smog pump
Elder User
Joined: Apr 2005
Posts: 726
Likes: 3
thats why i didnt pull the stuff off my 89 4.9 even though im not running a cat. its got the same air jet system. my 85 has the diverter valve but its carb and nothing ties into the head but rather it tied in after the carb. must easier to remove this from the system.
speaking on the emissions stuff greystreak you seem to know about it, i dont want to thread jack but i wanted to know about the blower fan on my CA truck that runs after the truck shuts off. its mounted on the pass fender and looks to pull air or provide it just above the injectors. although it doesnt actually connect there is just a pipe with holes in it there.
speaking on the emissions stuff greystreak you seem to know about it, i dont want to thread jack but i wanted to know about the blower fan on my CA truck that runs after the truck shuts off. its mounted on the pass fender and looks to pull air or provide it just above the injectors. although it doesnt actually connect there is just a pipe with holes in it there.
Junior User
Joined: Nov 2007
Posts: 86
Likes: 0
From: Upstate NY
smog pump
Originally Posted by greystreak92
So, making the gross assumption that were are referring to a non-modified 91 Bronco (gotta do this based on the screen name "mac-91"), the Thermactor system employs the Air Induction, Recirculation (A.I.R.) pump or "smog pump" for two reasons.
Introduce additional oxygen to the factory catalytic converter allowing it to heat above the temps achieved during the combustion cycle. This allows additional exhaust gasses to be burned off that cannot be in the normal combustion cycle. (Yes adding oxygen helps the temp rise because there is already enough heat present and when the oxygen is added, the gases that require the additional heat will ignite. Another source of combustion increases the heat).
Reason number two (and far more critical when you are dealing with the EEC-IV system) is that it provides additional fresh air into the exhaust ports in the heads for the same reasons and to help maintain the necessary oxygen levels in the exhaust so that the O2 sensor will function within the parameters it was designed for. Eliminating this input from the smog pump will adversely affect the operation of the O2 sensor and make tuning more difficult along with the fact that the system will no longer be able to control the flow of additional oxygen into the exhaust wich will effectively shorten the lifespan of the O2 (Oxygen) sensor. That odd contraption behind the passenger cylinder head with the hoses and vacuum lines known as the diverter valve handles the directing of fresh air from the pump to the cat and the heads. The TAB and TAD solenoids are the EEC-IV computer's (ECM) method of controlling this valve.
The problem with the arbitrary removal of PARTS of the system is the simple fact that they are so well integrated that it is impossible to remove any one without adversly affecting the rest of the system. Anyone who would argue this should try reading up on how the EEC-IV system really works.
Introduce additional oxygen to the factory catalytic converter allowing it to heat above the temps achieved during the combustion cycle. This allows additional exhaust gasses to be burned off that cannot be in the normal combustion cycle. (Yes adding oxygen helps the temp rise because there is already enough heat present and when the oxygen is added, the gases that require the additional heat will ignite. Another source of combustion increases the heat).
Reason number two (and far more critical when you are dealing with the EEC-IV system) is that it provides additional fresh air into the exhaust ports in the heads for the same reasons and to help maintain the necessary oxygen levels in the exhaust so that the O2 sensor will function within the parameters it was designed for. Eliminating this input from the smog pump will adversely affect the operation of the O2 sensor and make tuning more difficult along with the fact that the system will no longer be able to control the flow of additional oxygen into the exhaust wich will effectively shorten the lifespan of the O2 (Oxygen) sensor. That odd contraption behind the passenger cylinder head with the hoses and vacuum lines known as the diverter valve handles the directing of fresh air from the pump to the cat and the heads. The TAB and TAD solenoids are the EEC-IV computer's (ECM) method of controlling this valve.
The problem with the arbitrary removal of PARTS of the system is the simple fact that they are so well integrated that it is impossible to remove any one without adversly affecting the rest of the system. Anyone who would argue this should try reading up on how the EEC-IV system really works.
And on my 89 Bronco 5.0 the cross tube in the back of the heads has rotted out and is leaking, but the system hasn't thrown a CEL. Other then the exhaust noise it hasn't effected the engine or power output one bit.
Keep Em' Twistin' Bob B.
Bronco Stables: 89 thru 96 / XLT / Eddie B / BR II
Posting Guru
Joined: Apr 2006
Posts: 1,274
Likes: 1
hey Twisten,
On your 96, is there still a pulley at the pump location? I looked at the belt on mine (90' with pump) and I figured without a pump it would be about 2 and 3/4" shorter. I went to the auto-zone and asked for a belt for a 96 and it was longer than mine.
On your 96, is there still a pulley at the pump location? I looked at the belt on mine (90' with pump) and I figured without a pump it would be about 2 and 3/4" shorter. I went to the auto-zone and asked for a belt for a 96 and it was longer than mine.
Junior User
Joined: Nov 2007
Posts: 86
Likes: 0
From: Upstate NY
Originally Posted by helirich
hey Twisten,
On your 96, is there still a pulley at the pump location? I looked at the belt on mine (90' with pump) and I figured without a pump it would be about 2 and 3/4" shorter. I went to the auto-zone and asked for a belt for a 96 and it was longer than mine.
On your 96, is there still a pulley at the pump location? I looked at the belt on mine (90' with pump) and I figured without a pump it would be about 2 and 3/4" shorter. I went to the auto-zone and asked for a belt for a 96 and it was longer than mine.
Keep Em' Twistin'! Bob B.
Bronco Stables: 89 thru 96 / XLT / Eddie B / BR II
http://www.supermot<WBR>ors.net/vehicles<WBR>/registry/<WBR>15608
Posting Guru
Joined: Apr 2006
Posts: 1,274
Likes: 1
For everyone's information,
I was always under the impression that the pump added air to help burn unbernt gases in the cat.
I talked to the dealer and he told me the main reason for the pump is to dilute the exhaust. Ford was required (by EPA) to have only so many parts per million (ppm) of palutants. If thay up the total coming out of the pipe, the ppm's go down. He said this was counter productive because your gas millage goes down with the pump. So you are actually putting out more palution for a given amount of miles.
In any case, I found that a 910 length belt fits on without the pump pulley. You need only to remove the three bolts on the pulley, not the whole pump. I'm may try a gas millage run and see if it makes any differnce. I will report on here in a few weeks. I havent driven it yet, so I dont know about power. I suspect I wont be able to tell the differnce. I will say that after removeing the belt, I spun the pump and it does have a little drag. I would guess it would be a lot of drag turing at a couple grand. My "check engine light" has been on for years, so I cant address that question.
Of course this is for information only. I do not recomend removing the pump on a street ride.
I was always under the impression that the pump added air to help burn unbernt gases in the cat.
I talked to the dealer and he told me the main reason for the pump is to dilute the exhaust. Ford was required (by EPA) to have only so many parts per million (ppm) of palutants. If thay up the total coming out of the pipe, the ppm's go down. He said this was counter productive because your gas millage goes down with the pump. So you are actually putting out more palution for a given amount of miles.
In any case, I found that a 910 length belt fits on without the pump pulley. You need only to remove the three bolts on the pulley, not the whole pump. I'm may try a gas millage run and see if it makes any differnce. I will report on here in a few weeks. I havent driven it yet, so I dont know about power. I suspect I wont be able to tell the differnce. I will say that after removeing the belt, I spun the pump and it does have a little drag. I would guess it would be a lot of drag turing at a couple grand. My "check engine light" has been on for years, so I cant address that question.
Of course this is for information only. I do not recomend removing the pump on a street ride.
Junior User
Joined: Nov 2007
Posts: 86
Likes: 0
From: Upstate NY
smog pump
Originally Posted by helirich
For everyone's information,
I was always under the impression that the pump added air to help burn unbernt gases in the cat.
I talked to the dealer and he told me the main reason for the pump is to dilute the exhaust. Ford was required (by EPA) to have only so many parts per million (ppm) of palutants. If thay up the total coming out of the pipe, the ppm's go down. He said this was counter productive because your gas millage goes down with the pump. So you are actually putting out more palution for a given amount of miles.
In any case, I found that a 910 length belt fits on without the pump pulley. You need only to remove the three bolts on the pulley, not the whole pump. I'm may try a gas millage run and see if it makes any differnce. I will report on here in a few weeks. I havent driven it yet, so I dont know about power. I suspect I wont be able to tell the differnce. I will say that after removeing the belt, I spun the pump and it does have a little drag. I would guess it would be a lot of drag turing at a couple grand. My "check engine light" has been on for years, so I cant address that question.
Of course this is for information only. I do not recomend removing the pump on a street ride.
I was always under the impression that the pump added air to help burn unbernt gases in the cat.
I talked to the dealer and he told me the main reason for the pump is to dilute the exhaust. Ford was required (by EPA) to have only so many parts per million (ppm) of palutants. If thay up the total coming out of the pipe, the ppm's go down. He said this was counter productive because your gas millage goes down with the pump. So you are actually putting out more palution for a given amount of miles.
In any case, I found that a 910 length belt fits on without the pump pulley. You need only to remove the three bolts on the pulley, not the whole pump. I'm may try a gas millage run and see if it makes any differnce. I will report on here in a few weeks. I havent driven it yet, so I dont know about power. I suspect I wont be able to tell the differnce. I will say that after removeing the belt, I spun the pump and it does have a little drag. I would guess it would be a lot of drag turing at a couple grand. My "check engine light" has been on for years, so I cant address that question.
Of course this is for information only. I do not recomend removing the pump on a street ride.
the gases to pass emissions. Our lovely EPA gave standards to pass and our Automotive industry couldn't meet, thus came the Smog pump. The pump robs a few horses just for that fact. Any time you add a pulley it robs a few horses to get the job done. note: this why in racing they have a switch that turns off the ALT when racing, under yellow flag they flip the switch to charge the battery, Every pony counts.
Depending on the state you live in if the smog pump is removed it wont pass your state inspection. How ever, I removed the smog pump from my 79 F-100 and it didn't over heat the cat. And my 96 Bronco AND my 90 Bronco II doesn't have a pump on it and they have cats on them. So you could find a 96 5.8 that has a pulley that takes the place of the smog pump, and you wont have a belt issue. Or go to summit they have cheater for 5.0 ( Auto Specialties Smog Pump Eliminator Brackets: Bracket, Smog Pump Eliminator, Aluminum, Natural, Ford, Mustang, 5.0L, Kit) then plug off the holes in the back of the heads, and cap off the tube that goes into the cat. So other then emissions & state inspection the removal of the pump isnt going to effect the cat
Keep Em' Twistin'! Bob B.
Bronco Stables: 89 thru 96 / XLT / Eddie B / BR II
http://www.supermot<WBR>ors.net/vehicles<WBR>/registry/<WBR>15608
