Very Important Need Info Asap
Thread Starter
|
Elder User
Joined: Nov 2005
Posts: 575
Likes: 1
Very Important Need Info Asap
Now that I have your attention... Vehicle: my 94 F-150 XL 4x4 M5OD 4.9L with 201,423 miles
There is a metal tube that comes off of the second catalitic converter, and connects to a hose that is plugged into something the under hood diagram shows to be the main vaccum... I was looking through my haynes manual, and it mentions an Intergral back pressure transducer valve (BP). I am thinking this is what the tube is for. But what it is or does isn't the question. The question is, do I need it for my truck to run properly? I know I need my o2 sensor, but what about this tube thing?
And yes, I am re-doing my exhaust.
There is a metal tube that comes off of the second catalitic converter, and connects to a hose that is plugged into something the under hood diagram shows to be the main vaccum... I was looking through my haynes manual, and it mentions an Intergral back pressure transducer valve (BP). I am thinking this is what the tube is for. But what it is or does isn't the question. The question is, do I need it for my truck to run properly? I know I need my o2 sensor, but what about this tube thing?
And yes, I am re-doing my exhaust.
Senior User
Joined: Jul 2003
Posts: 311
Likes: 2
From: Nashville
This is going to be part of the EGR system, which does no harm performance wise if working properly, and can do some good in terms of lower idle temp. You can always weld in a fitting to the new exhaust and hook it right back up... most of those egr/ air tube fittings on the exhaust are close enough to a standard pipe thread you can use steel gas pipe fittings from the hardware store.
Senior User
Joined: Jul 2003
Posts: 311
Likes: 2
From: Nashville
On newer EFI 300's the computer "expects" the EGR system to be hooked up. Disconnecting it changes the intake charge and will mess with what the O2 sensor sees, and the computer will try to adjust by changing the mix. Without the EGR working detonation is more probable, so the computer will usually wind up retarding the timing too. In older vehicles where the EGR system was purely mechanical it could cause some driveability problems, most often rough idle, but in computer controlled vehicles it actually helps things run smoother.
Overall the EGR system helps the engine run cooler and a bit more efficient. The "recirculated" exhaust heats the intake charge inproving fuel atomization, and promoting a more complete burn at a lower temperature. Yea... hot gas making it burn cooler... doesn't make sense but it works. Since it's inert it slows the burn process so you don't get as big a peak in combustion temps. Forget the exact numbers, but peak temps are reduced by several hundred degrees.
Overall the EGR system helps the engine run cooler and a bit more efficient. The "recirculated" exhaust heats the intake charge inproving fuel atomization, and promoting a more complete burn at a lower temperature. Yea... hot gas making it burn cooler... doesn't make sense but it works. Since it's inert it slows the burn process so you don't get as big a peak in combustion temps. Forget the exact numbers, but peak temps are reduced by several hundred degrees.
Thread Starter
|
Elder User
Joined: Nov 2005
Posts: 575
Likes: 1
I have already figured out how I'm going to do this. I'm going with Hedman Headers, and I'll have a custom Y pipe made that has an o2 sensor bung and a tube for the back pressure sensor. Once I drop in my carb'd 300, I will just weld over the holes and be done with it.
Senior User
Joined: Jun 2003
Posts: 103
Likes: 0
What exactly is a back pressure sensor and what does it do? Is this signal read by the computer? How does the computer respond to the backpressure sensor?
Trending Topics
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
Thread Starter
|
Elder User
Joined: Nov 2005
Posts: 575
Likes: 1
Thats what I am trying to figure out too. My brother in law's 94 F-150 had no exhaust from in front of the o2 sensor back when he bought it, and it ran pretty good. I mean, it didn't even have the o2 sensor or the BP tube hooked up. The fact that my truck has 200,000+ miles on it, I want to keep it running as good as I can until I build my other engine.
Thread
Thread Starter
Forum
Replies
Last Post
Greyf100
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
3
Dec 8, 2010 10:39 PM