Does EGR valve matter?

[imzjustplayin]

Originally Posted by tjts1

And that reason is that lean AFR causes much higher NOx emissions. The EGR is necessary for the car to have any chance of meeting an emission standard.

The Lean burn does not function unless the EGR is functioning, regardless of its purpose. EGR isn't used just to limit emissions, it's also used to cool the intake charge which can help with preventing detonation. The VX engine is pretty finicky, just missing a few components or having certain things not running optimally is enough for it to not get the mileage it's suppose to. However in the OP's case, 33mpg, I feel it's because he does not actually have a CX/VX transmission, problem is, he is in denial about that... A VX w/o lean burn gets slightly worse (at least 3mpg, not A LOT WORSE (10mpg+) mileage.

[dieselbenz]

EGR can't cool intake charge because exhaust gas is obviously much hotter than the fuel/air mix going into the engine. EGR does reduce peak in cyl temp by reducing the % O2 in the intake.
You also said that lean burn does not happen without EGR. Great. Now how does the ECU know that the EGR is functional? Usually there is a temp sensor in the EGR pipe. This is why a block off plate at the exhaust end of the EGR pipe usually causes a CEL light to trigger. But if you block it off at the intake manifold after the temp sensor, problem solved.
cheers

[imzjustplayin]

Originally Posted by tjts1

EGR can't cool intake charge because exhaust gas is obviously much hotter than the fuel/air mix going into the engine. EGR does reduce peak in cyl temp by reducing the % O2 in the intake.
You also said that lean burn does not happen without EGR. Great. Now how does the ECU know that the EGR is functional? Usually there is a temp sensor in the EGR pipe. This is why a block off plate at the exhaust end of the EGR pipe usually causes a CEL light to trigger. But if you block it off at the intake manifold after the temp sensor, problem solved.
cheers

Like I said before, the EGR in the Civic VX is far more sophisticated than you know. The purpose of the EGR in the Civic VX is far more important than that of a Lexus LS400 where you can in fact just block off the plate and shouldn't notice much of a degradation in much of anything except emissions. The Civic VX has an EGR Control box and various wires and sensors going to the EGR control valve and whatnot. Even worse, even if you DO have the EGR all legal and ****, hooked up and everything, completely stock but because the car is so old and wasn't completely maintained, with even a single EGR component clogged or not operating 100%, then lean burn will work intermittently or not at all. Let me stress to you that EGR used in the Honda Civic VX is far different from that of any vehicle you've worked on and any preconceptions of how the EGR is used and isn't used can be basically thrown out the window. It's very common for the Civic VX to have NON FUNCTIONING lean burn thanks to various small things going wrong.

If you don't believe that the EGR is an essential component, why don't you go searching around for people troubleshooting their Lean-Burn in their Civic VXs and you should quickly discover that one of many problems with the Lean-Burn is the EGR not fully functioning..

I know you hate the EGR, some how you think it's bad but it's not and it does serve its purpose, especially in the Honda Civic VX. I don't know why you have to insist it's useless when you don't even own one of these vehicles nor have had any experience with them. ****, to be frank, I think this discussion is totally irrelevant because the OP's problem isn't the lack of lean burn or the engine running improperly (hopefully it's running fine) but he's got the wrong transmission in there which would account for a far greater mileage disparity than he would ever know.

[briogio]

Ok "player", I have a stock CX manual transmission, I bought the car from the original owner and he never changed it, and nor have I, period. Maybe my non-stock tach is to blame or maybe my tires and wheels are causing the disparity. Anyway if lean burn only improves mileage 3%, I'll move on to aerodynamics. It'll cost me quite a bit of money and hassle, (EGR valve, 5 wire O2 sensor, exhaust manifold, then wiring it all up, all for 3%? I don't think so!
Thanks for the input guys I've learned a lot.

[theholycow]

His point was not that your transmission was changed, but that it no longer matches your engine (which was changed).

Until you put in a VX transmission you're wasting your time and will never see decent fuel economy. I imagine that the relatively torquey VX engine becomes very wasteful when run at unnecessarily high RPM.

Edit: Is the CX transmission the same as the VX? I thought the VX had its own transmission that wasn't available in other models.

[imzjustplayin]

Originally Posted by briogio

Ok "player", I have a stock CX manual transmission, I bought the car from the original owner and he never changed it, and nor have I, period. Maybe my non-stock tach is to blame or maybe my tires and wheels are causing the disparity. Anyway if lean burn only improves mileage 3%, I'll move on to aerodynamics. It'll cost me quite a bit of money and hassle, (EGR valve, 5 wire O2 sensor, exhaust manifold, then wiring it all up, all for 3%? I don't think so!
Thanks for the input guys I've learned a lot.

What? Non stock tach? Why didn't you just get a gauge cluster from another vehicle and install it? If you DID do that, maybe calibrate it! To calibrate it, you need a stand alone tachometer which you hook up to the car, and then to adjust the tach on the gauge cluster, you very carefully with a fork remove the needle and re-install it. This works both for calibrating the speedometer and tachometer. Don't try this with the temperature or fuel gauge because you'll break them! But there is no need to "calibrate" anything if your tach shows your car idling at around 700 because you can't.. Why don't you take a picture of your car's tachometer while it's idling? If it's spot on when it's idling?

What was your MPG BEFORE the swap?? I insist you don't have a CX/VX tranny based upon the information you posted in that other thread, and based upon the information you gave me, the numbers actually nearly perfectly align with having a DX/LX transmission, not a CX/VX.
Lean burn doesn't improve mileage 3%, more like 10%+, however if your car is getting 33mpg, it's not because of a lack of lean-burn I can say that much!

[briogio]

Originally Posted by *************

What? Non stock tach? Why didn't you just get a gauge cluster from another vehicle and install it? If you DID do that, maybe calibrate it! To calibrate it, you need a stand alone tachometer which you hook up to the car, and then to adjust the tach on the gauge cluster, you very carefully with a fork remove the needle and re-install it. This works both for calibrating the speedometer and tachometer. Don't try this with the temperature or fuel gauge because you'll break them! But there is no need to "calibrate" anything if your tach shows your car idling at around 700 because you can't.. Why don't you take a picture of your car's tachometer while it's idling? If it's spot on when it's idling?

What was your MPG BEFORE the swap?? I insist you don't have a CX/VX tranny based upon the information you posted in that other thread, and based upon the information you gave me, the numbers actually nearly perfectly align with having a DX/LX transmission, not a CX/VX.
Lean burn doesn't improve mileage 3%, more like 10%+, however if your car is getting 33mpg, it's not because of a lack of lean-burn I can say that much!

Ok put in a stock gauge cluster tach unit=hassle, put in aftermarket tach=simple, and since I'm stupid I prefer the latter.
It's idling at 750rpm and I have no reason to believe it's not accurate. I went to that Fatboy site and lo and behold even putting in my wheel & tire size, 2,500rpm should equal 76mph, but in my Canadian CX it equals 100kmh (60mph), so you're right "player" dude!
My mistake saying 3% and not 3mpg.
My old (450,000kms) D15B7 was getting better gas mileage than my JDM D15B VTEC-E swap; mind you with no EGR, no 5 wire O2 sensor, and the wrong ECU (P08 instead of instead of correct P07). I never actually broke it down exactly, (mpg), but I've been doing my same commute for 10 years, so I know. Now I'll make all the proper component additions in my own sweet, (read cheap), way. I'm getting great info from this site, EcoModder, and the rest of the web family.

[imzjustplayin]

Originally Posted by briogio

Ok put in a stock gauge cluster tach unit=hassle, put in aftermarket tach=simple, and since I'm stupid I prefer the latter.

How exactly is putting in a stock gauge cluster a hassle? Hopefully I'm missing something extremely obvious but aren't the wiring harnesses to the cluster the same for all the vehicles? I think I'm going to have to probe the Internet for this information because for all I know, it's plug and play and after taking out my cluster, I know it's easy as hell to remove..

Originally Posted by briogio

It's idling at 750rpm and I have no reason to believe it's not accurate. I went to that Fatboy site and lo and behold even putting in my wheel & tire size, 2,500rpm should equal 76mph, but in my Canadian CX it equals 100kmh (60mph), so you're right "player" dude!

CANADIAN!?!?!?! Oh ****... The "Canadian" CX is very different from the U.S. CX. ****, they don't even have an LX there like we do here. From what I've read, the CANADIAN CX has the same gear ratio as the DX/LX here in the United States which proves my point perfectly. Essentially, what comes in the U.S civics is different from what comes in the Canadian Civics for a given trim level, however when servicing the cars, they're exactly the same. I guess you can say it's like comparing the Toyota Corolla with the Chevy Prizm.

[GasSavers_BIBI]

[QUOTE Oh ****... The "Canadian" CX is very different from the U.S. CX. ****, they don't even have an LX there like we do here. From what I've read, the CANADIAN CX has the same gear ratio as the DX/LX[/QUOTE]

On 92-95 civic model, also in Canada, has the same transmission then the VX. The transmission on my VX is a CX, and runs the same as the old VX tranny.

By the way we also have LX.

[deschlong]

Just for reference, eh:

The Canadian Market (CDM) 92-95 Civic CX has the same engine and the CDM and USDM DX - that is to say, the D15B7. Which means it ALSO has the same transmission that comes on the D15B7. Canada DID NOT get any vehicle with the D15B8, which is the tiny motor that came in the USDM CX, and that shares the same transmission gearing with the VX.

Here is a very rough translation comparing the models in both countries:

3DR
US = CA
CX = DX
DX = DX
VX = VX
Si = Si

4DR
US = CA
DX = LX (Also have a LX Special Edition)
LX = EX
EX = EX-V

2DR
US = CA
DX = DX (Also have a DX Special Edition)
EX = Si (Without power windows/locks)