Emission Troubles

[spitdriver]

First things first.. This is my first (of many I hope) post to this group. I appreciate all the help you could give me and I will try to pass on any info I may have that is of use to anyone.

My '91 Bronco has been to the shop twice for it's every two year emission test and failed both times. The tech at the shop the second time told me it was running way rich and the the air from the air pump that is supposed to be injected into the system when running is being cast overboard through an outlet in the system. He goes on to say that it could be a bad solinoid that is causing it.

Anyone have any ideas??

The outlet is a silver canister that sits on the left side (as you look at it) of the engine bay. I traced it around and got nowhere near anything that looked like a soliniod.

I'm going to take it back for some diagnostics but I figured I look here first.

Thanks

 

[Seabronc]

You are looking for the TAB (Thermactor Air Bypass) solinoid. It and it's companion solinoid TAD (Thermactor Air Diverter) saolinoid. Theya re located on the right side of the engine about 2/3 of the way from the front probably mounted on abracked that is attached to the valve cover. They probably don't fit your picture of a solinoid, they aren't as large as the starter solinoid.

Good luck,

>-

 

[Seabronc]

Also, those two solinoids control vacuum lines. I would check the vacuum line that controls the bypass valve. If it is broken or has a serious leak, the air will definate dump overboard. So I would suspect the vacuum supply to the solinoid, the vacuum line from the solinoid to the bypass valve, or the solinoid itself. The latter two being the most suspect as the supply line feeds other stuff.

>-

 

[spitdriver]

Whoo hoo!! Now it does pass Alaska IM test. The mechanic at my local shop shot it down to a faulty fuel pressure regulator that was causing the engine to run rich in turn making the computer adjust for the problem and dumping the air from the pump overboard... They fixed it up and it passed fine! /emoticons/[email protected] 2x" width="20" height="20" />

 

[American Rebel]

I guess in Alaska my bronco would fail for a faulty EGR valve.... LOL

Do bronco's have dual catalytic converters? I was wondering since I don't have a muffler, and it isn't loud at all....

 

[mbtech2003]

mine "had" two. i cut the second one off. still passes fine and mass needs to meet calif. requirements

 

[American Rebel]

Is it worth cutting the second cat off, any difference in sound?

 

[mbtech2003]

yes and it makes the tone more deep with the flowmaster muffler that i have :wacko: