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351w EGR Questions

O'Rattlecan

O'Rattlecan

Redneck Prognosticator
26,687
797
Belton, MO
Well, this fall I'll be getting a round of new tires, and while I was at it, I thought I'd go ahead and do the header upgrade. There are headers with the EGR hookups, so if my question has an answer I don't like, I can always go that route.

What is involved in removing the EGR system in the 351w in my 1994 F-150, and what consequences are there in removing it?

Ryan
 
blacksnapon

blacksnapon

Moderator
Staff member
9,461
301
waynesville,mo.
The egr in gas jobs is a lot more important than diesel. It helps keep down pre-ignition so you can advance timing. My suggestion, is unless you're going with monster horsepower, keep the egr valve.
 
O'Rattlecan

O'Rattlecan

Redneck Prognosticator
26,687
797
Belton, MO
good to know. I had always heard about piston 8 burning up because of it, so I thought it might be a good thing. In this case I guess not. I'll just keep my eye out for headers with the EGR hookup.

Ryan
 

Bob Ayers

North Carolina Chapter member
1,474
111
Durham, NC
I agree, keep the EGR!!
 

Bob Ayers

North Carolina Chapter member
1,474
111
Durham, NC
O'Rattlecan said:
I do wonder though, guys. How does using the egr help it be able to have advanced timing? I guess I don't get it.

Ryan
Click to expand...


EGR lowers combustion temperatures, allowing ignition timing to be advanced further without pre-ignition.
 
blacksnapon

blacksnapon

Moderator
Staff member
9,461
301
waynesville,mo.
Bob's got it! It makes the incoming mixture less volatile. Manufacturers have been making camshafts that have lifts and durations that take into consideration advanced timing made possible by egr function. So you can get an idea how just disableing the egr valve with no other modifications is kind of futile.
 
andym

andym

Real men are fanatics
604
33
Roseville, CA
The piston #8 problems in the windsor engines are because of the routing of the PCV line, not the EGR, I've always heard.

I would also be less concerned about removing the EGR for performance reasons, as it only puts exhaust gas into the intake during partial throttle, i.e. cruising around town. Once you hit the gas, the valve closes up. It sure helps to increase your gas mileage though. I notice a couple MPGs difference with the vacuum line plugged.
 
Skandocious

Skandocious

Post Whores Make Me Sick
19,076
655
California
I posted on your 351W headers thread about this. If there are any sets of headers that you want which DON'T have the hookup for the EGR (and don't forget about the bungs for the o2 sensors), you can always have an exhaust shop weld these things on for very cheap, this is what I am doing with mine.
 

eco

646
12
The #8 problems are from the PCV dumping everything down cylinder #8.

As far as removing EGR, as long as the computer recieves an EGR closed signal all the time, pe-ignition wont be a problem. When the computer thinks the EGR is flowing (due to the position sensor and thus assumed flow...thats all the computer goes by), the timing advances an additional 10*. If the computer thinks EGR is flowing and it really is not, then you get pre-ignition due to all that extra advance without the EGR present to cool the combustion temps. If the computer knows that the EGR is closed due the position sensor (or resistor to take it's place better yet), the computer will never give that extra 10* of advance.

EGR closed signal at all times = EGR function disabled (w/ EEC-IV) = no additional 10* advance = no problems with EGR removal!! The only real advantage here is less clutter, less to fail and a cleaner intake plenum and manifold. The EGR causes carbon build up galore!!

If you just block the EGR valve off and leave everything else intact, then you will have a problem. Remove the system properly, then you wont have any problems.
 
Old_Paint

Old_Paint

Old guy with old cars
225
29
Alabama
I've read much, and understand the reasons for the failure on #8 due to PCV gases (oil vapor in the cylinder). What I don't understand is WHY Ford put it on the back of the intake. That's of little relevance, though.

I would think that putting the tap somewhere close to the same approximate area as the EGR would be the better idea. That would distribute PCV gases equally to ALL cylinders. Unforutunately, it may also cause a lot of crud build-up in the plenum, depending on how advanced ring/valve guide wear was. I've also read of folks using in-line separaters for the PCV to clean some of the atomized oil from the vapors. That should mitigate some carbon build-up on the rings/pistons/heads. I'm going to study up on relocating the PCV, and may do this on a summer project. My only concern is how it's going to affect vacuum signals to the MAP sensor. The PCV is a "designed" intake leak used to draw the gasses off the block. I'm just not sure how this is going to work with it being relocated. I'll have to make sure to use some sort of threaded fitting so I can plug it off again if it causes adverse results.

As far as the EGR being capped off, I guess it's possible it will cause ping, but it never did on mine. I ran at least 3 tanks of fuel through my truck (cheap stuff too) hunting vacuum leaks with the EGR blocked off at the plenum. Even at interstate speeds, I never heard it ping once. The advance of the timing will probably affect it more than the blocked off EGR. The O2's are going to sense the richer mixture due to no EGR mixing, and the EEC will cut back on the injectors some. That will help, but not as much as having the EGR in place and functional. All this said, my timing is at the base 10* recommended for the engine.
 
Last edited:

eco

646
12
Old_Paint said:
I would think that putting the tap somewhere close to the same approximate area as the EGR would be the better idea. That would distribute PCV gases equally to ALL cylinders. Unforutunately, it may also cause a lot of crud build-up in the plenum, depending on how advanced ring/valve guide wear was. I've also read of folks using in-line separaters for the PCV to clean some of the atomized oil from the vapors. That should mitigate some carbon build-up on the rings/pistons/heads. I'm going to study up on relocating the PCV, and may do this on a summer project. My only concern is how it's going to affect vacuum signals to the MAP sensor. The PCV is a "designed" intake leak used to draw the gasses off the block. I'm just not sure how this is going to work with it being relocated. I'll have to make sure to use some sort of threaded fitting so I can plug it off again if it causes adverse results.
Click to expand...

Mr. Paint, there is an easy way around all of this. You could get the benefit of the air passing through the crank case without the massive crud build up in the plenum.

Just get rid of the whole PCV system and install a road draft tube. No maintanence, effective and no down side to it aside from pollution. Modern diesels use this method as did the auto makers back in the old days and it is proven to work well.
 

95F350XL

Master Junk Tech
3,000
49
Belle Mead NJ
When I installed my LT's I removed all of the EGR stuff. All thats left is the valve with the tube capped off, and the air pump with no lines going to it. I get the same MPG with it gone, as when I had it. Truck runs great and I still pass NJ inspection. As long as I have the cat on. I know some of the less GVRW trucks had more emissions stuff then the higher ones. My buds bronco had so much you could barly see the right side of the engine bay. And he was always like where are your lines. I never had em.
 

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