Hydrocarbons through the roof.Limit is 220,I got a 1351. <img src="/forums/images/graemlins/barf.gif" alt="" />Could be a problem.This is on a 91 4R 3.0 auto 4x4 with 159K.Everything else passed.Is there a specific component(s) that affect the hydrocarbons?I just recently changed the plugs,wires and cap/rotor with Bosch parts.The engine runs a little rough at idle but smooth at anything above that.The mechanic thinks it might be running rough from a stuck EGR flooding exhaust in the intake and not an electrical problem since it runs good when tested at 2500rpms.Any ideas?Thanks.

Damn that is high. I took my 84 4Runner (22R) with 159K to get smogged yesterday and passed with flying colors.
HC=0, CO=0%, CO2= 14.5%

The brand new cat conv may have helped, as well as the tune-up I did.

Here's some tips for passing smog tests.

Thanks for the info.I don't know why the hydrocarbons alone are so high.Is it the EGR,cat,bad injector or what that causes the hydrocarbons to be high if they're not working?I got a 29 reading at 2500 rpms but a 1351 at idle.Does this mean the cat IS working. <img src="/forums/images/graemlins/confused.gif" alt="" />I want to be sure the components are operating correctly before I get too creative with altering things.If I fail marginally,then I'll go the gas additive,etc. route.

I checked the plugs and they are pretty dark.Looks like I'm running rich which would partially explain the high hydrocarbons.They were high-dollar bosch plat.+4.After all the negative stuff about them,I'm going with stock.Anybody know where to look next?

What does the inside of your oil filler cap look like?
Is your radiator full?
My high HC's were from coolant in the engine.

Thanks for the info.My radiator is good and haven't been losing any coolant.I changed the pcv,went with NGK plugs,cleaned the throttle body and my air filter is clean.I'm going to get a test done tomorrow to see where I'm at on the HC problem.Wish me luck.