Mechanically Disabling the EGR Valve
Originally, I suggested blocking off the EGR valve to improve power and increase gas mileage then I changed my mind and enabled it. Well, after about 3/4 of a tank of gas - it's disabled again. It just hurts performance and all around driveability too much to enable it! Disabled, it provides about a 5% increase in both hp and gas mileage from what I can tell. The engine runs better and has better acceleration without the egr.
The EGR (exhaust gas recirculation) valve's job is to introduce exhaust back into the intake manifold to reduce emissions at the expense of power and gas mileage. The previous link does a good job of describing its operation.
This seems to be utterly stupid especially because exhaust gases are added after the fuel/air mixture is determined. It seems to be defeating the purpose of a proper air/fuel mixture!
Now, my goal is to increase fuel efficiency so that I use less gas - consequently reducing the pollution to the atomosphere. So far with all the mods (including this one), I've increased my highway mileage dramatically and increased the engine's power!
The EGR valve at the back of the engine.
The EGR valve is located at the back of the throttle body. It has a pipe that runs from the exhaust manifold over the head next to the firewall to the EGR valve. Ideally, you would like to disconnect and block off that pipe but you'll find that it is seized and rusted in place. A big nightmare to get it off. The alternative is to block off the EGR to throttle body passage - that's a lot easier. Just takes an easily made blocking plate made out of a piece of sheetmetal you have lying around. If you can't make your own EGR blocking plate, the Detail Zone sells inexpensive blocking plates (link courtesy of jkmustang - thanks!).
The exhaust pipe from manifold to EGR valve
Gasket on top, sheet metal blocking plate on bottom
There's two bolts (10 mm head) that hold the EGR valve onto the throttle body. The top bolt is easy to get to but the bottom is very awkward. Disconnect the throttle body position connector from the driver's side of the EGR valve to give yourself room. I used a box end 10 mm wrench to unscrew the bottom bolt.
Undo two bolts and slip in new gasket and blocking plate
I purchased a new EGR valve gasket for $4.00 and used it as a template for making a blocking plate. Put the new gasket against the throttle body and the blocking plate on the EGR side. Bolted it all together. Took less than an hour! The engine runs quieter and smoother. I have a little more power and will find out if the gas mileage improves with the next tank of gas.
Some Final Words
Aaron K. sent me an email with some good questions, here's my response:
Option #2 - Fooling the ECU using an EGR Simulation Circuit
If you don't feel like using a block off plate then you can build this EGR simulation circuit. Just to clarify, you can defeat the EGR either with a block-off plate or using this circuit. There's no need to do both. The EGR simulation circuit fools the ECU into thinking that the EGR is working when in actual fact, it is disconnected, shut off and no exhaust gases can get into the intake manifold.
There are two parts to the EGR system and here's how they work electrically:
I received an email from James- ASE Master Tech and he says:
Just thought I'd give a little info on the EGR page in the 2.3 article. You wrote that by you blocking your egr you gained power and economy. If your egr is working properly, then you should not have noticed ANY gains. The egr only operates during cruise conditions. It does not operate at idle because idle quality would be greatly affected. It does not operate at full throttle because Ford knew you want full power when you put the pedal to the metal. The reason they do it at cruise is because it has very little effect on performance when you are cruising down the freeway at a light load. when you smash down on the accelerator, the egr shuts off. In my 94 ranger the egr uses a DPFE (Delta Pressure Feedback EGR). In that, there is an orifice inside the tube that goes from the manifold to the throttle body. There is a silicone tube on each side of this orifice that goes up to what looks like a map sensor with two lines going to it. When the egr starts to operate, there is a pressure difference within the tube on either side of that orifice. This is how that 'map' sensor verifies that the egr has proper flow. In addition, when that sensor sees flow of the egr at cruise the computer knows that it is an inert gas and backs off fuel to keep a proper AF ratio, lower NOX, and save fuel. So if you noticed any power increase from blocking off your EGR it was not working properly. It most likely had a sticking valve that was allowing exhaust gasses back into the intake at all RPM. This would greatly affect power.
It's good to hear an alternative "argument" about blocking off the EGR valve. Unfortunately, I don't have the truck anymore to follow up and check the EGR valve.
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