Junkers88

On the 86 I blocked it off and have no issues, even posts better numbers at the emissions place.

On the 89 there is a little sensor in the top of the EGR tube attached to the intake plenum. I keep getting the dang EGR code and since I think it may be just about the dumbest thing ever created I wondering if I can block it off and have the code go away.

Thoughts? Tomorrow I'm replacing the O2 sensor to eliminate that code and doing a full tune up since my 14mpg in town just drives me nuts. I want to block off the EGR at the same time.



Thanks for your help folks.

Jay351

If the EGR has a temp sensor, use a 10k resister to jump the connectors to fool the sensor into thinking everything is a-ok

Junkers88

Ok I have no idea how to wire in a resistor. Is it something I can pick up at NAPA and just put in with butt connectors?

Jay351

Im pretty sure you just stuff it into the female connectors, essentially jumping the connector. It just needs to read the resistance

Search EGR removal/blockoff. I remember reading up on how to do this, but my truck doesnt have a temp sensor..

toyota4x4907

Like Jay said, its the EGR temp sensor. It was on 22r-ec models I do believe.

question--do they not have "visual" inspections of the emissions stuff in NM, Junkers?

Junkers88

The "visual" is usually "Hmmmm clean motor, do you still have the cat?"



I'm thinking I can block it off but leave it in there. That way it's still hooked up but out of the system. I just think it's stupid to run exhaust gasses back through the intake. My motors don't run so rich that they leave unburnt fuel. That and with the PAIR valve pumping clean air into the exhaust the emissions numbers are already great.

toyota4x4907

lol. okay. Cuz like up here, and I know other places, they visually inspect the emissions junk, make sure everything is still connected and whatnot.

I've heard/read that the engine might run a little hotter without the EGR doing it's job. Not quite sure how valid that is, but might be something to look in to.

I <3 teh PAIR system

sb5walker

The combustion temps ARE hotter without the EGR - that's what it does: lowers combustion temps to reduce the formation of nitrous oxide. It also improves gas mileage slightly and reduces pinging. Higher combustion temps put additional stress on the head gaskets since the head and block are dissimilar metals and have different expansion rates - the more heat, the more they move relative to each other. The exhaust valves don't like the hotter temps much, either.

ffryno13

hi-jack sorry quick question which ports do you jump on the OBD?

Junkers88

T and E1



Not that I'm doubting you but I have a hard time understanding how introducing hot exhaust gas into the combustion chamber is going to lower the temperature.

I also don't understand how introducing hot air into the cylinder is going to help improve fuel milage. I mean a bunch of us are modding the intake to get cooler air from outside the engine compartment and the dang EGR is just pumping hot air back in.

This may be one of those things that I'll never fully understand.

Justinlhc

I used a 1kohm resistor and it hasn't thrown a code at me yet. I just plugged an end into each connector that went to the sensor and taped over it to make sure it stayed in place.

Junkers88

Where did you get the resistor? Is that something that I can find at a radio Shack?

BigBluePile

iTrader: (3)

Yup, Radio Shack should have all the resistors you need! I picked up some there when I had to make an aux input cable for my wifes stereo in her car.

sb5walker

It is counter-intuitive. By the time the egr gas has been deposited in the plenum, it has passed through a good length of iron pipe, so it has cooled quite a bit. But you're right - it's still hotter than the intake air. The reason it cools combustion temps is that it's an inert gas - and the presence of inert gas (that doesn't combust) in the midst of combusting gasses has a cooling effect.

As mentioned, the main reason for introducting egr is to reduce the creation of oxides of nitrogen - one of the most toxic components in smog. Nox will only form at very high temps. By reducing the combustion temp, more of the oxygen will react with the carbon, and less of it will react with the nitrogen present in the air.

This is one of the reasons egr gives a bit better mileage - you lose less oxygen to the nitrogen, a reaction which gives no power, and so there's more oxygen to combine with carbon, the reaction that gives the power.

The other factor that gives better mileage is due to the slowing of the combustion. The egr helps the combustion to be an even burning, instead of a sudden explosion (ping). The sudden explosion will cause maximum pressure to be developed too soon - before the piston is at the perfect place for peak pressure (around 15-17 degrees after TDC). So by helping the peak combustion to occur at the right time and place, the egr helps the motor develop more power.

Another factor is that when the computer detects pinging, it retards the timing, with further reduces power.

It is true that the introduction of an inert gas into the intake effectively reduces the displacement of the motor, and that does reduce the available power. For this reason, the egr does not activate when the tps detects full throttle, nor does it function at idle. It only operates at cruise, or at less than full throttle acceleration, giving the benefits of fuel efficiency, less stress on the motor, and reduced formation of Nox when max power is not needed.

Lumpy

If I didn't know any better I think I just learned a bit today. Very interesting...

Justinlhc

Yup, they have TONS of them. It was like $0.99 for 2 of them. I guess now I have a spare.

Jay351

I blocked mine off last year, and I noticed almost no change in performance or anything. I might try it again before summer. I wish I could see some numbers of the actual temp increase the lack of EGR causes...

Justinlhc

I can't say I noticed a difference, but I'm always messing with something so it's hard to say. I just feel better knowing I don't have hot exhaust being directed into my intake manifold, regardless of the theory behind the system.

sb5walker

I'd be interested to see that too. It would be easy to do using an IR thermometer on the exhaust manifold. Of course make sure the EGR is working right in the first place. Hold rpms at 2500 with EGR active until the temp stabilizes, then pull and plug the egr vacuum hose and hold rpm at 2500 again until temp stabilizes. Temps should be higher without the egr.

You should also be able to see differences in nox emissions at the tailpipe and signs of hotter combustion on the plugs.

I think it would be more risky to run a 3vze without egr than the 22re. Burning high octane would lessen the risk, as would headers.

I don't have an IR thermometer, otherwise I'd do the test on my veezy. I see the well-rated Mastercool MSC52224A is only $45 shipped at amazon...

Jay351

Yes, heat is something the 3vz really doesnt need.. Anyone wanna test their rig??