This truck passed smog 18 months ago at Valley Hybrids in Stockton for the PO. I will be working my way through the emissions system item by item, but does a failure of this magnitude point point to a particular item to try first?
Has anyone had a worse HC smog test result than this? What should i try first? Sorry for another smog thread... (1 Viewer)
- Thread starter gaylon
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RodrigzCrzr
SILVER Star
Smog pump
Or exhaust leak or vacuum leak.
Working on a 60 right for the same thing but not that high of numbers.
Or exhaust leak or vacuum leak.
Working on a 60 right for the same thing but not that high of numbers.
- Thread starter
- #4
2F
The catalytic converter no longer functioning?
Fuel mixture is too rich?
Air filter clogged?
This engine needs a tune up regardless
-Maybe- it didn't pass 18 months ago either, but $omehow a smog cert was given. Stranger things have happened.
Fuel mixture is too rich?
Air filter clogged?
This engine needs a tune up regardless
-Maybe- it didn't pass 18 months ago either, but $omehow a smog cert was given. Stranger things have happened.
Last edited:
- Thread starter
- #6
The catalytic converter looks to be OEM and I guess could be original. Truck has 171K miles on it. I will look to see if the mixture has been adjusted. Air filter would very dirty, just changed it. Going to new smog on Tuesday to get an updated baseline after checking all smog hoses and valves.
Your O2 numbers are very good, so it's unlikely smog pump /Air Injection system.
How old is the CAT?
High HC is from lean Mix where there's too much air and you get misfires so raw fuel going out. This kills CATs quickly, too.
Vacuum leak going into one or adjacent cylinders could do this, also faulty components in Ignitions system, so as OSS said, full tune up with wires etc, if they're old...
Put a vacuum gauge on it and see what it reads at 700 rpm idle.
How old is the CAT?
High HC is from lean Mix where there's too much air and you get misfires so raw fuel going out. This kills CATs quickly, too.
Vacuum leak going into one or adjacent cylinders could do this, also faulty components in Ignitions system, so as OSS said, full tune up with wires etc, if they're old...
Put a vacuum gauge on it and see what it reads at 700 rpm idle.
Having never done a smog test, do they not grandfather you after 25+ yrs?
Not in CA, though there may be a few counties that do little or no testing...
In CA you have to get your horse smog tested every year
RodrigzCrzr
SILVER Star
Every other year.
