MichaelKLerner

EXECUTIVE SUMMARY: Seafoam, and cataclean were apparently worthless. colder plugs probably made all the difference.

First, let me introduce by saying I wanted to submit this as a tech write-up, but I am not allowed to do so, hence this post. Also, I searched the forum and was unable to find any documentation related to my particular experience, so I want to record this for others.

This is my first CA smog test since I bought the truck,pre-smogged, in 2016. The bottom end of the engine is fairly new, seems to be about 30K miles (very tight). I have no records from the previous owner but I know that the engine was recently assembled because when I bought it there was Permatex where there should have been actual gaskets; therefore, I know it was rebuilt.

The initial smog test produced the following results:
· CO around 0.15
· HC around 90
· NOX around 1300

Failed because of excessive NOX (top of the range is around 700) and timing was 8 degrees advanced.

In response to the failure, I made the following initial changes:

· Set timing to 0.
· Checked the EGR pipes for carbon. None found.
· Checked the vacuum hoses for cracks. None found.
· Tested the EGR diaphrams. All good.
· Changed the air cleaner filter. Needed changing anyway.
· Used Seafoam spray just in case the cylinders had carbon build up.
· Ran 91 octane.

Smogged again. FAILED. No change in results. Seafoam was useless.

Second round of changes:

· Resumed using 89 octane, with 1 can of cataclean.
· Changed plugs to one heat range colder than stock. Old plugs were dirty, rusty red colored deposits, which could have been from the Seafoam.
· Changed the oil using motor flush. The crankcase was truly dirty.
Smogged again. PASSED.

New results:

· HC around 90. Unchanged.
· CO around 0.80! Way up, but still within limits.
· NOX under 400! Way down.

I would have loved to have been able to be truly scientific and change only 1 factor at a time before each retest. But time is never on my side when the state is withholding the sticker on my primary transportation. Therefore, I was forced to throw the kitchen sink at the problem and hope for the best. I can only guess that the colder plugs made the difference because it is the only change that can both lower NOX and increase CO at the same time.

I would say IMHO, however I have no humble opinions, only the normal kind...

I think all the octane, Seafoam, and Cataclean in the world wouldn't have made a difference. Just a bunch of snake oil.

Epilogue, now that I have my DMV sticker, I can reset the timing to 8 degrees advanced, because 0 degrees is a mfg mistake, in my opinion. I believe 0 degrees BTDC it causes Drivability problems, especially in standard shift vehicles, where the engine can stall on launch when heavily loaded, or on hills, if you don't give it a lot of gas. (My clutch thanks me.)

MichaelKLerner

Epilogue (Continued): Within 2 weeks after passing smog with colder plugs, I had to change back to the regular hotter plugs because apparently the cold plugs were fouling too easily, causing hard starting and rough idle. I'm keeping the colder plugs for my next smog check, in 2 years.

L5wolvesf

Fouling in what way? Pics of the plugs would be very helpful.

MichaelKLerner

I don't remember. Doesn't matter. Reverting to the hotter plugs took care of the hard starting and rough idle.