code 171 174

golfballs · January 23, 2007

I have been having trouble passing my emissions because of extremly high hydrocarbon levels. (2700) I cleaned the maf and i replaced the plugs, wires, cap and rotor and there is no change.I brought it to firestone and paid them to find the issue and they will tell me to do this and that , but nothing they say works. now they are telling me that my lower intake manifold gasget is leaking oil. would the lower intake gasget have anything to do with the issue i have ? i thought the upper airintake gasget could an issue not the lower intake gasget ? am i nuts or does this make sence?

thank you

jim

pm26 · January 23, 2007

I have been having trouble passing my emissions because of extremely high hydrocarbon levels.

Are you talking about your truck?

golfballs · January 23, 2007

I have been having trouble passing my emissions because of extremely high hydrocarbon levels.

Are you talking about your truck?

Sorry i forgot to tell you its a 2000 gmc g2500 with a 5.7.

Mr. Smith · January 23, 2007

I will bet it is the intake gasket leaking

pm26 · January 23, 2007

I have been having trouble passing my emissions because of extremely high hydrocarbon levels.

Are you talking about your truck?

Sorry i forgot to tell you its a 2000 gmc g2500 with a 5.7.

Looks like you missed the joke entirely. Oh well.

Back to the problem: to get high hydrocarbon levels in the exhaust, you are probably burning oil. Do you have an oil burning issue with the truck? Like adding 1 quart of oil every 1000 miles or so? Do you see a puff of white smoke every itme you start the cold engine? This would indicate leaky valve seals.

Another problem you could have is an EGR valve stuck open. If that happens, a lot of exhaust gases will be mixed with the intake air in the intake manifold. Your truck will lose power and fuel economy will suffer. Check you EGFR valve. make sure it si working properly and the plunger moving freely.