Rough Idle v-10
FTE Leadership Emeritus
Joined: Jul 2002
Posts: 42,561
Likes: 423
From: Long Island USA
That's strange... sounds like the fuel regulator diaphragm is cracked.
If you have the right vacuum at idle (15-17 inches), pressure should be at that 28-30 at idle.
When you decelerate, and produce even more vacuum, upwards of 20 inches, then you get the required 28-30 lbs.
Not to say that the fuel pressure regulator is bad, but I'd check the vacuum levels to see what they are at idle. Report back
If you have the right vacuum at idle (15-17 inches), pressure should be at that 28-30 at idle.
When you decelerate, and produce even more vacuum, upwards of 20 inches, then you get the required 28-30 lbs.
Not to say that the fuel pressure regulator is bad, but I'd check the vacuum levels to see what they are at idle. Report back
Post Fiend
Joined: Jan 2002
Posts: 5,859
Likes: 7
From: USA
Art ,I believe the fuel pressure should be 35-40 constant,nothing below that.
underload or idle.
thanks for the welcome back,a trip to michagan was the cause.
Again not saying rough idle is caused by fuel pressure but its a basic engine chk that should be done.
Most people forget about the basic engine chks before changing parts.
fuel
ignition
compression
etc.
Rich
underload or idle.
thanks for the welcome back,a trip to michagan was the cause.
Again not saying rough idle is caused by fuel pressure but its a basic engine chk that should be done.
Most people forget about the basic engine chks before changing parts.
fuel
ignition
compression
etc.
Rich
FTE Leadership Emeritus
Joined: Jul 2002
Posts: 42,561
Likes: 423
From: Long Island USA
Originally Posted by FortyFords
Art ,I believe the fuel pressure should be 35-40 constant,nothing below that.
And here's Ford's specs from the book:
Fuel Pressure ³
ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ ÄÄÄÄÄÄÄÄÄÄÄÄÄÄ´
³ 5.4L and 6.8L Gasoline Engine ³ 193-310 (28-45) ³
³ Running kPa (psi) ³ ³
ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÅÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ ÄÄÄÄÄÄÄÄÄÄÄÄÄÄ´
³ 5.4L and 6.8L Gasoline ³ 240-310 (35-45) ³
³ EngineÄKey On Engine Off kPa ³ ³
³ (psi) ³ ³
Notice the higher spec for key-on/engine-off? No vacuum to the regulator, so it goes to full.
At idle, it's usually 28-30 because vacuum is high.
At least, that was other MPFI Ford's I've worked on. I haven't checked my V10. However, we did have someone go through the key-on/engine-off and key-on/engine-idling difference and they had about 30 and 40 respectively.
Senior User
Joined: Mar 2007
Posts: 440
Likes: 0
From: Montana
Mine has the same problem. I think I may have just found the problem. I checked the pcv valve and it seemed fine. I followed the hose from the pcv to the intake manifold and found a huge hole in the hose. it was so big that I could put my finger in it. I am going to replace the hose and reset the computer tomorrow and see if it helps. Its gotta help something. Does anyone know where I can get parts like this shipped out fast if the dealer doesn't have it. Inside the pcv hose was very oily. Is this normal?
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New User
Joined: Feb 2004
Posts: 22
Likes: 0
From: Pittsburg NH
The problem is not solved yet. I've been real busy lately.
However it does smell like its running rich.
the first time it did something similar a couple years ago it was a hole in the pcv hose, but not this time.
I bought my hose from the dealer but had to order it, and of corse the dealer had never heard of it happening before.
Keith
However it does smell like its running rich.
the first time it did something similar a couple years ago it was a hole in the pcv hose, but not this time.
I bought my hose from the dealer but had to order it, and of corse the dealer had never heard of it happening before.
Keith
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New User
Joined: Jul 2007
Posts: 2
Likes: 0
I was able to fix mine today. 2 holes in the PCV tube right under the throttle body. One at the 90 degree bend and one closer to the intake. I made the new piece longer so that it does not have such a bend in it and I used heater hose. It looks like it will work better than factory. Please let me know if you find out what is going on with yours.
Thanks
Tom
Thanks
Tom
Lead Driver
Joined: Sep 2003
Posts: 5,844
Likes: 6
From: Albuquerque
Originally Posted by Budman1962
I fixed mine today with heater hose. Idles smooth again. But the heater hose is touching the intake manifold. Will this burn the rubber? Or is it heat resistant enough.
Budman
Budman
Nice job!
biz
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New User
Joined: Feb 2004
Posts: 22
Likes: 0
From: Pittsburg NH
When I first tried repairing mine a couple years ago I used heater hose and when it heated up it got too flexible and collapsed. So I ended up using a couple small hose pieces with a piece of 1/2 inch elect conduit for the bend untill my ford part came in, it got me by.
Keith
Keith
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New User
Joined: Feb 2004
Posts: 22
Likes: 0
From: Pittsburg NH
I know its been a while but I finally got a chance to spend more time on the truck. Well I decided to check the EGR valve by pulling it off, I removed it and when shaking it I could hear it rattling inside. Its saturday later in the day here and no parts stores open so I decided to open the crimped seam to see inside. The metal portion of the rubber diaphragm was partially broken inside and would not hold onto the valve stem. Temporary fix for the w/e but I crimped the metal to the stem and re crimped the edges of the housing back together, its all good for now, will order another monday.
Thanks for everyones help
Keith
Thanks for everyones help
Keith
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