failed emissions

Ok fellas. Today I brought my truck in for emissions and she failed. Everything was where it was supposed to be at except for the hydrocarbons. It supposed to be at a 1.0 and it was over 4.0 something. I just tuned her up, plugs, wires, cap, rotor, new TPS, etc. Im going to buy a new highflow cat and O2 sensor and turn my FPR down a bit before i bring it back. Would this fix the problem? Its a 1990 1500 with a 350 TBI no mods except a edelbrock 14 inch open element.

Bad cat would be my guess, unless the plug wires arn't all the way on or somthing like that. Give it a smack, and see if it rattles.
Oh, vacuume leaks can cause high hydrocarbons too, check for those. Retarding your timing can bring it down as well.

Won't a bad EGR valve cause high Hydrocarbons as well? Or would it be a combination of HC's & something else (I don't remember the other gases emitted through the exhaust).

If you think the plugs are not all on, run the car and see what the idle speed is. Hook an inductive tach onto each plug wire and see what RPM is has. If one has no RPM or way diffrernt, there is the problem.

NoX

Originally posted by Smooothie119
Won't a bad EGR valve cause high Hydrocarbons as well? Or would it be a combination of HC's & something else (I don't remember the other gases emitted through the exhaust).
EGR is mostly Nox, it lowers hydrocarbons slightly, but not anywhere near what he is experiancing.

Hmm, My truck doesnt have air injection to the cat or the exhaust manifolds. That means i dont have an EGR valve? So how do i have to fix this problem.

Has it passed before while you owned it? Perhaps it did have injection, and it was removed and thats why its so high? You may or may not have EGR, check for one, its probably on the intake manifold if its there. Your doing the cat anyway, so do that, run it, if its still screwed its probably somthing with your ignition.

My dad owned the truck before me since it was new and it did not come with any air injection. The truck was very well taken care of. Never beaten on and its the cleanest one iver ever seen. Thats why I dont understand why its acting up. So what is going to solve my problem.

If you still have the stock air cleaner throw it back on for the test and change your oil if it's been a couple of months since you have. You would be surprized what changing the oil will do,plus the open eliment won't allow the pcv to evacuate properly. Just a thought. :)

Why won't the PCV work? Ive got $10 on the cat or ignition, any takers? :)

Originally posted by PyRo9862
Why won't the PCV work? Ive got $10 on the cat or ignition, any takers? :)

Sorry I did not say it would not work I said would not work properly,however I should have said as efficent. :)

Always check the cheap fix first....

Woops, I do not have the stock air cleaner any more. So add change the oil to the to do list before i go in also. Anything else?

before i go to the emmissions i change the spark plugs, run the tank of gas down and pour in like 3-4 bottle of fuel injection cleaner and drive hard on that, then fill the tank. clean off the rotor terminals, my lincoln has an EVR filter the size of a cork that is washable, i take off the egr and clean the hoses and channels, oil change, clean air filterand drive the car real good before i take it in. you should be good to go if everything is in order after that.