I posted this on the engine forum as well....

My 86 F-250 (351W HO) failed emissions testing in MD for Hydrocarbon emissions. I took a look at the air filter and breather and they are both wretched. The literature from the state says the PCV and EGR should also be replaced. Are these two replacements difficult? Are there any other things I should be focusing on.

Also, the engine runs great when it warms up, but is a little rough when cold. It has a manual choke set-up and the choke cable keeps getting bound up. It looks to me like the L-Bracket holding the choke cable in alignment is not strong enough to keep from flexing. Also, the cable seems to be too long, could this be a problem.

Thanks!

Greg

 

What are your numbers like? If you failed HC's, most likely you have an ignition problem. Depends what your no's are and when it failed. Do they do just an idle and a loaded test there? Take a look at your plugs, wires, cap and rotor, and check your timing for starters.

 

EGR and PCV are not difficult to replace. Try to get the Manual for your vehicle. On our 1982 Ford E150 5.8L V8 351W, the EGR is on the rear and the PCV is on the passenger side valve cover. Try removing the EGR and clean the hardened carbon from the passages on the EGR itself and the passages ways to the intake manifold. The PCV can just be replaced since it's very cheap.

Clean your air filter housing and the area where the Air Breather goes in. Use new Air Breather and Air Filter. You might to remove the hose (probably metal and connects to the engine oil filler tube that goes to the driver side valve cover) and clean it good because on our vehicle it was gunked up with hardened carbon.

Hydrocarbon failures usually indicate improper timing, vacuum leaks, worn spark plugs/spark plug wires, distributor and failing ignition coil. I would replace then replace spark plugs, spark plug wires, distributor cap and rotor are cheap so why not replace them. Check for vacuum leaks and deteriorated vacuum hoses.
Add some fuel treatment in the gas tank.

Probably your catalytic converter is failing and not burning any excess gases.

Read this article as it might apply to your State emission devices they are using http://www.ctnow.com/news/local/hc-f...eadlines-local

 

Thank you for the replies.

The plugs, wires, etc. were all replaced shortly before I bought the truck a few months ago. There is no cat. conv. anymore, just a straight pipe to a muffler (this particular vehicle is exempt in MD).

The Hydrocarbon number was 5.13-something - don't have a clue as to what this means. The max is 4.-something.

They run a Dynomometer test on a treadmill simulating a 5 min drive up and down hills, through all gears. The test guy said the test indicates the failing numbers at points where gears were changed?

Thanks!

 

Is this an auto? Do you know what your CO was? Did they give you a "drive trace"? If so, can you post it? If it's good up to the point where it shifts (higher rpm's) I would suspect your timing is off.

 

Sorry, I don't know why but my signature doesn't show up on posts anymore. It has my truck info.

My truck has the c-5 4spd manual, no overdrive trans. I'll scan the printout and post it if you think that will help.

 

I think it will. I keep forgetting about running my mouse over there with this new format.

 

Ihave an 84 f-150 and it passed in MD (waldorf)w/out the tredmill test mine was never put on the dyno and i have no smog control on my truck except the cat

 

Thanks, I'll scan it tomorrow and post it.