igogusto

Hello All,

Today I had to do a Smog Check and I failed. It failed the NO portion of the test. I am in California.

I have done the Deckplate Mod and the ISR mod. Would those cause me to fail the Smog check? Of course, I forgot to close the deskplate prior to the test. I have another chance to do the smog check without charge, but I wanted your opinions on whether the mods that I have done could cause the failure.

I am thinking that the O2 sensor could be the cause, but I do not have a scanner to check which one to change. I do not have a CEL at this time.

MARSHALLMAY

make sure your truck is good and hot before the test. The exhaust has to have a chance to warm up the cat to operating temperature. If it was hot during the test then you might want to close the deckplate. If that doesn't work you might start checking o2 sensors and cleaning the maf.

igogusto

MAF should be clean. Cleaned it about 500 miles ago. I just don't want to waste the free smog test by closing the deckplate, if it is an O2 sensor.

Rhew Runner

If you do fail again, go to a "test only" center and usually you can find one that offers "pass or don't pay". That's the only way I do it nowadays.

Good luck.

igogusto

Rhew,

I had to go to a Smog Only station. The ones out here only let you try to pass smog 2 times I guess. I guess that I will try it again with the deckplate closed. Crosses his fingers!!!

habanero

Good luck, though mine passed at a St. Louis smog check w/deckplate open, no problem.....once I got the obdII fixed to connect with their computer.

igogusto

Nice bike Habanero,

Not too sure what you mean in the thread about the ODB scanner though.

hotlavaaaa

Keep the engine running while you wait. The cats have to be hot to work properly. I passed a CA smog test with the elbow removed so I wouldn't worry about the deckplate being open.

grimpy

When I was going to sell my Runner, I almost failed smog... This is with a 6 month old 02 sensor, spark plugs, fuel filter, MAF cleaned, and new air filter. I also have the ISR and deckplate. I barely passed the NO section... Four months later, I had to do my bi-annual smog... Two days before, I did a seafoam treatment and I passed the smog with flying colors on all the measurements...

Might want to give seafoam a try. Also don't forget to drive around for awhile as others mentioned to heat up your cats.

MTL_4runner

Running high for NOx would indicate that it was running hot/lean so I don't think the deckplate or truck not being hot enough was your problem. My money would be either on the MAF or the front O2 sensor (although it could be a few other things, fuel injector, fuel filter, vacuum leak, converters, etc). What was your NO reading and what is the Cali limit for your vehicle?

k_southman

Seafoam is awsome. I run it in my truck, boat, quad, snowmobile!

igogusto

MTL - here is the NO info. Weird that it was even higher with the Deckplate closed.

1st time - Deckplate OPEN

15mph - 688 FAIL - CA Max 512
25mph - 686 Pass - CA Max 765

2nd time - Deckplate CLOSED

15mph - 787 FAIL - CA Max 512
25mph - 741 Pass - CA Max 765

Car was good and hot and left running before check.

I thought that Seafoam will foul your plugs and your O2 Sensors???

Is there an EGR valve on the runners?

grimpy

That is what I believed about seafoam and is the reason why I waited so long to do it. I actually had the bottle sitting at home for over 3 months before I bit the bullet and gave it a shot.

It worked great and my readings were alot lower than 4 months before. I also didn't change any parts on the vehicle.

I'll try to dig up my past smog reports and give you exact numbers.

Again it might not be your problem but it cleared up a good amount of crap from my vehicle.

MTL_4runner

Ok that is a good sign since you are only marginally over (not at the gross polluter level yet I don't think). First of all you do not have an EGR system on your motor. If it was my truck I'd look at the items below.

Check for problems with the following:
- Air injection system (MAF, O2 sensor, vacuum leak)
- Combustion chamber deposits (this can include the plugs as well)
- Dirty fuel injectors (injectors and fuel filter)

I would go about solving it by:
1) Run 2 cans of Seafoam or BG44K, 1 in the gas tank and 1 through a vacuum line
2) Change your spark plugs if they are over 25k miles old
3) Change your fuel filter if it is more than 40k miles old
4) Clean your MAF with some electrical contact cleaner

The Seafoam can cause alot of havoc if you put alot in at once before you've run a can through the gas tank first. Basically if you run it in a vacuum line right away it will tend to loosen all the deposits at once and you can have issues. The preferred method is to chip away at them a bit more slowly and then do a clean sweep on whatever remains at the end. Only after you do the seafoam should you go an replace all the other items (plugs, fuel filter, etc).

Then retest and see how you stand.

igogusto

I heard an interesting theory from the Instructor that teaches Auto Technology at the College that I work for, as to why I might be failing Smog. He asked if I had added oversized tires or rims to my 4Runner. That I have done. I put 16" rims and larger tires on my beast. He said that leads to the engine working harder to achieve the speed at which they test the emissions, resulting in more emissions. DUH! I should have thought of that!!! He is going to take a look at my 4Runner on Wednesday. I will post some info after he has done some testing. Of course I do not have my stock rims and tires, BUT my wife has a 97 4Runner and I can swap the wheels if need be!

igogusto

Ok the instructor tested my runner today, with bad results. He tried to get it to test smog running in low gear, but it still failed NOx. He said that the only way to get it to pass smog was to put on the original wheels and tires, have the computer re-programmed for the larger tires, or change the gearing. Damn that sux. I have no idea what this is going to cost me!!!

MTL_4runner

Have you followed any of the other suggestions? or just tested again?

igogusto

Everything has been cleaned/changed within the last 5000 miles. I did not try the Seafoam. Will that help lower my emmissions?

MTL_4runner

The answer is it might if you're running lean at all (which you are if you have high NOx). In fact you might try having a place do the full BG44K service for you since the BG is a bit more potent than seafoam and has been proven to work very well.

jrallan26

Have you changed your oil before a smog check?

When I was a California resident that was the trick, make the sure the engine was at operating tempature with the oil changed. Never failed.