Do true duals cause problems with EFI..?
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Senior User
Joined: Mar 2002
Posts: 117
Likes: 2
Do true duals cause problems with EFI..?
When I install a set of Thorley headers on my '96 F-250 (MAF injection 460), I'm considering adding a second 3" exhaust on the left side making for true duals all the way back.
I've seen some mention that running dual exhausts with the EFI engines makes the computers unhappy...This concerns me...Anyone know what the real issues are, if any, or is this just a legend? Is a crossover pipe to tie the L+R pipes together necessary, as I've also seen some doing?
FWIW, the truck has two oxy sensors, one a foot or so down from the left engine manifold and a second one at the exit of the existing catalytic.
Thanks in advance for any comments...
I've seen some mention that running dual exhausts with the EFI engines makes the computers unhappy...This concerns me...Anyone know what the real issues are, if any, or is this just a legend? Is a crossover pipe to tie the L+R pipes together necessary, as I've also seen some doing?
FWIW, the truck has two oxy sensors, one a foot or so down from the left engine manifold and a second one at the exit of the existing catalytic.
Thanks in advance for any comments...
Elder User
Joined: Jan 2000
Posts: 966
Likes: 2
From: Crooked River Ranch, OR
Do true duals cause problems with EFI..?
You can run "true-duals" but you need to keep your O-2 sensors since they fine tune your air/fuel mixture. Just have the muffler shop install your old O-2 bungs into the new pipe.
Senior User
Joined: Jan 2002
Posts: 201
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Do true duals cause problems with EFI..?
A crossover pipe is recommended also. Since your firing order isn't 1,2,3,4,5,6,7,8, whenever an even pair or odd pair of cylinders fire back to back, you'll get high exhaust pressure on that side which defeats the purpose of the dual exhuast to lower the back pressure.
Freshman User
Joined: Dec 2001
Posts: 32
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From: USA
Do true duals cause problems with EFI..?
I ran true duals on my 88 460 with 2 1/4 inch pipe, 18" glass packs, and no cats. It sounded really really good, and run over 100k that way with no proplems. The only reason I sold the truck was that it had lost some power, due to the fact that it pulled a trailer for 90% of it's 280,000 miles. Hope this helps, Mason
