I have a 83 F250 that just barley failed the max CO%
This engine is a 351 cu. and only has a little over 5k on it. The last time I tested it passed easily on the dyno. This time they gave it an idle test because they claimed it was too big for the dyno (37" tall tires x 14" wide)

My test results for the idle test were:
HC (220 PPM) my reading = 169 PPM
CO (1.2%) my reading = 3.3%

Is there anything "easy" I can do to lower the CO%??
I hardly ever drive this truck...could that be part of the reason it failed?

hmmm... Rich?


I think a good romping on would of help...

if you hardly drive it, class it as a show car and then you dont have to worry about emmisions. just have to keep under so many miles a month

When ever my parents take any of our older vehicles in for emissions they fill it up with premium and then drive them pretty hard, like taking them out to old back roads and opening them up to clean everything out, sometimes you can see smoke come out of the exhaust if you floor it. That would be the simplest thing to try.

I couldnt tell ya whats wrong without looking at the car.
But, heres a nice article for you to read.
I'd check EGR frist pesonally.


http://www.automotiveu.com/zack5gas.htm

throw some methonal in there and take it back.

Maybe some injector cleaner?

Most important question, is it carbed or injected? Also is it the original cat or a replacement and how old is it age and mileage wise?

check egr and all emission related products ie.. smog pump and do what everyone is saying premium and drive the chit out of it

Thanks for all the replies...

I know that there was alot of gray area without detailed info.
First off it's carburated, has a mild cam, hollow cat and prior to me owning it the smog pump had been removed. I just rebuilt the engine about 2 years ago, but like I said, I drive it maybe a handful of times throughout the year.
It could just need some better fuel and a good pounding.

Jerry, Like Mich said, fill with premium, and add two botthles of heet additive. It's alcohol, burns hotter and should help that.

it doesnt burn hotter but it burns cleaner. Since you barely just failed you shouldnt need much at all. Add a bottle of emission stuff sold at any auto store. Do that with like a quarter tank left.

just put 93 in it and 2 bottles of rubbing alcohol in it...you will pass

LOL I like this. Higher octane fuel can make you fail worst! I.E. 89 Camaro with a 350 slightly built with 93 octane failed but with 87 passed!!! Just romp on it a few times before you take it in, you prob got some junk built up in the motor from not running it a lot. And whatever you do don't buy the fuel injector cleaner that you pour in your gas tank, it does nothing! I'm sure Rich can get his hands on the good stuff!! Also I have seen a T.A. pass with no cats or o2's and an 700 lift cam with 1.5 roller rockers! all depends on how much you pay the guy!

And this is why I live way south of I-80, and you guy's pick on people bout us rednecks? I'd lean the carb out quite a bit and turn idle up a touch so it won't load up! Try that and ya might just pass.

Good luck, Matt

I'd probably try to adjust the carb, put a fresh tank of the current 87 octane gas in the tank, run the piss out if that tank, refill and go back for the retest.