Installed EGR...Interesting Effect on EGT

[jdub]

Installed my EGR valve today...had to in order to pass AZ emissions. Re-set the ECU and took the car out for a run and noticed a significant change in the EGT reading on my Apexi gauge.

Previously my EGT would read ~700 deg C at 80 MPH steady cruise with 15-20 in/hg vac. Under 15 psi boost from a stop, EGT would climb to ~750 deg C and fall back as MPH stabilized in the 60-70 range.

Today (after EGR install) EGT would read ~600 deg C at 80 MPH steady cruise with 15-20 in/hg vac. Under 15 psi boost from a stop, EGT would climb to ~700 deg C and fall back to 550-600 deg C at 60-70 MPH.

That's a 100 deg C difference at cruise and 50 deg C at boost. AFR was/is 14.5 to 14.7...under boost 10.5-11.0...no change with the EGR installed.

It appears the EGR has a HUGE impact on EGT...I knew the EGR's primary purpose is to reduce cylinder temps to keep NOx emissions in spec, but I didn't realize how big the difference is. Chalk up another reason to keep the EGR.

 

[JustAnotherVictim]

Yay for research.

 

[supra90turbo]

muy interestado

 

[johnathan1]

muy interestado

Actually...it's "muy interesante"...interestado means "interstate". :biglaugh:

Yay for me and my three years of high school Spanish!

 

[Figit090]

john....NERD!! j/k . i'd have my third year if other classes didnt get in the way...and if i had the passion for the language. didnt put enough into it to get much out

interesting info though....dunno how much it effects the N/A's but i think differently about that thing now.

of course...the reset ECU didnt have any effect on the expirament did it? one thing shoved down high-school scientists' throats is keeping a CONTROL.

could the change in the ECU's program effect the engine enough to effect operating temps?

if so..you'll have to test again....once after your car has learned how to work itself around you with and then without the EGR since you reset it. lol....sry i couldn't help myself.

 

[wingman]

hm...interesting. looks like I may be slapping one in mine, even when I go FFIM. I can deal with a little extra stuff in the bay when temps go down THAT much.

 

[Insidious Surmiser]

my question then would be why did the japanese go w/ out it, and why did their motors make a very light bit more power (or so it was rumored) because i'm under the assumption that the jdm 7m makes about 240 bhp

 

[shaeff]

rumor, my friend.

-shaeff

 

[Blackmk3]

facelifts make the few extra hp not jdms, ive gota jdm and it sure dosent have the egr...seeing those figures almost makes me wanna install one

 

[lagged]

my question then would be why did the japanese go w/ out it, and why did their motors make a very light bit more power (or so it was rumored) because i'm under the assumption that the jdm 7m makes about 240 bhp

wow. keep the bullshit spewing to a minimum ok?

 

[IJ.]

Would have been interesting to see a before and after dyno run with AF Mapping, these results sort of explain why some have reported detonation after removing it!

 

[jdub]

Figit90 - I thought about the ECU Re-set myself. But, I've re-set it multiple times over the past few weeks in an effort to keep a consistent base. My problem is NOx...HC and CO are very low (< 25% of AZ standard). I was trying to enrich the mixture in order to keep the temps down since that is what produces NOx. The best I was able to do was 2.96 gpm NOx (AZ Std is 2.50 gpm)

My problem is I have very limited ability to change fuel. I have an AEM EMS sitting here and really don't want to spend the $$$ on a MAFT or SAFC. So, I was attempting to change the mixture with fuel pressure and the Remier style adjustment screw on the Lex AFM. I had very limited success...the stock ECU just compensated.

The last emissions run produced a NOx of 3.22 gpm with the same low HC and CO. That is the run I based the above pre-EGR EGT and AFR numbers on. The ECU was re-set prior to that run as well and ran for about 2 weeks...they have been consistent since the re-set. While my observation doesn't have the usual scientific controls, I believe the numbers are accurate. The EGT didn't fall due to the mixture being rich.

I read a post JetJock made concerning the EGR...originally it was designed to help reduce detonation. Seeing the effect that it had made me a believer...the reduction in temps was very significant. The incidences of detonation IJ is talking about would be easy to occur if you had the motor tuned with an EGR and then removed it without changing the tune. Sudden increase in cylinder temp with the stock ECU richness removed with an SAFC = detonation.

IJ - I would have like to see dyno runs too! According to my "butt dyno", I can't really tell a difference in power. The car is still barking 2nd under boost on 275 rear tires w/ an auto tranny. Same acceleration as far as I can tell.

 

[lagged]

Would have been interesting to see a before and after dyno run with AF Mapping, these results sort of explain why some have reported detonation after removing it!

IIRC the EGR valve is closed during WOT.

 

[Squid699]

yeah i think it only helps at partial throttle.

 

[miekedmr]

If the throttles wide open, you want as much air/fuel mixture to get in there as possible, so any recycled exhaust gas is just going to be wasting space and reducing power.

 

[Insidious Surmiser]

wow. keep the bullshit spewing to a minimum ok?

i havn't been told otherwise, up till now... :dunno: what'd'ya expect???

 

[3p141592654]

They go without it because it reduces cost and is not needed to certify the car, no other reasons.

my question then would be why did the japanese go w/ out it, and why did their motors make a very light bit more power (or so it was rumored) because i'm under the assumption that the jdm 7m makes about 240 bhp

 

[Insidious Surmiser]

makes sense... then i guess egr goes back on, next time the engine's out

 

[Squid699]

Greensboro, huh? I drove through there on my way to the Charlotte Auto Fair. You make it out?

 

[lagged]

i havn't been told otherwise, up till now... :dunno: what'd'ya expect???

dont post if you dont know