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Discussion Starter · #1 ·
I need somebody that knows what they're talking about to give me some advice, so if you have no idea about what will make my engine run better, please don't act like it.

1995 full size Bronco
5.0 ho from a 1995 mustang gt
GT40p heads, stock truck intake, blocked off egr port from the heads to the lower intake. Stock explorer drivers side manifold & 351w passenger manifold(in case anybody was wondering what I did about exhaust manifold) block-off gasket with the egr valve. Speed density setup, looking for MAF setup.

All I'm wanting to know is if I leave the egr valve, AIR D & AIR B & EVR(i think that's the name of it) plugged in, will it negatively affect how the engine runs? My CEL went off and the ECM is adjusting parameters and whatever else it does, but will it hurt me any? As far as fuel mileage, air/fuel ratio, etc, everything else goes, should it run correctly? Or what do I do to fully delete these components from the system? I can buy a dummy sensor or whatever else, but I dont have an obd1 tuner or anything like that to help me out here. Engine trouble codes were 326, 327, 552 & 557. CEL went off after I plugged these sensors back in.
 

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I need somebody that knows what they're talking about to give me some advice, so if you have no idea about what will make my engine run better, please don't act like it.

1995 full size Bronco
5.0 ho from a 1995 mustang gt
GT40p heads, stock truck intake, blocked off egr port from the heads to the lower intake. Stock explorer drivers side manifold & 351w passenger manifold(in case anybody was wondering what I did about exhaust manifold) block-off gasket with the egr valve. Speed density setup, looking for MAF setup.

All I'm wanting to know is if I leave the egr valve, AIR D & AIR B & EVR(i think that's the name of it) plugged in, will it negatively affect how the engine runs? My CEL went off and the ECM is adjusting parameters and whatever else it does, but will it hurt me any? As far as fuel mileage, air/fuel ratio, etc, everything else goes, should it run correctly? Or what do I do to fully delete these components from the system? I can buy a dummy sensor or whatever else, but I dont have an obd1 tuner or anything like that to help me out here. Engine trouble codes were 326, 327, 552 & 557. CEL went off after I plugged these sensors back in.
So there's a lot of shadetree mechanics who end up disconnecting all the emissions stuff on EFI engines, simply because they are too incompetent to fix them. Fact of the matter is <assuming> it is all working correctly, having the emissions gear hooked up will have almost zero effect on performance. A lot of the prejudice against emissions controls dates back to the bad old days when carburators were saddled with a bunch of poorly engineered emissions stuff to hide the fact that carbs are shitty at metering fuel accurately. Add to that ignoramuses who think they are "rebels" by tearing out the emissions and slapping a Punisher skull sticker on the tailgate, you have a lot of bad info out there.
That being said, if you have a modern replacement catalytic converter, there's really no need for the Thermactor air injection system (smog pump, piping, and TAB/TAD solenoids, and vacuum lines), so yeeting all that stuff is fine, just leave the solenoids plugged in to keep the EEC happy, and plug the vacuum ports. Since the EEC is looking for the EGR and it is pumping stuff into the engine itself, you are usually better off keeping it intact and working unless you are going with a custom EEC.
 

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1995 Ford Bronco
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Discussion Starter · #3 ·
@Rspasoje, thank you for the honest and straightforward answer! I'm trying to be more than just a shadetree mechanic here, just educating myself a little further. So hear me out here.
So the egr, recirculates exhaust gas in order to keep the nitrogen oxide levels to a minimum. But, that raises combustion temperatures, causes carbon buildup over time, especially as the system's components become tired & worn.

That's the bad. Correct me if I'm wrong, but here's what I'm thinking and the logic behind it from my general understanding of engines; unblocking the egr port between the front two and rear two intake port of heads, Will allow the same air from the intake to flow through the passages, right? What would happen if I unblocked those two ports? I'm guessing that would bring cooler air into the passages instead of exhaust air. Which, in turn, would lower combustion temp., fuel burns longer & more efficiently with the cooler air so it wouldn't be working half as hard to make more power, efficiently. Right? Now what if I unblocked the egr valve and run the hose that comes out of it into one of the throttle body intake air hoses?
Or instead of that, what if I ran a hose from the egr valve to behind the grill, with an air filter of some sort at the end? Would that make it act as a ram air system by bringing in cooler air directly into the upper intake or would it just act like a big ass vacuum leak? If it would act like a big ass vacuum leak, what if you used the smog pump to work like an air compressor? It would compress cold air, shoot it into the intake, with the regulation of the egr valve, but throw a T in the hose between the smog pump and egr valve with a check valve on the T side so that it don't build up too much pressure and blow the hose. All I'm hoping to do is optimize how this engine runs in every way I can. It don't run quite like I want it to just yet. Of course, I have a few other problems that need tended to, but I'm focused on this one at the moment. If that just sounds like a bunch of crazy talk with no logic, correct me, but if everything operates like I think it does, I could possibly be onto something lmao.
 

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First off, what PCM are you using? Your 95 would be MAF if it was a 5.0 originally. As for your ideas about the EGR and thermactor, you're basically talking about a lot of unmetered air in the system. Any incoming air needs to flow throw the MAS. Also, the thermactor isn't a compressor, just an air mover.
 

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Discussion Starter · #5 ·
I thought only the California emissions models had the mass air flow? Cause I've only seen one mass air f150, but mine is speed density. My bronco was made in 06/94 its considered a 95 on the title
 

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EGR is used to reduce combustion temperature to prevent from making too much NOx. A lean mixture will burn hotter. If you fool the computer by brining in oxygen when it is expecting a non-oxygen stream, it will be very lean and burn very hot. An SD system isn't smart enough to adjust for airflow; it looks at manifold air pressure (and other things, but volumetric airflow not one of them) to infer an air flowrate and corresponding injector pulse time.
 

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1986 Eddie Bauer 5.0EFI AOD Full length headers Y pipe into single 3" Magnaflow 3" factory exit
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My EGR was unhooked when I bought my Bronco. We are a non emissions state so it didnt really matter if i had it hooked up or not, but when going thru the truck & fixing all of the code related things, one of the final items was the EGR.

I figured even tho I didn't need it, I would get it working, just to see what difference it made, as it was only a bad $15 solenoid. Once I got it working, the truck ran noticeably better at cruising speed & fuel economy was definitely improved as well.
 

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95 5.8L MAF XLT, Hedman Shorties/MF SS Y & Muff, E4OD, Man hubs, KYB Quads, 31x10.5x15, 304K miles
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@Rspasoje, thank you for the honest and straightforward answer! I'm trying to be more than just a shadetree mechanic here, just educating myself a little further. So hear me out here.
So the egr, recirculates exhaust gas in order to keep the nitrogen oxide levels to a minimum. But, that raises combustion temperatures, causes carbon buildup over time, especially as the system's components become tired & worn.

That's the bad. Correct me if I'm wrong, but here's what I'm thinking and the logic behind it from my general understanding of engines; unblocking the egr port between the front two and rear two intake port of heads, Will allow the same air from the intake to flow through the passages, right? What would happen if I unblocked those two ports? I'm guessing that would bring cooler air into the passages instead of exhaust air. Which, in turn, would lower combustion temp., fuel burns longer & more efficiently with the cooler air so it wouldn't be working half as hard to make more power, efficiently. Right? Now what if I unblocked the egr valve and run the hose that comes out of it into one of the throttle body intake air hoses?
Or instead of that, what if I ran a hose from the egr valve to behind the grill, with an air filter of some sort at the end? Would that make it act as a ram air system by bringing in cooler air directly into the upper intake or would it just act like a big ass vacuum leak? If it would act like a big ass vacuum leak, what if you used the smog pump to work like an air compressor? It would compress cold air, shoot it into the intake, with the regulation of the egr valve, but throw a T in the hose between the smog pump and egr valve with a check valve on the T side so that it don't build up too much pressure and blow the hose. All I'm hoping to do is optimize how this engine runs in every way I can. It don't run quite like I want it to just yet. Of course, I have a few other problems that need tended to, but I'm focused on this one at the moment. If that just sounds like a bunch of crazy talk with no logic, correct me, but if everything operates like I think it does, I could possibly be onto something lmao.
Brannon You have the EGR theory/function not fully understood. I would recommend you do a search online about EGR Systems purpose/function/theory and read up on it and you will see where you are going astray on your above post. I could go into a long decertation on this subject but I'm sure it is explained much better then I would do. The EGR is not hurting the full power production of an engine it just works under certain conditions when higher Vacuum signals are available.
 

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@Rspasoje, thank you for the honest and straightforward answer! I'm trying to be more than just a shadetree mechanic here, just educating myself a little further. So hear me out here.
So the egr, recirculates exhaust gas in order to keep the nitrogen oxide levels to a minimum. But, that raises combustion temperatures, causes carbon buildup over time, especially as the system's components become tired & worn.

That's the bad. Correct me if I'm wrong, but here's what I'm thinking and the logic behind it from my general understanding of engines; unblocking the egr port between the front two and rear two intake port of heads, Will allow the same air from the intake to flow through the passages, right? What would happen if I unblocked those two ports? I'm guessing that would bring cooler air into the passages instead of exhaust air. Which, in turn, would lower combustion temp., fuel burns longer & more efficiently with the cooler air so it wouldn't be working half as hard to make more power, efficiently. Right? Now what if I unblocked the egr valve and run the hose that comes out of it into one of the throttle body intake air hoses?
Or instead of that, what if I ran a hose from the egr valve to behind the grill, with an air filter of some sort at the end? Would that make it act as a ram air system by bringing in cooler air directly into the upper intake or would it just act like a big ass vacuum leak? If it would act like a big ass vacuum leak, what if you used the smog pump to work like an air compressor? It would compress cold air, shoot it into the intake, with the regulation of the egr valve, but throw a T in the hose between the smog pump and egr valve with a check valve on the T side so that it don't build up too much pressure and blow the hose. All I'm hoping to do is optimize how this engine runs in every way I can. It don't run quite like I want it to just yet. Of course, I have a few other problems that need tended to, but I'm focused on this one at the moment. If that just sounds like a bunch of crazy talk with no logic, correct me, but if everything operates like I think it does, I could possibly be onto something lmao.
I'm going to be totally honest with you... none of what you said is a good idea.
You only want the EGR going into the intake when and where it's supposed to, and pumping cool air into the EGR passages won't really do anything, as there won't be enough volume to make any significant cooling. Ford speed density EFI has been around for 30+ years now, so don't go reinventing the wheel. If you want to optimize how a speed density engine runs, the most important thing is to not try to fool around with it too much. Stick to the basics, and don't go compromising efficient and reliable running to chase after a 0.25HP gain.
 
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@Rspasoje .... but, that raises combustion temperatures, causes carbon buildup over time, especially as the system's components become tired & worn.
Actually the EGR lowers the combustion temp lowing the nitrogen oxide levels. The computer adds some timing into the engine to keep things running smoothly when this process is happening.

On My 93 Bco I blocked off the egr port on the manifold and left everything attached. The intake temps are cooler and alot less carbon is getting into the intake. Another thing you can do after the EGR is blocked off is remove the coolant lines from the throttle body, that will also help lower the Air intake temps.
 

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Discussion Starter · #11 ·
@Stevo440, I think you're right. I've been having trouble finding reliable information anywhere, sifting through forums and biased opinions, rather than facts, diagrams, etc. Are there any websites or anything you would recommend for me to do some research? Id like to know all I can about how both the speed density system as well as the MAF system works. Thank you
 

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You have all the necessary parts already so just replace the Block off gasket with a regular one and return the EGR to proper operating condition. The EGR is one of the most misunderstood emissions components in existence. IT may clog once in a blue moon but it doesn't hurt anything. It also only operates under low load situations, so you'll never see a performance increase unless your EGR system had an issue. That said, if you leave it blocked off make sure to unplug the EVR or at least unplug the vacuum line so it doesn't operate. The computer will change some operating parameters when the EGR is active to account for the inert gas, if this gas is not there when it thinks it is, well that's not good. If the computer sees the EGR is not functioning it will adjust accordingly. For years my 94 had a hole in the vacuum line to the EGR, but it wasn't an issue because the truck knew it wasn't operating and just disabled it. Also I bought the truck in 2005 with 150k, it now has over 235k and I've had the EGR valve clog once in that time.
 

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I have a copy. Good book on SD systems.
 

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95 5.8L MAF XLT, Hedman Shorties/MF SS Y & Muff, E4OD, Man hubs, KYB Quads, 31x10.5x15, 304K miles
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@Stevo440, I think you're right. I've been having trouble finding reliable information anywhere, sifting through forums and biased opinions, rather than facts, diagrams, etc. Are there any websites or anything you would recommend for me to do some research? Id like to know all I can about how both the speed density system as well as the MAF system works. Thank you
Below is a short explanation of the theory/operation of the EGR System overall. There is basically no difference from SD to MAF EGR operation.


Below is a more in depth look into it.

 
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