Things to do or not before smog test? (1 Viewer)

[e9999]

OK, here comes another required CA smog test.
Passed just fine a bit over a year ago, but I'd rather not have to deal with problems and have to go back... Plus this may give me the necessary motivation / excuse to do something worth doing on the truck...

Anything I should or should not do before taking the test?

I have replaced the plugs recently, the plug wires test fine, and I will probably put in a new rotor and cap by then. Also replaced PCV and air filter.

I was thinking of running a couple of Techron injector cleaner bottles in the gas for a few weeks taking the test. That should not hurt.

I have also been thinking for a while about doing the "Suck Seafoam in the intake" trick but I'm wondering if that's a good idea to do it now given that that would likely dissolve and make a bunch of gunk flow around. Waddaya think? OTOH, it might clean things up a tad.

Taking the intake off and cleaning the inside seems way overkill, no?

(Only 78k or so)

 

[offroadkid]

My friend is a smog tech. He says changing the oil sometimes helps. Here's a link I "Googled"

http://www.smogtips.com/six_things.cfm

 

[e9999]

My friend is a smog tech. He says changing the oil sometimes helps. Here's a link I "Googled"

http://www.smogtips.com/six_things.cfm

I'm surprised. Not sure how the oil cleanliness would be reflected in what is reinjected by the PCV... Maybe more fumes?


I do remember reading here that somebody noticed a temporary improvement in smoothness with cleaner in the gas... maybe not a bad thing if there is some left in the gas during the test?

 

[Lars]

I've always heard new oil and clean air filter helps.

 

[Hants]

Replace the gas cap. Mine passed inspection, but the tech cleaned/wiped/inspected it for a long time (many 10's of seconds) before he put it on the machine.

Several weeks later I discovered it was leaking fuel -- now I wonder how it passed the pressure test at all.

Also, I've heard that if you've recently had the CEL light reset (fixed the underlying problem or not) or disconnected the battery, they can/will fail you for insufficient data.

I'd be leery of additives or wild-n-crazy cleaning exercizes within a tank or two of testing.

May you pass the first time!

 

[Gumby]

If you have an OBDII truck (96+) you will need to have all of your monitors enabled to pass. You can't just reset your light.

I fast idle mine while waiting in line. I see people fail because the cats get cold while they are waiting. I run 1500+ RPM to get it nice and hot.

 

[e9999]

If you have an OBDII truck (96+) you will need to have all of your monitors enabled to pass. You can't just reset your light.

I fast idle mine while waiting in line. I see people fail because the cats get cold while they are waiting. I run 1500+ RPM to get it nice and hot.

so clearing up all the codes even if no CEL is not a good idea then -assuming I could even do that-?


any point in putting premium in for the test?

 

[Brentbba]

Just go and don't worry about it. hehehe

 

[elmariachi]

so clearing up all the codes even if no CEL is not a good idea then -assuming I could even do that-?

In Texas, the inspection station computer can tell if you reset the codes in the last 300 miles. Likely the same in other states, considering that everything we have here our legislators learned or stole elsewhere.

 

[NorCalDoug]

Just go and don't worry about it. hehehe

Ditto.



I've never had a problem with any of my 80s passing smog. The one I sold 4 years ago (1994 model year) passed with flying colors -- I had done nothing to it aside from a tune up a couple months prior to selling it.

My assumption going into these tests is that if the rig is running well, I won't have a problem. If it's running rough, fix the problem before taking it in. Maybe I'm just spoiled with Toyotas (and hondas).

 

[Darwood]

In Texas, the inspection station computer can tell if you reset the codes in the last 300 miles. Likely the same in other states, considering that everything we have here our legislators learned or stole elsewhere.

I'm not sure if OBD-II even holds that detailed of information. I'm about ready to call BS on this but I need to do some research first.

Of course you all realize this just gives the pre-95 guys more room to talk.

 

[RavenTai]

In Texas, the inspection station computer can tell if you reset the codes in the last 300 miles. Likely the same in other states, considering that everything we have here our legislators learned or stole elsewhere.

Not in GA on a friends late 90's Chevy blazer, it that case you can clear the codes with a scanner in the parking lot 50’ away and as long as it does not set the code again it will not fail, but if you clear the codes by disconnecting the battery then it will have to go through a "drive cycle" (whatever that is for that vehicle) before it will pass. for Chevy I think a drive cycle was one warm up & one cool down. nto sure waht it is for an 80.

No tail pipe sniffing in GA for 96 on, making the post 96 superior here.

 

[Darwood]

Not in GA on a friends late 90's Chevy blazer, it that case you can clear the codes with a scanner in the parking lot 50’ away and as long as it does not set the code again it will not fail, but if you clear the codes by disconnecting the battery then it will have to go through a "drive cycle" (whatever that is for that vehicle) before it will pass. for Chevy I think a drive cycle was one warm up & one cool down. nto sure waht it is for an 80.

No tail pipe sniffing in GA for 96 on, making the post 96 superior here.

As far as I could tell by my research, OBD-II only sets "readiness flags" after a certain drive cycle which tend to involve 30 mph driving and 55 mph driving. Other than that, it seems OBD-II doesn't seem to store information other than thrown codes.