Too many FUMES !!!

[CR55]

Hey Guys, I could use a little advice on what's wrong with my 94 Chevy pickup. It has a 305 in it and it won't pass emissions at M/V on the low speed part. The 3000 rpm test is fine. The fumes coming out of the truck will gas you out. Plus it has a miss in it sometimes, but runs fine over all. It's only getting about 8 miles to the gallon when it used to get 15 or 16. I really don't want to just start replacing parts as you know how expensive that can get!Plus I'm on a loooooow budget . Any help will be greatly appreciated......CR

 

[dogpatch1]

fumes

is this a stock fuel injected truck? fumes mean its rich at low rpm's check for exhaust leaks in front of the 02 sensors, this will cause a rich condition at low rpm but leaner at higher rpm's. also is it a stock thermostat/coolant sensor? lower temp t-stat richens fuel at idle and p/throttle.

clean the intake/02 sensors(use a good spray in induction cleaner like bg products. and install a 200 degree t-stat right before you go for the test. remember the 02 sensors are the nose for the computer and in a sense they tell the injectors what to dump and how long to dump it.

you mentioned a slight missfire at idle? check the ignition rotor and coil if either are weak it will aid in a rich condition by not producing a hot enough spark.

if all else fails rig up a water injection system into a vacuum line(small one) and inject a very small amount of water into the intake.

ive fool'd several emissions test with these little tricks. believe it or not it lowers the co2 and will pass emiss. tests goodluck post what you find. dp1

 

[CR55]

The truck still has everything stock. The injection is a throttlebody. I do detect a slight exhaust leak. I'll check it in the morning. How do you clean the O2 sensors? Thanks for your input..I'll let you know how i make out.....CR:

 

[dogpatch1]

you will actually clean the 02 and the complete intake/ heads and exhaust by spraying a good induction cleaner into the throttle body just hold it off idle alittle and spray it in, rev it occaisionally use a whole can and right befor the can goes empty let the engine idle and load it up till it stahls. (flooding it) let that soak in the engine for a few 5 to 10 min. then start it like you would a flooded engine(hold it to the floor til it starts ) rev it up and blow it out down the road a few times this will clean the entire intake/exhaust system including the 02 sensors, get that exhaust leak fixed, prolly springbolts/studs and gaskets where the manifolds and pipes meet, thats the most common on the chebby trucks. dp1

 

[Sniper]

That strong funny smell could be the cat doing a melt down. A lot of mechanics can tell just by the smell of the exhaust. Also causes the exhaust pressure to increase, causing a leak that may not have developed otherwise. Check around the donut gaskets at the "Y" pipe/exhaust manifold connection. If left to long, it burns out the gasket. The outer shell of the cat may show a hot spot, it would kind of confirm it. Sniper

 

[teerex]

One of the first things to check is engine temperature. If it's low replace the thermostat. A lot of cars of that vintage had the same issues with running rich as the computer would not leave the "choke" mode.

 

[adam]

Change the oil & filter, too.

 

[CR55]

Adam, you're the second person to tell me to change the oil. I don't understand what that has to do with the fumes. Guys, thanks for the help, I'll let you know how I make out.......CR

 

[dogpatch1]

over time the oil gets saturated with contam, and breaks down as it does this it also aborbs fuel, this inturn breaks it down further , guess where the thin broke down oil slips by? yep the rings,guides ect and these contaminates burn in your cumbustion chambers as impurities adding to the co2 levels,

 

[adam]

over time the oil gets saturated with contam, and breaks down as it does this it also aborbs fuel, this inturn breaks it down further , guess where the thin broke down oil slips by? yep the rings,guides ect and these contaminates burn in your cumbustion chambers as impurities adding to the co2 levels,

Yep. It won't hide a mechanical problem or anything majorly wrong, but it does make a difference in what the sniffer picks up.

On a TBI engine, make sure that your gasket between the throttle body & intake manifold isn't sucking air-this is a common problem & cheap & easy to replace. Also, the EGR valve could be sticking open and causing rough running. If it's still the factory EGR valve, it probably has big enough windows on the bottom side that you can stick your fingers inside and see if the diapham moves or not. Should probably be replaced anyway with high miles-all the hot & cold cycles are very hard on the spring inside the valve and it becomes weaker eventually. Many a mechanic has chased symptoms like yours when the EGR valve was symply not working properly. Naturally, newer plugs, wires, & cap and rotor are important too.