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Discussion Starter · #1 ·
If I were to take off the air pump and plug the hoses up that inject air into my manifolds. Would this affect my gas mileage and performance? I bought a new TAD and TAB selnoids and I cannot get the air bypass/control valve to work. It hold vaccum and if I put a vaccum line on it from a straight vaccum source it will work but if I leave it on then the truck constantly backfires. I'm ready to just say f'*@k it and take the emmissions off but I don't know if that will affect performance at all. I don't have any cats on my exhaust just muffler.

Backyard Builder-If I ain't drivin it I'm under it!
 

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Do you still have an oxygen sensor? When you ran the vacuum straight, it caused the air to blow straight into the exhaust, thinning it out. This would have confused the HEGO and it would have tried to adjust the fuel mix. That's probably why it was backfiring. How do you know the bypass/diverter valve isn't working? Have you tested it the way Haynes describes? You should be able to get one from Ford or a junkyard.

Steve 83 Bronco 4.9L
Build it; Don't buy it...
 

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Discussion Starter · #3 ·
Ya I have a new bosch O2 sensor when I got my exhaust done.
I remember before when i had the 5.0 there was a vent for it well there is a vent for it also with the 5.8. and when i would pull the throttle back it wouldn't vent. When it was at idle or coast then it vents. but on the 5.8 I have it always vents even at WOT. unless of course I bypass the TAD & TAB. Then as I said it will backfire. I figured that the extra air had something to do with it. Maybe If I Disconnect the O2 sensor. I don't think that would work either. The air-bypass/diverter valve combo is from the 96 motor. I never thought of keeping the old stuff. Also I remember that the the 96 only had 1 TAD no TAB or vice-versa. But since I had to use my 90 wiring I assumed that I have the connections for both TAD & TAB so I better use them. Maybe not?? This is driving me crazy.
On a different note- I notice you have the air cleaner box off a 5.0 EFI, still have it ? This open air element just isn't cutting it in the mud. I can't find one around here.

Backyard Builder-If I ain't drivin it I'm under it!
 

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If I remember your swap, you used all the intake & exhaust from the original engine, right? If so, you need to quit thinking of it as a '96 engine and think of it strictly as a '90: hook up everything the way it should be for a '90 5.8 and it should run fine. Only AFTER it runs right would I start thinking about modifying stuff. Try to get the right air valve for a '90, use the TAB & TAD, and route all the vacuum lines the way they go on your original vacuum map.

I think I have a couple of air boxes - one mounts to the fender for any size gas engine '87-97, and the other came from an '84 5.0L & mounts over the L valve cover. Both are on this page but in different photos.

Steve 83 Bronco 4.9L
Build it; Don't buy it...
 
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