 6 months is an automotive impound which is something I don't want to chance.

I don't have the luxury of driving the car to use the gas.

I considered fast idling it in the garage but that would take about 10 hours & most likely clog things up more?

To be frank it barely passed NO 2 1/2 years & 70 miles ago with 19 gallons fresh gas. So it did have NO issues. Then it sat 1 1/2 years without use
because I was sick & the battery died.
This last smog it was a gross polluter with NO.
(I posted the last 2 smogs in a earlier post)

I have about 2 weeks left before this ONE day pass expires.
I'm just not sure if DMV will issue another ONE DAY pass when this one expires. That's a 45 minute plus call to DMV. I suppose I have to make that call & hopefully it will give me more time.

__________________


83 500 SEC Euro 198K

Now you can put your number in for a callback from the DMV. That way they ring you back when it is your turn. That is much easier to deal with.
Dreaded smog tests can be a real pain.

__________________

Chris
84 280sl
82 300d euro

If this were my car, I'd pull the EGR valve off and see if the passages are carboned up. If so, I'd clean them out, put the EGR valve back on, double check for function, and then take my one day pass and hit the highway for a couple hours to get rid of the old fuel, then fill up with fresh and re-test.

OTOH, if I failed to find evidence of reduced EGR flow, then I'd be suspecting mixture issues, which would require more extensive research on my part, since I know very little about the fuel injection system on that model.

Edit: I just remembered a bit about ignition timing. Later timing can decrease NOx at the expense of higher HC and CO. Have you checked the timing on the thing?

__________________
Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.

I really appreciate the advice. Been trying to think if I know of anybody I trust to drive the car on the highway to try to clear it out but I really don't.

I'm not well & am on medication. I have not driven in 1 1/2 years. I don't drive on the highway. I can barely drive it a few miles as I don't feel well enough to drive.

Life has not been easy the last year & I have put off this smog issue for a while.
I have no one to help me but I have not given up on myself or the car yet.

I can't work on the car but am trying to understand these things to try to not get taken on these things by repair as I'm broke.

I know I really shouldn't have this car but I'm hoping I can find a way to keep it.

Enrique at MB motors said the egr was ok 100 miles ago. He basically has taken care of the car since 7/2007 but he couldn't help w smog emissions. I don't think he ever checked timing but I really don't know. It has all new radiator, thermostat, wires, plugs, distributor cap, rotor, accumulator & O2 sensor.

Kartek who won't help me this time did have a mechanic 2 1/2 years ago 70 miles ago in the cars history got it set up to pass smog. Nothing has been touched since then.

My economy gauge has also never been pegged on minimum when idling so guess that means something. Maybe a vacuum leak? Maybe a smoke test? I changed most every rubber vacuum hose I could reach even the big ones.

I have been told not to worry about the gas & to just have a new cat put on & see if that helps. I might even try the $200 upfront guy if I think he will really go through it & get to the issue if its running related as its not a car that just any smog repair place is going to be familiar with.

I do appreciate everyone's suggestions.

__________________


83 500 SEC Euro 198K

Half-right half-wrong! Retarding spark advance reduces peak combustion temperature, which reduces engine-out NOx.

It also INCREASES EGT, which will keep the catalyst hotter making it more effective at oxidizing HC and CO.

Shorting the R16/1 resistor along with plugging the vacuum advance signal line yields signficantly retarded spark advance under loaded dyno emission test conditions.

The reduced rate of spark advance with revs with no contribution from the vacuum advance at moderate load creats a dramatic reduction in engine-out NOx, and the hotter catalyst promotes maximum oxidation of HC and CO.

If the O2 content is zero, the catalyst is hot enough to be working at peak effciency by using all the O2 exiting the cylinders and formed by the disassociation of NOx.

If O2 is more than 0.2 percent the catalyst is either degraded or not hot enough to maximize all potential reactions.

Duke

Can you do a non-op on the car until you're healthier and less broke?

__________________
Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.