89 Bronco II 2.9l emission failure ?????

[LNorvell]

I have an 89 ford bronco II that failede the low speed emission test. The hydrocarbons were over the limit, but they were below the limit on the high speed test. I was told to run fuel treatment through the fuel system, change plugfs, wires and dist cap/rotor. All was done. Tookit in for 2nd test and high speed hydrocarbons dropped while low speed hydrocarbons increased dramatically. Does anyone have an idea what I may need to check/change to pass emessions testing. Any help is appreciated.

 

[MrShorty]

One time mine failed emissions due to a clogged air filter (the previous years deer hunt was real dry and dusty).

Is the engine running well otherwise? Have you tried pulling codes or anything? It seems like high hydrocarbons would indicate that it is running a little rich or not burning completely. You might check things related to fuel mixture (like fuel pressure) to see if there is anything off.