TOPIC: Gadgetguys with gas analyzers - EGR / DPFE test

In preparation for max vacuum on my soon to be grooved explorer I have been looking into block off of both the egr and iac and exactly what I need to do. IAC mods look every easy on an explorer as would blocking the EGR with a simialar flashing plate. As many of you are aware though ford moniotors EGR flow from the exhaust with fittings on the egr tube with an orfice in the middle. Because of that orfice in the tube the pressure is different on each side. Ford monitors those two pressures with the DPFE sensor which is a differential pressure feedback sensors (does not control, just reports the news to the PCM). The ECM controls when the EGR is to be turned on via vacuum and a vacuum relay.

So if you unplug the egr or cap it off the dpfe is sensing the same pressure on the each side of the orfice and your check engine light will come on.

Some focus guys posted a workaround to this check engine light issue without having to have a chip burned to eliminate egr function. See workaround #2 on this page:http://www.focushacks.com/mod/DPFE_Sensor_and_EGR_Information

Can someone who is grooved and has a gas analyzer at their disposal try this before and after ? I would if I had access to one but sadly I'm not there yet and in my area of the country there is no smog checking so none of the mechanics have one in my local area. Would be nice to see the affects on the state of tune of the vehicle (either positive or negative) at the tailpipe with real data.

A paintball tank with PCM/egr solenoid activated valve controlling nitrogen flow could also be plumbed into the dpfe and used as well but if workaround #2 works, that's awesome.

You can put a tee after the two small vac lines on egr tube plug intake port and run line back to exhaust pipe as this will fool the egr signal results no codes

after doing the groove egr is really not needed as exhaust temps go down means alot less nox gas

There is one other, more subtle aspect of this change that I would like to set on the table for your consideration.

As the EGR is located before the O2 sensor, it is drawing off precious HC's. I say "precious" because the higher the HC content at the O2 will cause an even greater reduction in fuel delivery.

Think about it!

OK, Ron, time for me to learn something again--you say that EGR draws off HC's...ya mean as in HC's going downstream into exhaust past open EGR pintle? I've always just figured exhaust gas would blow into intake air stream being at higher pressure/temp.

Could you amplify for me? Maybe I'm misunderstanding here...?

Thanks, Tracy

TracyG Gadgetman Reno

what hes saying is the unburnt fuel thrown in front of o2 and cat will cause ecu to see richer mixture ecu will then go lean on fuel trims timing causing better mpg.

anytime the engine can produce its owm rich hit the ecu will not throw code its when you try to change res or voltages the ecu is smart and will pick it up and throw code then open loop meaning fixed fuel control from ecu.

If you throw pcv gases into a catch all and have exhaust heating the container to steam them back to intake snout youll see increase in mpg due to thermal steam cracking of the heavys oil molecules and steam. You must get hot enough for steam cracking and the heat rising will only let the vapors in no liquid as heat rises.

I took the liberty of drawing a simple diagram showing the pressures and flows. This should clear up any misconception.




Based on this, you can see how the EGR in an Oxygen Sensor controlled fuel delivery system will necessarily reduce potential gains.

Thank You Ron and Dan!! you guys knocked my feeble brain's shifter back into gear for a moment!

Himac Research, Bruce McBurney (think I spelled that right from memory)...I read there years ago...the BB can thermal cracking of PCV crankcase gas/junk...that's Right!!

I gotta revisit all that stuff again. For now I just want ta keep the milkshake goo out of my intake stream.

I'm thinking we want the unburnt HC's in the exhaust at the O2, or rather we dont want to divert them back into intake via EGR. Visualizing the exhaust gas composition as a ratio or % of how much O2-to-everything else. If within limits we can shift the ratio of O2 lower in this gas then computer can "see" a "richer" mixture and lowers fuel trims...OK

Man that's what I dig so much about Ron and this site and all the Crackerjack Gadgetvolk...you guys make me THINK!

Rock'N'Roll, you guys!!

TracyG Gadgetman Reno

So Ron, can you simply plug the egr system to increase gains? Or will that throw a code?

My 2001 Silverado (the one I'm driving up on the 10-11th) has this EGR system on the 4.8

Here is a picture of the EGR from Intake to Canister then goes to the exhaust manifold (which is BEFORE the O2 sensor).

Tim, can you shoot the temp's on that EGR pipe going into that intake port? That pipe has insulation wrap on it? The location of this pipe in area where we did PCV re-route on the Suburban is tantalizing RE: this thread. Thanks for re-visiting this idea, been thinking of other stuff, Ron and Dan are amazing...!

Im gonna try to imagine how to build this, a metal can w/ BB's PCV gas from re-route directed into. Keep exhaust gas separate in heat exchanger spiral tube in can, or just vent into can let exhaust and crankcase gas mix? Might be best to keep exhaust separate from crankcase gas to keep function simple?

Maybe just cut that EGR feed pipe, re-route to the new can, then re-connect to pipe . Tryin' hard to imagine how to do it w/o any welding, I can't weld. Might need to insulate can/new EGR pipes to keep heat in, header wrap? Copper tubing/ brass compression fittings is simple enough, easy to work with, but can these stand up to heat and physical stresses to be reliable...?

this IS a worthwhile idea, can anybody else chip in w/ any ideas, knowledge? Materials, configurations, anything? Main thing hanging me up now is Materials. I have doubts whether copper pipe can withstand all various stresses and corrosion from exhaust. Factory EGR pipes are all steel pipe, but that's harder to work with in these diameters. Tryin' to think of a way for this w/o a lot of expensive fabrication and pricey stuff?

But this would put the Crud from the Crankcase to work for us, not just diverting it as I have been doing w/ air-oil separator.

Tracy G

stainless steel nat gas line flex works great and handles heat well. The right amount of exhaust and fuel to air ratio into intake the trims will hammer neg cutting back fuel and increase in mpg.

Here`s a test question for you all If I have exhaust from egr wide open heading to intake under vacuum what do I have in the center of pipe? vacuum or pressure trick question?

I want you to think and Ill tell you the answer in a few minutes. The answer will help you all get better mpg with the groove also. No need for all the add on electronics to fool the ecu as it will fool itself. We will outsmart its own parameters!!!!!!!!!!!! Dan Merrick

No responce? The answer is both when the valves open and shut causes a flutter or whart I call tension, this is where I named my reformer Fuel Under Tension Using Return Exhaust The first letters of each word FUTURE!!!!!!! If you were to take a ping pong ball and drop it inside the egr -vacuum tube the ball would flutter if this is gasoline droplets it will totally vaporize and by adding it in the proper spot with the proper air it will thermally crack the fuel and the tension will change the fuel molecular values then add a cataylyst such as plat or nickel or both shazamm you have a fuel cracker or onboard fuel refinery remember heat is also crucial and the unburnt fuel and water in exhaust is vital ecu sees Rich guess what ecu goes Lean. Timing will begin to adjust as the knock sensor will help teach the new fuel trims, remember vapors are different air to fuel ratio forget 14.7-1 100-1 sounds better. Fuel trims will be neg 25 long and short, hit it with hhhn and the cracked fuel will reform to cleaner and better burning and more powerful fuel. This will give you something to think about it does work and then the groove and turbulance in the reformer mpg has to go up!!!!!! The one key to getting it to crack perfect is the sweet spot in the egr tube this took me alot of years to find. Now its simple. Add the proper air amount on demand and youll have it.

Several have tried to copy and had no luck. Remember they change our fuel regularly so the cataylyst needs to be multiple or it will be inconsistent. Dan Merrick