7MGTE egr or no egr

[IndigoMKII]

I'm currently building a 7mgte that was a brand new long block so my question is.. Egr or no egr? I ask this question because the previous owners have either removed/lost the egr pieces while they stripped the old block/head before purchasing the new one. So in order for me to put egr back on this new engine, I'll need to purchase the cooler plate, egr vacuum modulator, vacuum manifold that goes under the intake, bvsv and the vsv for the egr system. I'm trying to weigh the advantages/disadvantages of using it and not using it, because of the price it'll cost to purchase all of it. If absolutely needed I can/will wait until I have all the egr pieces. I'm mainly looking for opinions on the matter.

 

[CyFi6]

http://www.google.com/search?hl=en&...upl=251107l253980l0l7l5l0l0l0l0l298l802l2-3l3
All the opinions you will ever need! I don't normally tell people to search but there's a crap ton of info there already.

 

[kotu100]

unless running a JDM ecu you should put the egr back on for sure.

 

[Another MkIII]

EGR for sure, USDM ECUs are tuned to run EGR, running no EGR with the USDM ECU can cause knock and damage to the motor. If you want to stay without EGR, you will need to either get a JDM ECU, or a means of tuning it to run without EGR. Not sure if any piggybacks can do that, but a standalone will work. Putting EGR back on is probably the cheapest option. I got an EGR valve and modulator for $35 from a member here. There is always somebody parting out on here, so finding the whole system shouldn't cost you more than about $100, which is less than you will spend on anything that allows you to run an alternative tune.

Also, I believe the BVSV is part of the EVAP system, you can do without it, especially if you don't drive the car in colder weather. I have a temp sensor off of a Ford in its place for my fan controller, lol.
-AM3

 

[ask92]

Agreed, the ecu wont like not having the egr.

 

[hvyman]

Theres no gains from removing it either.

 

[tomsupra8683]

There is a gain to not running it.:your intakemanifold and valves dont get clogged with garbage from the exhaust.Ive had no problem running no egr on my 7mgte,but idk if my ecu is a jdm one or not it may be.

 

[Poodles]

Complaining about soot in your intake is like complaining about your air filter being dirty. It's called maintenance..

 

[hvyman]

Takes forever for it to build up to complain about anything anyways. And if you wot everywhere you wont even get any cause the valve will never been open.

 

[suprarx7nut]

I run a JDM ECU and no EGR. Not really by choice, but because the previous owner of my engine had it like that and I didn't want to bother getting all the pieces again.

If you have a USDM ECU you're going to have to spend some money to get it right again. Either a JDM ECU (easiest solution, IMO) or all the EGR components.

Running no EGR and a USDM ECU is like 7M suicide... :nono:

 

[Tony]

I'm rebuilding my engine too and I have the whole system you can buy if you want. Since its worth at least a hundred, I'll sell it for $75. Let me know

 

[suprajztwenty]

here in tx i barely passed smog with no egr...but that was also because they didnt actually roll my car, they just revved it up and fooled the machine, somehow i passed with a mini high flow cat and full 3", stock everything otherwise.

i think with the new motor ill go ahead and buy the egr pieces and if soot/intake temps are your concern, just because its on, doesnt mean it cant be disabled and set up for smog tests later.

i dont understand the concept that a usdm ecm wont run properly without egr. especially since it wont throw a fault code with it blocked off. i could maybe understand a vacuum solenoid valve causing a symptom but as far as what the ecm sees, i dont get how it would know its flowing or not. o2 sensor changes? as far as damage goes, please explain further...humor me

 

[hvyman]

Theres unburnt fuels in the exhaust. Ecu has that programmed into the afrs.

Car will run fine just leaner. Better to keep it on or tune around it.

 

[Poodles]

Response to when EGR is active is advanced timing and less fuel. Disable EGR and you're asking for detonation.

 

[Tony]

So your saying when the EGR is active, the ecu advances the timing to make up for the loss of fuel. So when its not active or blocked off, there is more fuel. So my question is, how can disabling it cause detonation?

 

[Poodles]

It doesn't know you disabled it.

 

[Tony]

So if it doesn't know you disabled it, when it thinks it is open, it will dump more fuel to compensate. I thought less fuel more oxygen caused detonation not more fuel.

 

[hvyman]

There is no command for more fuel its less fuel and more timing. When there is no egr your missing the fuel in the exhaust gasses that the ecu thinks is there and you run lean causing detonation.

It doesnt know its not there so it still assumes there is fuel coming from the egr.

 

[Van]

So your saying when the EGR is active, the ecu advances the timing to make up for the loss of fuel. So when its not active or blocked off, there is more fuel. So my question is, how can disabling it cause detonation?

The following may be instructive: "... 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.

'... 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.'" Nick M

"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. " JetJock

Our Supras w/ stock TCCS need EGR... Van

 

[CyFi6]

I was always under the impression that the ECU would monitor in intake air volume and use that to verify the EGR was in fact operating. It just seems odd that they would have no way to know if it was actually working, when having it not working could cause engine damage.