Smog Check (1 Viewer)

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Jan 24, 2022
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Failed the CA smog test on Saturday and I am looking for some guidance on how I can *try* to clean up my emissions before heading to the shop and having a new catalytic converter installed. For context I did nothing to prepare for the first test and only drove 5 minutes across town to the test center.

Since Saturday I have changed the oil, replaced the gas cap, and checked the air filter (looked pretty new/clean to me). My plan is to run the tank to near empty then put in a few gallons of e85 or 91, drive 30-40 minutes on the highway at a high rpm, and pull right into the test center while the truck is still hot. My question to you guys is: should I use e85, 91, heet, guaranteed to pass, or something else?

I can retest for $39 so I’d like to try one of these options before heading to the shop. I know the topic has been covered but I’m interested to hear some feedback from those who have tried, whether it worked or not, and how dramatic the change in test results were. Thanks all!
 
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You’ll want to read through the thread linked below: Same symptoms and fail point. (high CO an zip O2).
Likely an air injection issue.

Lower octane gasoline is better for a smog test than premium. One old time cheating method (which is supposed to be checked by the technician) is retarding the timing.

Those fuel tank additives (Heet) that are supposed to help pass smog are primarily alcohol. It’s not illegal or against the rules to use it.
Alcohol in the gas will both raise the octane in a fake way but lower emissions- but it’s hard on the rubber parts of the fuel system.

The “proper” way to pass your test is test and likely fix whatever is going wrong with your air injection system.
The cheap & dirty way to -maybe- pass if you’re lucky, is add some alcohol to the fuel, do the procedures you mentioned above — and pray.
Maybe you’ll squeak by. Maybe not.

 
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^^^What @OSS said. That's my journey on the way to passing smog. Once I made sure the air injection system was running per the manual, my O2 jumped up significantly. I found other links to try to be sneaky about it but only was going to resort to that if I failed the 4th time.

A couple of other things to add is that make sure your engine is properly warmed up prior to having it tested. My first few failed attempts I drove to the smog shop and it just made it to operating temp. This last time, I probably drove around 30-40 min and also kept her running before the smog tech took her in - on the 4th attempt, I wasn't taking any chances. The first 3 tests I went to the same smog shop - the low cost solution which was busy all the time. When they saw my '85, they knew I wasn't a get 'em in, get 'em out test. On the 3rd test is when I kept her running before the test and tried to keep her as warm as I could prior to the test. The smog tech was going back and forth in setting her up on the dyno while getting other modern cars in/out at the same time. I failed but barely. I got a recommendation for another smog shop and he was less busy and only takes appointments so I knew I'd be put on the dyno right when I got there.

YMMV but I'm running stock 2F, rebuilt OEM smog pump by BZ rebuilders, rebuilt OEM carb about 3yrs ago, original cat (but thermosensor is toast) and all functioning original VSVs, ABV, ASV, and check valves.

I was where you were after my 1st failed test and thought I'd be able to do some things here and there but it wasn't really after going through the AI that got me to pass. Good luck. Post up any other questions. I'll be happy to pass on the knowledge I've gained from the other MUD members that helped out and that I just put into practice.
 
A weak air pump will give you the numbers you see. E-85/Heet is a good solution (or part of the solution), as is a new/reman air pump that puts out a good wind (and making sure that this air makes it all the way to the engine). A buddy of mine in Boise had no air pump at all on a Ford pickup, got similar numbers, dumped in some E-85 and passed easily. I would run the truck down to maybe 3 gal. of regular fuel and then put in 2 gal of E-85. Don't be too timid about putting enough in. Then, immediately after the test, fill with real gasoline and burn it out.
 
So I went back and re-tested today. I’m not going to lie, I took the easy route and put e85 in the tank then drove ~30 mins on the freeway prior to testing. The change in my emission results were pretty astounding. However I still FAILED, this time because of the fuel evap test. The crazy thing is I passed this on the first go. Anyone had this happen to them before? Could it have been an error on the testers part?
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I replaced the gas cap after my first test so it makes sense that I would pass there, but I didn’t touch anything else so it seems odd that the issue would just now pop up. How involved is replacing the evap hoses? Maybe I’ll start there if it’s a simple weekend job.
 
Two yrs ago on my first smog test I failed on EVAP and passed on everything else just like you (but no e85). Smog tech told me to fill up my tank and come back in two hrs. He said a full gas tank has less space for gases. I did that and passed. He thought maybe my charcoal cannister was bad. But this recent test I didn't have any issues but from the research I did most MUDers go in to test with the least amount of fuel in the tank. Not sure who's right here.
 
@ro11dice you might be on to something…my first test had 3/4 tank of gas, tonight I had less than 1/4. Wonder if that will make the difference. Damn I’m jumping through hoops to get this thing smogged…
 
This is not the fuel cap. You can see there is another test specifically for the cap. In this test the cap is removed and the tank and lines are pressurized looking for leaks. I had this happen and replaced the hoses associated with the vapor recovery system (evap). There is a vapor separator in the right rear quarter panel and the the hoses associates with the charcoal canister. Of course if your canister has a hole in it that could be the problem too.
 
Third time's the charm. I filled up this morning, re-tested and passed on all fronts. Seems low fuel level can contribute to, or exacerbate EVAP leaks.

Now that I can complete my registration I should have some time to actually do some maintenance. Also looking at some pretty significant oil leakage so I will be combing through the forums on replacement of seals.

Thanks to all of you guys for your continued troubleshooting and encouragement. This forum is a fantastic resource.
 
A slow EVAP leak became my nemesis in later years. Technically I’d fail it but the tech would fiddle with stuff long enough to make it pass (and I’d tip him).
I had a 48 gallon double sized gas tank and I’d NEVER fill that sucker (except before long trips) so that may have been the problem- there was over 33 “gallons” of air space inside the tank which the EVAP pressurizer probably couldn’t account for.

So I learned something from this thread too!
Full tank is the way to go.
 

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