Question about 1981 Ford Bronco
We have a 1981 ford bronco full size. We have failed emissions twice. The hc is 451 and the co is 790. We wanted to check the codes but the check engine light does not come on at all. Not even when turning on the igniton. Where is the check engine light supposed to be? The previous owner painted over the dash and some of the lights. Any input on the emission trouble? The engine is a 1988 302. Thanks
Look behind the motor, next to the firewall. There's a vacuum check valve that keeps the air gulp pump from pressurizing the crankcase. Mine was shot; had the same symtoms. Also, make sure that the EGR valve is closing at low idle.
You don't need an engine light to check the codes. First, do a KOEO (key on, engine off), but, let me tell you, when this happened to me (1986 Full size with 302 EFI, multiport injection) NOTHING showed up. No one, not Ford, not emission specialists, nada, knew the vacuum check valve existed.
By the way; are you getting motor oil in the air filter housing?
Posted on Jun 28, 2009
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Posted on Jan 02, 2017
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