Egr Important Or Not!!?!!

Post by **slw240sx** » Wed Sep 04, 2002 4:18 pm

hey i ve watched this board for monthes an monthes now an soaked up plenty of knowledge but i havent been able to find a answer to one of my questions, my EGR valve is disconnected underneath it an the hose is tattered an possible cloged what types of performance effects could this cause i know my car has been slugish on the start an its getting very old like 155000 mile an its not as strong as it used to be but could this be a vacum leak effecting that ... there seems to be no other symptoms from the unpluged valve that im aware of could some one please educate me here!!!!!!!!! thanks :help

YouTube · Post by **EZcheese15** » Wed Sep 04, 2002 4:18 pm

EGR is your Exhaust Gas Recirculation valve.

It recirculates some exhaust gasses back into the intake. If it's not doing this, it will not change performance, but will simply hinder emissions.

The reason cars have EGR valves is so that exhaust gasses get sent back through the intake so that they can burn again, producing better emissions because more of the energy gets converted to power.

Post by **slw240sx** » Wed Sep 04, 2002 4:18 pm

thats basicly what i thought but, would having it missing a hose connected casue a vacumn leak since its not all in a closed loop i guess, does that make any sense? since i know a vacumn leak can lead to slugish starts or rough idle

YouTube · Post by **EZcheese15** » Wed Sep 04, 2002 4:18 pm

It depends what hose.

If the hose that is loose is a vacuum line going to the EGR valve, then yes.

If it is the actual EGR tube that runs from the exhaust back into the intake, then no. UNLESS, there is a whole in your intake where your EGR valve goes. If you have it plugged in anyway, then you have no vacuum leak, because the stuff coming out of the EGR tube is going to be after-engine air, basically an exhaust leak.

But if you don't have the intake plugged, then yes, normally exhaust gasses would be recirculated back into the intake, but in this case, the engine is pulling in air from not only the air filter, but also further down the intake tract. The problem with that is, it is pulling in unmetered air because it is after your mass air flow meter. This will cause you to run lean, because you are pulling in more air than what the car thinks, so your air:fuel ratio is higher.

Basically, if you see any loose vacuum lines, they should probably be connected, unless you have done some modifications to your car that prevent you from connecting them.

Post by **Chris69427** » Wed Sep 04, 2002 4:18 pm

Quote »The reason cars have EGR valves is so that exhaust gasses get sent back through the intake so that they can burn again, producing better emissions because more of the energy gets converted to power.[/quote]

This is only partially correct. When I first got the TA I had to deal with the EGR system extensively and got to know it very well!

The EGR system recirculates semi spent exhaust gases back into the intake to cool down the combustion charge! It reduces the temperature ever so slightly in the combustion chamber and this prevents NOx compounds from forming. As a downside, this system makes more hydrocarbons which means if you overdo the EGR (as I did) you'll still fail on the HCs, meaning you're running rich and some unburnt fuel is coming out of your exhaust pipes, which tells me that an EGR system reduces the efficiency of your engine in order to reduce the nitrous oxides (NOx) your car produces...

Unless it will wreak havoc on your computer or cause you to fail emissions, (and there are ways to trick the computer with a $2 resistor from Radio Shack) I would rip out your EGR system b/c it is hurting your performance by reducing your engine's efficiency!!!

Other than that, EZcheese15 answered your vacuum leak questions, but I just wanted to throw in my two cents about the EGR system which also does what EZcheese said and more...

YouTube · Post by **EZcheese15** » Wed Sep 04, 2002 4:18 pm

Thanks for the extra info! It's always nice to learn more

Post by **AunVoh** » Wed Sep 04, 2002 4:18 pm

i know my car is runnig lean and its throwing an engine code, so i should undo my EGR? i did this in my s13 and it fixed the problem... but i forgot how to do it :-\ someone please tell me again

Post by **technoman** » Wed Sep 04, 2002 4:18 pm

AunVoh wrote:i know my car is runnig lean and its throwing an engine code, so i should undo my EGR? i did this in my s13 and it fixed the problem... but i forgot how to do it :-\ someone please tell me again

If it's running lean. it wont run lean for too long.How do you know it's running lean?

YouTube · Post by **EZcheese15** » Wed Sep 04, 2002 4:18 pm

AunVoh wrote:i know my car is runnig lean and its throwing an engine code, so i should undo my EGR? i did this in my s13 and it fixed the problem... but i forgot how to do it :-\ someone please tell me again

You need to check what the code is before you assume anything. The light can come on for a million different reasons. EGR is just one of them.

Post by **Chris69427** » Wed Sep 04, 2002 4:18 pm

If you're running lean, do NOT disable your egr, you'll run even more lean (read my post carefully above...); if anything replace the poppet gaurd thingy on the egr valve with a larger one for MORE egr and you'll richen the fuel mixture a little... but yeah, first check out that code; lean is far worse than rich!

Post by **AunVoh** » Wed Sep 04, 2002 4:18 pm

yes yes, i know that lean is very bad, i'm not a noob for godsake, i think its the erg because the ecu is reading a code for the EGR, and i think its lean because it's turning the plugs white......

Post by **slw240sx** » Wed Sep 04, 2002 4:18 pm

thanks for the input guys im just going to get under tha hood an start replacing majority of my vacumn hoses i have a day off an got nothing better to do thanks again

Post by **ka24de_510** » Wed Sep 04, 2002 4:18 pm

I can tell you for sure that removing the EGR will not turn off the ECU code. Mine lit up when I took it off. My engine seems to run a little lean too.

I'm thinking about replacing my o2 sensor with a resistor once I figure out what the desired value should be. that way I can tell the computer that my engine is running lean and it will adjust with more fuel. should be good for a little performance boost too. horrible on fuel economy, but if I wanted that I would own a geo.

YouTube · Post by **EZcheese15** » Wed Sep 04, 2002 4:18 pm

You can't just replace an O2 sensor with a resistor, it won't work. The O2 sensor is constantly fluctuating between .1 and .9 V (for the up stream O2). The downstream also fluctates constantly depending on the reading (different voltages, and a smaller fluctation, but the same concept). If the ECU sees a constant input of say .5 V (which is stoichometric), then it will still see it as a problem.

The only solution is to get a O2 sensor fooler from a company that makes them for this purpose already. They are made to fluctuate randomly and simulate an O2 sensor's readings, rather than a constant voltage signal. You can normally find these at places that sell off road modifications stuff, like for Jeeps and stuff.

Post by **ka24de_510** » Wed Sep 04, 2002 4:18 pm

darn it. just when I thought I was on my way to a sensor-free engine.

I researched them after I made that post, and unfortunately, like always, Torry is right.

however, early this morning I think I discovered my problem. the previous owner who swapped the engine into my car moved the O2 sensor from it's original location to the place where the EGR tube used to mount up. this creates an issue though, because the way the tube is set up, it doesn't appear that the o2 sensor fully extends into the exhaust flow. this should, if I'm not mistaken, constantly tell the engine it is running rich, because the sensor never detects much oxygen.

now I have a new problem. the o2 sensor was moved for a reason; it doesn't clear the steering box. and neither the header nor the steering box will be easily moved. does anyone have an idea how much it would cost to get a new hole put in my header (stock) and get it threaded to fit an o2 sensor? I could tap it myself, but I have a feeling the tap and die set will cost more than having someone do it for me, and I can't weld.

Post by **ka24de_510** » Wed Sep 04, 2002 4:18 pm

oh, and AunVoh, unfortunately I can say with near certainty that this is not the same problem you're having. at least not unless you enjoy randomly rearranging various engine parts.

Post by **AunVoh** » Wed Sep 04, 2002 4:18 pm

no, it's not the same problems as i am having :-\ mine are more likely caused by the fact that God hates me and wants me to fall in a hole :-[

Post by **technoman** » Wed Sep 04, 2002 4:18 pm

A good muffler shop should do it for around 40 dollers.

YouTube · Post by **EZcheese15** » Wed Sep 04, 2002 4:18 pm

I had one installed in my exhaust by a local muffler shop. It was $20, including the bung and also a plug.

Don't try threading it yourself. You need to have a bung welded in. If you thread it yourself, the wall of the exhaust is not thick enough to make any threads, and your sensor will come out.

Egr Important Or Not!!?!!

Egr Important Or Not!!?!!

Nissan Forums

Infiniti Forums

Datsun Forums

Technical Forums

Classifieds / Marketplace

Nissan Motorsports

General Forums