EGR removal pro/con

[isnms]

I have a cracked egr valve. I would need to get a California egr valve. It has a temp sensor in it my ecu is looking for.

What are the pro’s and con’s of removing it.

• I think I remember reading that it helps improve fuel efficiency, lowers combustion temperatures and is environmentally friendly. I’m not opposed to that; I even installed a high flow cat instead of strait pipe.

• I think I remember reading that by removing it you remove a major source of heat and one contributor to bhg.

 

[Red Dragon]

lots of threads on this.

pro: clear up engine bay, thats pretty much it

con, higher emissions, higher combustion temps at cruise, some other stuff

search away

(My EGR is removed BTW)

 

[rakkasan]

I have a cracked egr valve. I would need to get a California egr valve. It has a temp sensor in it my ecu is looking for.

What are the pro’s and con’s of removing it.

• I think I remember reading that it helps improve fuel efficiency, lowers combustion temperatures and is environmentally friendly. I’m not opposed to that; I even installed a high flow cat instead of strait pipe.

• I think I remember reading that by removing it you remove a major source of heat and one contributor to bhg.

looks. That's about it. If you want to replace it, let me know & I'll send you one. I'm about to toss mine in the garbage.

 

[Red Dragon]

note he needs a CA one, with the ECU temp sensor. Not sure what you do about that if removed, it would throw a code for sure, which if that doesn't bother you then I guess it doesn't matter, cause you'll be failing emissions (assumig OK does this) w/o it (at least visually for sure)

 

[rakkasan]

note he needs a CA one, with the ECU temp sensor. Not sure what you do about that if removed, it would throw a code for sure, which if that doesn't bother you then I guess it doesn't matter, cause you'll be failing emissions (assumig OK does this) w/o it (at least visually for sure)

Ohhhh, didn't see that. Thanks. Thought I'd offer.....

 

[Bishop92t]

Higher or lower combustion temps from EGR removal are negligible if any. Basically all the EGR does is reroute combustion gasses from the #6 cylinder only back into the intake plenum basically to just #5 and #6 cylinders. It's hot exhaust gasses, back into the intake. The effects of removing EGR aren't noticeable on an EGT gauge, nor will it effect your gas mileage enough to notice. Removing it is cosmetic as well as clearing up an already cluttered up area. You'll find that removing the intake, starter and a few other things in that area get much easier with no EGR. If you work on your car a lot you'll enjoy that fact more then the cosmetic

You indicate you have a California model...if you chose to remove it you'll need to buy a rheostat from any electronics store, wire it up to your EGR's EGT harness, and adjust it until the CEL goes away. You could also try a 10K Ohm 1/2 watt resistor, it works for the MK4's, but for my personal experience I find a rheostat in that same range works better.

 

[isnms]

Bishop – I actually do have the resistor mod in place right now. I guess it being cracked was what was setting off the cel light, so I stuck the resistor in. It’s kept it off.
So the effects of removing it are negligible. I’ll keep that in mind.

Rakkasan – how much shipped for yours? and is it a turbo egr? I already have the resistor mod so it’s not completely necessary to get a Cali. model. I just thought I’d get that back in place.

 

[mrnickleye]

All above is basically correct. But, the exhaust gasses are routed through the intake manifold to feed 'all' the cylinders. Its purpose is to lower the peak combustion temp to lower the formation of NOx.

I leave mine on because it works properly, and by lowering the combustion temp, it helps keep the temp down in the head.

BHGs are the biggest problem the 7M motor has. And my research has shown that most of the BHGs are around the exhaust side of the #6 cylinder. And, most leak in such a way as to push combustion gasses into the coolant system.

In fact, I have not read of even one BHG that the first signs of a problem was coolant in the oil (chocolate milk). And very few that were smoking white out the tailpipe before pushing coolant over the bottle.

Plus, every 2 years here in Calif, smog test is done.

 

[johnathan1]

My BHG didn't cause coolant in the oil...at least not in noticeable amounts. Mine smoked slightly at idle, pushed coolant out, and burned coolant until it overheated...guess I got lucky.

As for emissions in Cali...my car was designated a gross pollluter, so I have to test every year...:nono:

 

[Nick M]

I have a cracked egr valve. I would need to get a California egr valve. It has a temp sensor in it my ecu is looking for.

What are the pro’s and con’s of removing it.

• I think I remember reading that it helps improve fuel efficiency, lowers combustion temperatures and is environmentally friendly. I’m not opposed to that; I even installed a high flow cat instead of strait pipe.

• I think I remember reading that by removing it you remove a major source of heat and one contributor to bhg.

You are incorrect on both accounts, sort of. It does lower combustion temps. It does this by reintroducing spent inert gasses into the combustion process, displacing some oxygen. This does not help efficency, it hurts it. By lowering combustion temps you lower NOx, a compound that forms on its own in the upper atmosphere, but increase HC and CO compounds. The catalytic converter clean up all three compounds though.

Too much EGR, or having it stick open can cause a manifold backfire. It isn't common. Air and fuel are in the intake, and the heat is reintroduced and you have the components of combustion. When it is in the combustion chamber going through the 4 cycles, it doesnt do anything except lower combustion temps.

And since you noted the lower combustion temps, how would that make more heat and BHG? It doesn't obviously.

 

[isnms]

Thanks for all the information. I will be replacing the valve/keeping it in.

So I am looking for a California type but I checked the tsrm and it shows two different part numbers for <89 and 89+. So it seems I need an 89+ type also.

 

[turbogate]

A question that as never been really answered in the many EGR threads:
Is there another reason beside emission control that the Japanese did NOT put the EGR systems in the JDM 7MGTE ? I even wonder if the europeen version have it.

Later

 

[Bishop92t]

All above is basically correct. But, the exhaust gasses are routed through the intake manifold to feed 'all' the cylinders. Its purpose is to lower the peak combustion temp to lower the formation of NOx.

Study the intake plenum design, you'll see that EGR is effectively only fed to cylinder 5 and 6. There may be a little that reachs 3 and 4, but I doubt any get to 1 and 2.

If you live in a state with emissions testings you're going to want to leave it on. It doesn't effect performance or reliability one way or another. Just look at the Jap spec 7m's, they don't have EGR and they are no better or worse for BHG's then we are. As for Toyota's reason, EGR systems cost money, why waste it if your local laws don't require it?

 

[jetjock]

Hmmm....ECU programing in non-EGR cars is different. Those of you who pull the EGR off seem to forget the ECU was programmed for it. It still does things thinking EGR is there. These actions can easily be observed using a labscope and a gas analyzer.

As I've pointed out before, the use of EGR was originally used for detonation surppresion. It's ability to reduce NOx was discovered accidentally. Fwiw here's a quote lifted directly from the Toyota TCCS Technical Service publication:

EGR impact on the Engine Control System:

1) The ECU considers the EGR system an intergral part of the engine control system and is capable of neutralizing the negative performance aspects of EGR flow by programming additional spark advance and decreased fuel injection during periods of high EGR flow. By intergrating fuel and spark control engine performance and fuel economy are actually enhanced when the EGR system is functioning as designed.

2) Loss of EGR flow will cause detonation and emissions failures. Because EGR tends to reduce the volitility of the air/fuel charge loss of EGR flow will typically result in detonation. If EFR is commanded and doesn't flow (restricted passage, nonfunctional valve, etc) severe detonation will occur.

 

[jdub]

JJ - would use of a JDM ECU negate this if your EGR was removed?

 

[jetjock]

I don't know for sure but I assume so. Everything I've learned shows TCCS coding varies depending on where the car was intended to be sold. emissions, etc, and if the car didn't have EGR it seems logical the correction routines wouldn't be there.

The point is under load the ECU advances spark and decreases fuel to compensate for commanded EGR flow. Advances spark and decreases fuel. Think about that. Also keep in mind the book considers an engine making only stock power.

Even with a domestic ECU you can tune around this but the point is the ECU will still be doing as it was programmed no matter what you do with tuning. When messing around with things that always has to be kept in mind.

 

[cnewingham]

I personally removed mine due to the fact that all the intake pleniums I have removed that contained the egr system was caked with carbon and everything else that is included by recirculating the exhaust gases. Think of what it does the valves, seats, and seals. A cleaner running enginer is a better running engine in the long run. I do understand the effects it MAY cause but it doesnt have as much as an ill effect as all that build up in your intake.

 

[turbogate]

If i'm not mistaking, EGR only functions during cruising anyways, not WOT. So what ever the TCCS does based on EGR would be during normal driving/cruising anyways. Thus I dont think theres a risk of detonation etc on WOT. Detonating during cruising would probably be a first:icon_bigg

 

[Joel W.]

My (secret book of info) says EGR is shut off when the engine is not up to temp and or when above 4000-4500 rpm... Not sure if wide open thottle has anything to do with it?

But then again, it also says it shuts the EGR off when the air intake volume per engine revolution is above a predetermined level or when the fuel cut function is on. :dunno:

 

[jetjock]

If i'm not mistaking, EGR only functions during cruising anyways, not WOT. So what ever the TCCS does based on EGR would be during normal driving/cruising anyways. Thus I dont think theres a risk of detonation etc on WOT. Detonating during cruising would probably be a first:icon_bigg

You gotta be kidding. There are many causes of detonation and in fact the vast majority of det events occur at other then WOT. You think your engine has knock sensors just for WOT use? How do you think the 7M makes the power it does on 188 cubic inches? Why does the owner's manual state 87 octane is all that's required?

It's because the ESA system is aggressive, it pushes the spark envelope all the time. The knock sensors aren't just passively sitting there waiting for one of the many causes of detonation to occur. In short the ECU depends on EGR for det suppression more than you think.

Add in high charge temps and the other things common to sloppily modded turbo engines and you'd better know what you're doing at other than WOT if you're going to defeat a system the ecu is not only programmed to work with but depends on. It's your car though....you can do as you like.