Older Gas And Smog Test

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ButchW

ButchW

Well-known member
Joined
Apr 14, 2021
Posts
568
Location
La Mirada, CA
I'm in CA (LA County) and need to have my gas MH smogged... I haven't had the vehicle out since last Thanksgiving, so the fuel in it is that old... I have abut 1/4 tank in it now... Should I just take it down and get it tested?... Add more fuel to dilute the old gas?... Or try to run it out before testing, and refuel?... It runs fine on the fuel now and I run it monthly or so, but I'm concerned about it not passing and being tagged a (Gross Polluter)... It is a very low mileage 2012 Ford V10... Thanks for any suggestions...
BUtch
 
I don't know if this applies to motorhomes. The last time I smogged a vehicle, all they did was connect the OBD port and download some files, didn't measure any tail pipe emissions. Just take it for a quick drive on the freeway to get it nice and hot then go to the smog stations. The gas is not that old.
 
I think you are worrying needlessly. Last Thanksgiving was only 4 months ago, so within the 3-6 month minimum shelf life of gasoline. And in actual practice gas is typically good for a year or more anyway. Nor does deteriorating gas quality necessarily mean it would flunk emissions testing, even though there may be a loss of power. The combustion management system can and should cope with that. However, if you want to play ultra-safe, top off the tank with fresh fuel.

This article may help set your mind at ease.
 
The computer will adjust for any change in octane, down to a certain point, and adjust timing accordingly so the engine runs optimally. Otherwise SMOG is checking proper operation of things like the catalytic converter, O2 sensors, AIR system, etc. Like others have said, the gas is only a couple months old and you're in California - of course, depending on where, but usually not a very extreme climate over the winter.
 
I have serval older vehicles that are only driven 2-3 thousand miles a year that have to be smogged. I always change oil, fresh gas, and flog them hard for 10 miles or so before inspection.

I also have a new smog fuel cap that I use for smog tests only.

Here, the plug in obll test only goes back for vehicles 10 years old or newer.
 
I'm in Clovis California and was in the same situation a couple months ago. My Workhorse 8.1 engine had sat beside my house for 18 months without putting gas in it. Covid and also had a heart attack so we weren't traveling.

I always store it full of gas so it was about 3/4 full as I run it on a regular basis

Talked to several smog places and got various opinions.

Finally took it to the smog place and it passed with flying colors so I think you will do fine.
 
Another CA story ... we recently passed our 2004 Suburban to our son in the MidWest. It had sat on our driveway rarely used since we bought an Explorer in 2018. Before son flew in, I took care of some things, such as put on new tires, poured some fuel stabilizer in the tank, added 'fresh' gas, and proceeded to the tire store. En route I saw the 'check engine' light had come on, although the engine seemed to running just fine.

While waiting for tire install, I looked at the Burb handbook, and the first paragraph under Troubleshooting|Check Engine Light said: 'Have you added fuel lately? If so, it's an emissions control issue, the most likely cause being the fuel cap'. From there, I went to an auto parts store, bought a new gas cap, but the light stayed on.

Off to another auto parts store and had them check the error code. Sure enough, it was an emissions control error. Stopped by an auto repair shop, and they rolled out a list of emissions-related parts that might need changing.

Got home and research showed that the auto parts store couldn't legally cancel the code they read (so their web site said). Additional research suggested that the fuel additive might have caused the emissions control system to "sniff something unusual".

I ordered an OBDII tester, which confirmed the error code, but also allowed me to cancel it. Son had some additional things done in prep for his trip home, including an oil change and bought new wipers. He drove the car 2,400 miles to the MidWest (lots of fuel top-ups), and the error light has not re-appeared.
 
Here's a CA smog experience that happened on an old Honda Accord that sat unused in our driveway until we eventually passed it to our daughter. It ran like the day we bought it 15 years earlier, but I usually disconnected the battery for long-term non-use. Took it in for smog test and it failed the last test. Tech asked if I'd installed a new battery and, when I told him it had been disconnected for some time, he explained that the computer had lost its memory, and that we should drive it for 100-150 miles so the computer would re-learn what it had lost. Took it back 200 miles later and it passed with flying colors.
 
Washington State did away with emissions testing a couple of years ago. I'm so glad. I've never had a car not pass, but I have had to take off from work or go out of my way to get the car tested, that was a real pain.

The thing with check engine lights is they typically do not reset immediately following a fix. It generally takes a couple engine cycles before the ECU no longer considers the fault active, and then the codes are stored in history. Resetting the car's computer just before an emissions test is a surefire way to fail the test.

A lot of emissions issues are common to a make/model. For example, just about every single rubber hose that joins evap lines under a 97-up Dodge Dakota will eventually fail, causing faults for an Evap leak. It's about a $7 piece of 3" rubber hose which joins a big line to a small line. So if you've got a code, Google it, and on an older vehicle, chances are somebody knows something or has been there before!
 
When I bought my MH almost two years ago, it had been sitting for a couple of years. It had a full tank of old gas in it. I put a can of Seafoam in it, and ran it for a couple of days. I then took it into "Just Smog" in Huntington Beach and it passed just fine. 2003 Fleetwood Tioga 29V.
 
As was just mentioned: Seafoam. Sta-Bil is another good one. Well worth the cost. I keep a 5 gallon can for lawn mower, generators, power washer & chainsaw. When the gas gets to 2-3 years old I put it into my trucks tank. Never had a problem.
 
Pedro Dog said:
The last time I smogged a vehicle, all they did was connect the OBD port and download some files, didn't measure any tail pipe emissions.
Click to expand...
AFAIK, they always check tailpipe emissions on motorhomes, in both CA and NV. My Y2K RV is a CA "gross polluter" which means it always will be until it totally passes a CA smog test.

I had an easy fix. I smog it in NV where it always passes. They still check from the tailpipe. They only used the OBD2 connector to get the correct RPMs. In NV, it can even pass with the check-engine light on. But in cars, it will fail if the check-engine light is on. In NV the RVs and cars are tested totally differently. But NV has looser specs than CA.

In CA they can get my Y2K RV to pass if they step on the gas pedal so the slow idle is at the highest speed allowed. But most smog check palaces won't do that--except at the place that sells the RV. I have posted many messages in this forum about this problem. It had to do with when the RV was made from the Express Van, the CC's had to be moved back where they do not get hot enough. So when my Y2K RV was new, it would not pass the CA smog test after it was made into a motorhome.

-Don- Auburn, CA
 
Skookum said:
The thing with check engine lights is they typically do not reset immediately following a fix. It generally takes a couple engine cycles before the ECU no longer considers the fault active, and then the codes are stored in history.
Click to expand...
I'd read that online but, in the case of our Burb, multiple cycles and drives didn't cancel the fault.
 
Tom said:
I'd read that online but, in the case of our Burb, multiple cycles and drives didn't cancel the fault.
Click to expand...
After resetting the light, some codes that will not "get ready" in a million miles if you do not drive in a certain way. It takes more than miles for some of the codes. Such as driving near a certain speed and costing to a stop. If you're driving hundreds of miles on a freeway, you may not ever do that.

Also can require a couple of starts when the engine is very cold.

I use a "Get Ready" thingy to tell when my sensors are ready for a smog test. But this does NOT apply to RVs in NV. But some OBD2 testers can also do it:

 
Thanks for all the help folks… I just talked to the tester ( He is a RV mechanic as well)… He told me not to worry about it, and just bring it down… He has done well for many of my family and friends, so I believe him..
Butch
 
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