EGR Removal Pro's and Cons
02-23-2007, 10:59 AM
#1
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Thread Starter
EGR Removal Pro's and Cons
There seems to be many threads on how to take the EGR system off, but I'd like to know what are some pro's and cons, beside the obvious, (more emissions). I am running a 3.0 and where I live we dont have smog testing! so Im not worried about that factor.
Im guessing it would improve gas mileage aswell as power by not trying to reburn, burn exhaust gases. Also this would lead me to believe that there would be a smoother running engine, because the motor is now running on "pure" air. What are some of the cons? I couldn't think of any cons that would effect the motor running itself, only enviroment issues. Does the computer shoot codes if it doesnt sense EGR?
Im guessing it would improve gas mileage aswell as power by not trying to reburn, burn exhaust gases. Also this would lead me to believe that there would be a smoother running engine, because the motor is now running on "pure" air. What are some of the cons? I couldn't think of any cons that would effect the motor running itself, only enviroment issues. Does the computer shoot codes if it doesnt sense EGR?
02-23-2007, 11:12 AM
#2
I may have to start considering my self a foremost expert on the subject, as I read about it in the daily threads here.That obvious more emmisions thought, though not entirely false, can become less obvious as to it's truth in some cases. Some people have experienced a poorer running engine, pinging and/or no performance gains, which makes the disturbance of a functioning system less than desirable. My computer doesn't throw a code with mine by-passed, but I ain't sure why, so I can't tell ya there.
02-23-2007, 11:19 AM
#3
Registered User
Thread Starter
I am not necessarily looking for more power, but a more economical engine. I was wondering about how the engine would run, seeing that the motor was designed to have this extra "bad" air coming in, and is probably metered somehow. Blocking this off would take away that extra air, and now would the motor run rich? The other reason I was hoping to get rid of the EGR was to help clean up the clutter in the engine bay, just one less thing to go through with troubleshooting if something was to fail.
02-23-2007, 11:25 AM
#4
I'll go as far as to say no, it would increase the vauum in the intake(plenum), causing more air to be drawn in through the throttle body, compensating for any rich mixture. I think your fully justified in experimenting with your vehicle, and recommend so personally.
Last edited by MudHippy; 02-23-2007 at 11:26 AM.
02-23-2007, 12:57 PM
#5
Registered User
To accurately answer this question, you have to know how the mapping routine in the ECM works. I don't have that exact information.
The ECM fuels the engine based on a fuel injection map and also input from a number of sensors, such as incoming air temperature sensor, barometric pressure sensor (elevation), coolant temperature sensor, O2 sensor, etc.
A totally reactive FI system will have a very "flexible" map. Fuel delivery would be based less on a rigid map and more on sensor input. These sytems are more expensive to create, and are not very "maintenance-free" because anomalous input from any sensor can whack the ECM.
Production vehicles usually have a less reactive system. The map is more rigid. It fuels the engine primarily according to rpm & throttle position, with less weight given to various sensor input. That way, if any sensor fails, the engine can either still operate acceptably, or default to a totally rpm-and-throttle based fueling algorithm until the owner repairs the failed sensor(s). In other words, consumers don't get stranded very often. The rigid maps are fairly inefficient.
Regarding the EGR, it is likely that the ECM map assumes that the EGR is functioning properly, and fuels the vehicle slightly leaner during conditions in which the EGR would be open, OR, if the EGR fails, the ECM will recognioze the failure, and then default to a rigid (inefficient) fueling algorithm.
What this means is that if you block off the EGR and then:
- install a resisitor or some other electric whizbang to fool the ECM into thinking that the EGR is present and functional, then the ECM will fuel accordingly, and you will be inefficient (lean), OR...
- don't fool the ECM with a resistor, then the ECM will know the EGR is absent, and will default to the rigid map, and you will be inefficient.
Alternately, it's possible that these early toyota ECM's are highly advanced and that if you take the EGR off, the ECM will compensate in a friendly manner, and operate your engine perfectly in it's absence.
That last scenario is highly uinlikely.
Only a tech who knows exactly how EGR impacts the fueling algorithm can answer your question.
But I will wager $20 that the ECM code has two EGR scenarios:
1 - the EGR is working properly, and the ECM is fueling according
2 - the EGR is not working properly, and the ECM has defaulted to a rigid map
In other words, I feel quite certain that the ECM will not use the O2 sensor to properly fuel the engine once it has recognized the absence of the EGR.
A note on the EGR:
It's only open during off-load condtions.
The ECM will only open the EGR and then simultaneously alter fueling to the EGR-open algorithm, when it recognizes a pre-defined off-load condition.
The EGR is closed, and the engine is breathing only fresh air during load conditions.
The purpose of the EGR is to inject exhaust gases into the intake during offload operating conditions to reduce compbustion temperature.
That is it's sole purpose.
Reduced combustion temperature is good.
Since the EGR is never open during "on load" conditions, it doesn't affect the "power output" of the engine. You won't get more power by removing it.
Since EGR is only open during off-load conditions, like floating downhill on cruise control, and since the ECM provides less fuel to create the proper air/fuel ratio at any time that the EGR is open, you will actually decrease your fuel economy if you remove it.
If you block it off and fool the ECM, the ECM will supply less fuel when it commands EGR to open. This means you will be running lean, which is bad for your engine and REDUCES fuel economy. Lean does not save gas. Rather, lean reduces efficiency.
If you block it off and don't fool the ECM, the ECM will just default to the inefficient "trouble" map, and you will lose fuel economy, and likely engine performance.
Whew!
I'm never going to explain that again.
The ECM fuels the engine based on a fuel injection map and also input from a number of sensors, such as incoming air temperature sensor, barometric pressure sensor (elevation), coolant temperature sensor, O2 sensor, etc.
A totally reactive FI system will have a very "flexible" map. Fuel delivery would be based less on a rigid map and more on sensor input. These sytems are more expensive to create, and are not very "maintenance-free" because anomalous input from any sensor can whack the ECM.
Production vehicles usually have a less reactive system. The map is more rigid. It fuels the engine primarily according to rpm & throttle position, with less weight given to various sensor input. That way, if any sensor fails, the engine can either still operate acceptably, or default to a totally rpm-and-throttle based fueling algorithm until the owner repairs the failed sensor(s). In other words, consumers don't get stranded very often. The rigid maps are fairly inefficient.
Regarding the EGR, it is likely that the ECM map assumes that the EGR is functioning properly, and fuels the vehicle slightly leaner during conditions in which the EGR would be open, OR, if the EGR fails, the ECM will recognioze the failure, and then default to a rigid (inefficient) fueling algorithm.
What this means is that if you block off the EGR and then:
- install a resisitor or some other electric whizbang to fool the ECM into thinking that the EGR is present and functional, then the ECM will fuel accordingly, and you will be inefficient (lean), OR...
- don't fool the ECM with a resistor, then the ECM will know the EGR is absent, and will default to the rigid map, and you will be inefficient.
Alternately, it's possible that these early toyota ECM's are highly advanced and that if you take the EGR off, the ECM will compensate in a friendly manner, and operate your engine perfectly in it's absence.
That last scenario is highly uinlikely.
Only a tech who knows exactly how EGR impacts the fueling algorithm can answer your question.
But I will wager $20 that the ECM code has two EGR scenarios:
1 - the EGR is working properly, and the ECM is fueling according
2 - the EGR is not working properly, and the ECM has defaulted to a rigid map
In other words, I feel quite certain that the ECM will not use the O2 sensor to properly fuel the engine once it has recognized the absence of the EGR.
A note on the EGR:
It's only open during off-load condtions.
The ECM will only open the EGR and then simultaneously alter fueling to the EGR-open algorithm, when it recognizes a pre-defined off-load condition.
The EGR is closed, and the engine is breathing only fresh air during load conditions.
The purpose of the EGR is to inject exhaust gases into the intake during offload operating conditions to reduce compbustion temperature.
That is it's sole purpose.
Reduced combustion temperature is good.
Since the EGR is never open during "on load" conditions, it doesn't affect the "power output" of the engine. You won't get more power by removing it.
Since EGR is only open during off-load conditions, like floating downhill on cruise control, and since the ECM provides less fuel to create the proper air/fuel ratio at any time that the EGR is open, you will actually decrease your fuel economy if you remove it.
If you block it off and fool the ECM, the ECM will supply less fuel when it commands EGR to open. This means you will be running lean, which is bad for your engine and REDUCES fuel economy. Lean does not save gas. Rather, lean reduces efficiency.
If you block it off and don't fool the ECM, the ECM will just default to the inefficient "trouble" map, and you will lose fuel economy, and likely engine performance.
Whew!
I'm never going to explain that again.
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02-23-2007, 01:07 PM
#6
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Thread Starter
wow, awesome response. What you said makes alot of sense, and that was part of my initial question that if I was to remove it, would the computer go into "dumb" mode and throw codes. I was unaware however that the EGR only flows on off-load, not under load. Then the EGR would not restict any preformance what so ever. Anyone else have any comments? What have others seen with the removal of their EGR setup?
02-23-2007, 01:13 PM
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That's assuming it's working correctly. It is not uncommon for the EGR valve to get stuck open. I removed mine a couple weeks ago and I've been very happy with the results. More power, smoother operation.
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02-23-2007, 01:32 PM
#8
Don't worry guys, see what he says to this. The adding of residual heat, from the EGR valve, into the air/fuel ratio, at the point where the valve enters the flow, does not make for efficiency or power.Nor is it affectable by the ECM. This as well as the other harmfull effects of the pre-fouled gasses, on several levels, is not productive at all. EGR's are equivelant to SATAN, at least to me. Bad stuff, I gotta search a little, but I heard they don't put them on vehicles anymore.
Last edited by MudHippy; 02-23-2007 at 01:38 PM.
02-23-2007, 02:05 PM
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To accurately answer this question, you have to know how the mapping routine in the ECM works. I don't have that exact information.
The ECM fuels the engine based on a fuel injection map and also input from a number of sensors, such as incoming air temperature sensor, barometric pressure sensor (elevation), coolant temperature sensor, O2 sensor, etc.
A totally reactive FI system will have a very "flexible" map. Fuel delivery would be based less on a rigid map and more on sensor input. These sytems are more expensive to create, and are not very "maintenance-free" because anomalous input from any sensor can whack the ECM.
Production vehicles usually have a less reactive system. The map is more rigid. It fuels the engine primarily according to rpm & throttle position, with less weight given to various sensor input. That way, if any sensor fails, the engine can either still operate acceptably, or default to a totally rpm-and-throttle based fueling algorithm until the owner repairs the failed sensor(s). In other words, consumers don't get stranded very often. The rigid maps are fairly inefficient.
Regarding the EGR, it is likely that the ECM map assumes that the EGR is functioning properly, and fuels the vehicle slightly leaner during conditions in which the EGR would be open, OR, if the EGR fails, the ECM will recognioze the failure, and then default to a rigid (inefficient) fueling algorithm.
What this means is that if you block off the EGR and then:
- install a resisitor or some other electric whizbang to fool the ECM into thinking that the EGR is present and functional, then the ECM will fuel accordingly, and you will be inefficient (lean), OR...
- don't fool the ECM with a resistor, then the ECM will know the EGR is absent, and will default to the rigid map, and you will be inefficient.
Alternately, it's possible that these early toyota ECM's are highly advanced and that if you take the EGR off, the ECM will compensate in a friendly manner, and operate your engine perfectly in it's absence.
That last scenario is highly uinlikely.
Only a tech who knows exactly how EGR impacts the fueling algorithm can answer your question.
But I will wager $20 that the ECM code has two EGR scenarios:
1 - the EGR is working properly, and the ECM is fueling according
2 - the EGR is not working properly, and the ECM has defaulted to a rigid map
In other words, I feel quite certain that the ECM will not use the O2 sensor to properly fuel the engine once it has recognized the absence of the EGR.
A note on the EGR:
It's only open during off-load condtions.
The ECM will only open the EGR and then simultaneously alter fueling to the EGR-open algorithm, when it recognizes a pre-defined off-load condition.
The EGR is closed, and the engine is breathing only fresh air during load conditions.
The purpose of the EGR is to inject exhaust gases into the intake during offload operating conditions to reduce compbustion temperature.
That is it's sole purpose.
Reduced combustion temperature is good.
Since the EGR is never open during "on load" conditions, it doesn't affect the "power output" of the engine. You won't get more power by removing it.
Since EGR is only open during off-load conditions, like floating downhill on cruise control, and since the ECM provides less fuel to create the proper air/fuel ratio at any time that the EGR is open, you will actually decrease your fuel economy if you remove it.
If you block it off and fool the ECM, the ECM will supply less fuel when it commands EGR to open. This means you will be running lean, which is bad for your engine and REDUCES fuel economy. Lean does not save gas. Rather, lean reduces efficiency.
If you block it off and don't fool the ECM, the ECM will just default to the inefficient "trouble" map, and you will lose fuel economy, and likely engine performance.
Whew!
I'm never going to explain that again.
The ECM fuels the engine based on a fuel injection map and also input from a number of sensors, such as incoming air temperature sensor, barometric pressure sensor (elevation), coolant temperature sensor, O2 sensor, etc.
A totally reactive FI system will have a very "flexible" map. Fuel delivery would be based less on a rigid map and more on sensor input. These sytems are more expensive to create, and are not very "maintenance-free" because anomalous input from any sensor can whack the ECM.
Production vehicles usually have a less reactive system. The map is more rigid. It fuels the engine primarily according to rpm & throttle position, with less weight given to various sensor input. That way, if any sensor fails, the engine can either still operate acceptably, or default to a totally rpm-and-throttle based fueling algorithm until the owner repairs the failed sensor(s). In other words, consumers don't get stranded very often. The rigid maps are fairly inefficient.
Regarding the EGR, it is likely that the ECM map assumes that the EGR is functioning properly, and fuels the vehicle slightly leaner during conditions in which the EGR would be open, OR, if the EGR fails, the ECM will recognioze the failure, and then default to a rigid (inefficient) fueling algorithm.
What this means is that if you block off the EGR and then:
- install a resisitor or some other electric whizbang to fool the ECM into thinking that the EGR is present and functional, then the ECM will fuel accordingly, and you will be inefficient (lean), OR...
- don't fool the ECM with a resistor, then the ECM will know the EGR is absent, and will default to the rigid map, and you will be inefficient.
Alternately, it's possible that these early toyota ECM's are highly advanced and that if you take the EGR off, the ECM will compensate in a friendly manner, and operate your engine perfectly in it's absence.
That last scenario is highly uinlikely.
Only a tech who knows exactly how EGR impacts the fueling algorithm can answer your question.
But I will wager $20 that the ECM code has two EGR scenarios:
1 - the EGR is working properly, and the ECM is fueling according
2 - the EGR is not working properly, and the ECM has defaulted to a rigid map
In other words, I feel quite certain that the ECM will not use the O2 sensor to properly fuel the engine once it has recognized the absence of the EGR.
A note on the EGR:
It's only open during off-load condtions.
The ECM will only open the EGR and then simultaneously alter fueling to the EGR-open algorithm, when it recognizes a pre-defined off-load condition.
The EGR is closed, and the engine is breathing only fresh air during load conditions.
The purpose of the EGR is to inject exhaust gases into the intake during offload operating conditions to reduce compbustion temperature.
That is it's sole purpose.
Reduced combustion temperature is good.
Since the EGR is never open during "on load" conditions, it doesn't affect the "power output" of the engine. You won't get more power by removing it.
Since EGR is only open during off-load conditions, like floating downhill on cruise control, and since the ECM provides less fuel to create the proper air/fuel ratio at any time that the EGR is open, you will actually decrease your fuel economy if you remove it.
If you block it off and fool the ECM, the ECM will supply less fuel when it commands EGR to open. This means you will be running lean, which is bad for your engine and REDUCES fuel economy. Lean does not save gas. Rather, lean reduces efficiency.
If you block it off and don't fool the ECM, the ECM will just default to the inefficient "trouble" map, and you will lose fuel economy, and likely engine performance.
Whew!
I'm never going to explain that again.
unfortunately, you're not totally correct. Placing a resistor WILL fool the ECM. The temp sender uses resistance to signal the ECM the condition of the EGR. The ECM won't automatically "know its fooled" and revert to a lean or rich condition, it totally depends what value resistor you put in. The proper output resistances under various driving conditions are listed in the manuals for testing purposes, you can place the correct one that corresponds to a steady cruise state and have the exact same efficiency as with the EGR properly installed.
In most cases, people disable the EGR when it is working improperly, not to gain power, but to restore power, therefore there really isn't much to lose.
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Andrew Parker (04-10-2021)
02-23-2007, 02:30 PM
#11
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... Placing a resistor WILL fool the ECM. The temp sender uses resistance to signal the ECM the condition of the EGR. The ECM won't automatically "know its fooled" and revert to a lean or rich condition, it totally depends what value resistor you put in. The proper output resistances under various driving conditions are listed in the manuals for testing purposes, you can place the correct one that corresponds to a steady cruise state and have the exact same efficiency as with the EGR properly installed.
If you use the resistor that corresponds to steady cruise, then the ECM will assume the EGR is open (allowing exhaust gas into intake), and will reduce fuel accordingly. But since you have no EGR, and therefore no exhaust gas, the only supply of air will be fresh air, and the engine will be lean. When the EGR recognizes this lean condition via O2 sensor input, it will not automatically enrichen the fuel mix. If the measured O2 reading is "lean but not dangerously lean", the ECM will do nothing, and you will just be driving around slightly lean all the time, with less power and poorer fuel economy. On the other hand, if the mix is so lean that it exceeds the programmed threshhold, you'll get a code, and the engine will likely run in "trouble mode" until you fix it.
Also, assuming you use the "steady cruise" resistor, when you mash the gas, the ECM will think the EGR is still open becaause that's what resistance it is seeing, and it will either throw a code, or will simply fuel for "open EGR", which is less power and less efficiency. In other words, you've bypassed a system that is supposed to open the EGR only when operating under light loads, and converted it to a system that has the EGR open all the time, even during heavy loads.
The same sort of argument applies to any other resistor you want to install. Just follow the logic through the routine. A single resistor will always land you in trouble in some operating condition.
If you want to remove an EGR and run properly, the process is simple: either crack the ECM and reprogram it to operate without an EGR (remove all the EGR subroutines from the program), or buy a chip or other interface that accomplishes the same thing by getting betwen the sensors and the ECM. An example is a Power Commander module from Dynojet. I doubt they make a PC for a 4runner
, but I've used several on bikes.
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Andrew Parker (04-10-2021)
02-23-2007, 02:40 PM
#12
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Let me clarify the PC comment.
I've used several PC's on bikes to "re-map" fuel injection after installing pipes and cams. Not to delete EGR's. Bikes don't have EGR's.
Bikes do have bomb-proof ECM's that cost $600 or more, and they fry themselves if you try to crack them.
So Dynojet created a lucrative market by making FI mapping software that can be used to tune FI systems on the fly while on a dyno. You're not actualling reprogramming the ECM. Your programming the Power Commander module, which then accomplishes what you want by intercepting signals from temperature and baro and throttle and rpm sensors, and actually fudging those signals before sending them on to the ECM, to cause the ecm to increase or decrease fueling.
Crazy, but common, and very effective. A PC has a male and female ECM plug that exactly mirrors the plug on the vehicle you bought it for. You unplug the cable from the ECM, plug it into the PC, and then plug the PC into the ECM.
I've used several PC's on bikes to "re-map" fuel injection after installing pipes and cams. Not to delete EGR's. Bikes don't have EGR's.
Bikes do have bomb-proof ECM's that cost $600 or more, and they fry themselves if you try to crack them.
So Dynojet created a lucrative market by making FI mapping software that can be used to tune FI systems on the fly while on a dyno. You're not actualling reprogramming the ECM. Your programming the Power Commander module, which then accomplishes what you want by intercepting signals from temperature and baro and throttle and rpm sensors, and actually fudging those signals before sending them on to the ECM, to cause the ecm to increase or decrease fueling.
Crazy, but common, and very effective. A PC has a male and female ECM plug that exactly mirrors the plug on the vehicle you bought it for. You unplug the cable from the ECM, plug it into the PC, and then plug the PC into the ECM.
02-23-2007, 02:51 PM
#13
Or save your money, and just by-pass the valve. You might get some "scary" inefficient fuel (rigid mapping blah, blah, blah, sounds good on paper) yada yada yada, but not likely. Because of the opposing forces involved with the replacing of dirty, hot gasses with cool, clean burning air, efficiency ensues. Man, that guy finally got the point, NOT LIKELY! I bet he's got a pricey gadget, that isn't worth its weight in monkey feces, he'll sell me, though. lmfao
Last edited by MudHippy; 02-23-2007 at 05:18 PM.
02-24-2007, 04:12 AM
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the only thing your going to gain from doing this, is knowing that your contributing to making the air we breathe worse. with out the egr you will produce excessive nox(oxides of nitrogen). its the reason egr was in corporated in vehicles. nox is probably the worse gas that your vehicle releases. egr will only work when you are cruising at higher speeds most likely on the highway. it reburns those gases to get rid of the nox.
hey while your at it, take your cat out. then open your hood and disconnect your ect(engine coolant temp sensor) so that your engine runs rich.
that way you can put out even worse emissions with still no gain besides are horribly running engine.
im sure the big time tread lightly guys like hearing this
hey while your at it, take your cat out. then open your hood and disconnect your ect(engine coolant temp sensor) so that your engine runs rich.
that way you can put out even worse emissions with still no gain besides are horribly running engine.
im sure the big time tread lightly guys like hearing this
02-24-2007, 05:32 AM
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I don't think the argument in favor of removal is for performance gains, but rather "thriftiness." For some, it might be easier to remove a broken EGR system rather than buy a new valve ($135+). Plus, one could effectively rule out the EGR system in future troubleshooting.
02-24-2007, 05:41 AM
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it is better than spending money on a new setup, but its not going to make diag. easier. ecm knows when egr should be active, if it dosent see it im sure it creates more problems. it being obd1 you might just get lucky, but i doubt it helps the motor. just the $.02 from a young tech. im not a master yet.
02-24-2007, 05:49 AM
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it is better than spending money on a new setup, but its not going to make diag. easier. ecm knows when egr should be active, if it dosent see it im sure it creates more problems. it being obd1 you might just get lucky, but i doubt it helps the motor. just the $.02 from a young tech. im not a master yet.
02-24-2007, 06:37 AM
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Yeah usually ill agree with that statement BUT if you look at newer engines now they don't have an egr. the egr was a quick fix to get the engines emissions down for the states. My engine hasn't thrown a code since i bypassed it my idle and acceleration are ten times smoother. the power band from 2-3K is more powerful. Now i don't know about the emissions part now but my exhaust is significantly louder the flowmaster is finally awakened. i have a 92' 3.0 and here in NC i dont' have to get smogged anymore so if i can take off things that were preventing my engine to perform and run better then im going to. My MPG went up 1 mpg from 15 to 16 since i removed it so that by itself is worth it.
