I just failed my second emissions test. Long story short, I tuned up the engine, new wires, cap, rotor, set idle and timing within specs. Plugs show I am running lean, my compression is 115 to 120 with 130 on one cylinder. I ran some guaranteed to pass stuff through the system, ran the engine hard before testing it, and ran a quart of denatured alcohol with a quarter of a tank of gas.

My hydrocarbons are only a little less than they were the first time. I am still over 100 PPM than max for the HC's.

I have a large amount of smoke coming out of the breather tube, and enough pressure to push out the PCV valve while driving if the breather tube is blocked.

I suspect the high HC's are from blow by, but why do I have the high compression numbers?

The smog tech said it might be the heads, how do I test them? I do not want to throw parts at this to na avail.

Please help me.

Thank you,

Nick

 

Oh yeah, I also changed the oil and added a can of Restore.

 

What weight oil did you put in?
If its thin oil then that could hurting you.
This whole thing is BS.
Do you know of any places that for an extra $20 will " Help " it pass?

 

Nick,

A high hydrocarbon count generally means there's significant unburned gas in the exhaust
and can be indicative of a misguided fuel delivery system, weak ignition, vacuum leaks,
to name a few. It sounds like you've replaced much of the ignition system, I'm assuming
you've replaced/cleaned/inspected the plugs relatively recently? Just because the plugs
would seem to indicate the engine is running lean doesn't mean that's necessarily what's
going on inside the engine, their condition could be a faulty diagnosis.

Is your AIR pump working correctly? EGR valve? Both of those devices are supposed to
operate only at specific times, e.g. at full operating temperature and while over ~2,000 RPM.

Blow-by is made up of combustion gases making their way past the rings and into the
crankcase, after which time they're supposed to be re-ingested into the combustion
chambers via the PCV valve. The exhaust system is nowhere in sight, I don't see how
such gases can, by themselves, cause your high-HC problem. I don't know what you're
talking about when you describe smoke and breather tube, are you referring to one in the
top of a valve cover? So long as your PCV valve is functioning correctly, I'd imagine
those gases would get sucked into the chambers.

I suggest you find a good local mechanic who can do what is known as a leak-down test
(google it) and can otherwise help you better diagnose it; try googling on 'high
hydrocarbons emissions' and read about it, you might get some ideas from there, too.

 

Quote:

Originally Posted by bill11012

Do you know of any places that for an extra $20 will " Help " it pass?

Shops around here generally aren't corrupt like that, they'll lose their operating
license and be out of business if they're caught. The TV news stations perform
undercover operations on these kinds of places, taping the entire scene.

 

glad i just read that note on a "leak-down" test from <b>chris</b>...i'm already sweating my smog test and it's not up for me until summer...

 

What engine is in the truck?

My 300 was like that 4 years ago and it was due to the catalytic converter being defective.

 

A leak-down test can tell you if your engine has, say, burned valves. In general, I don't
recommend that test as a first course of action for diagnosing emissions-related problems.
There's a guy out here named 81-F-150-Explorer who's in California and knows a LOT
about these things (particularly 6-bangers) and he can be a great resource if you can get his
attention. Diagnosing stuff like this over the Internet is almost as bad as trying to diagnose
engine knocks via text descriptions - once you pass the easy & common things, it can get
orders of magnitude harder and time-consuming, hence, at that point, I generally suggest to
people to bring it to somebody who can SEE and HEAR it and who has the right equipment
& tools and who knows their stuff.

 

Whoa! Seems they got your attention!

 

If the PCV valve is popping out of the VC while drivng, I'd be looking into the entire PCV system. The metal pipe that runs between the PCV valve and the carb/intake is prone to plugging up. Sounds like yours is there/nearly there.

 

keep us posted, please

 

Maybe i am imagining things, but did you come back from the netherworld?

Welcome back to the land of the tinkerers...

 

Hi guys,

Sorry I did not clarify, it is a 351 HO. The truck has no cat (came that way) and I was told it is illegal to put one on.

I am wondering if it is vacuum related. The only reason I bring up the blow by is because the HC's did not go down between the two tests. I agree, it is almost impossible to try to diagnose this over the internet, I am just trying to figure out how deep this problem might be. Could I be looking at a whole new engine? I hope not, and am even willing to replace the heads if I need to, BUT I am hoping I might have something plugged or bad vacuum lines.

The PCV valve popping out only happens around 20 to 25 mph when I intentionally colgged the brerather (to keep the fumes from going into the air cleaner).

Thank you,

Nick

 

Ya know, those fumes are SUPPOSED TO make their way to the air cleaner, it's that
valve's job to allow just that.

 

Ummm, actually, no. They go the other way around. Fresh air from the breather, fumes thru the PCV valve into the the carb/intake (depends on design).