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Old 12-04-2008, 11:30 PM   #1
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VX leanburn questions

please forgive me if this is in the wrong forum, I dont quite understand the variations of some of the forum descriptions.

anyway I have been lurking here for awhile. I have a '92 Civic VX that as of tommorow on my way to work will have 440,000 km on it. I have only been able to get 39-42mpg out of it so I wired up a digital multimetre to the O2 sensor as described in one of TomO's posts(http://ecomodder.com/forum/showthrea...s-info-23.html) and am unsure if I am getting lean burn. my normal cruise voltage in 5th gear at 80km/h(apprx 50mph) hovers between 0.550 and 0.568 which according to the TomO's thread is correct for leanburn however I have seen 1.04 volts a few times and felt a slight hesitation when it went to that and again when I leaned on the throttle enough to jump back down to around 0.55

a little more info. im currently trying to pass local emmisions test here in the greater vancouver area of BC, Canada so I have been testing things to rule them out. one thing that seemed odd was when I was testing the EGR system I was unsure how to test if the computer was actually actuating the EGR so I pulled the vac hose of the EGR and hooked it up to a vacuum gauge taped to my windsheild then went for a drive, well I got vacuum a few times but also a few times I got the 1.04 volt and hesitation with with the vacuum indication, surprisingly it didnt kick the CEL with having the EGR disconected.

I am posting here because I have had less then stelar responce on other forums(although suspended hatch has replied a couple times to my posts on civic-eg.com) which I attribute to most other forums being interested in performance not MPG and emmisions.

one more question before I head off to bed.
VX emmisions numbers. I am currently getting HC: 0.2 grams/km(max 0.5), CO: 7.03 grams/km(max 9.32), and NOX 1.7(fail, max 1.24). do these numbers jive with anyone else emmisions testing? if so what are normal numbers for you?
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Old 12-21-2008, 09:15 PM   #2
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I am startled at the lack of response to your question. This would not have happend back in the $4.00+ days. The forums here have gone quit silent with the bottom dropping out of gasoline prices.

fwiw, your mpg experience seems to be very much in line with a big group of VX owners who have never seen any consistent numbers much above ~42mpg. There seems to be another (smaller) group that states they consistently get 48-55mpg hwy. The problem is that none of them can ever explain to any of the rest of us on just how to get there. The VX is too finicky, picky, complex or other set of reasons and therefore we just don't get those numbers regardless of o2 sensors, full and complete maintenance schedules adhered to and its quiet frustrating.

Some of your specific questions are addressed in other threads and you should use search for them.
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Old 12-22-2008, 03:37 AM   #3
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Quote:
Originally Posted by SCoupe View Post
Some of your specific questions are addressed in other threads and you should us search for them.
In case the built-in site search fails to produce the results you need, you can also try this:
http://www.google.com/coop/cse?cx=01...67:6eyn0a2-udg
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Old 12-22-2008, 01:26 PM   #4
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Quote:
Originally Posted by blind monkey View Post
...one more question
VX emmisions numbers. I am currently getting HC: 0.2 grams/km(max 0.5), CO: 7.03 grams/km(max 9.32), and NOX 1.7(fail, max 1.24). do these numbers jive with anyone else emmisions testing? if so what are normal numbers for you?
reading from two past tests:

When engine had 36,409 miles on it in 1995 as measured by CARB:
HC: .28 grams per mile
CO: 9.52 grams per mile
CO2: 223.36 gpm
NOX: .035 gpm

When engine had 178,515 miles in 2005 measured at Smog Check for registration purposes:

%CO2: 15.1
o2: .1
HC (ppm): 19
CO: .02
NO (ppm): 639
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Old 12-22-2008, 06:39 PM   #5
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Not familiar with gpm...

The vacuum hose has to be connected to the EGR for it to work.

If your NOx are high on a VX first check the base ignition timing (should be 16 degrees BTDC aka the red mark on the crank pulley), the EGR (needs to be removed and cleaned out about once every year or two), and then the cat converter (you have to compare your exhaust before and after the cat to check it's efficiency. Not many shops will do the proper test. Most will want to use a pyrometer but that kind of test is inconclusive at best).
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Old 12-23-2008, 09:51 AM   #6
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Not familiar with gpm...
Grams Per Mile
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Old 12-23-2008, 09:38 PM   #7
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Yeah I know what it stands for. But I don't have a frame of reference for it as I'm used to looking at it in parts per million.

It's kind of like growing up with mph and then driving where the speed signs show km/h. Or lbs vs kg, although I'm getting pretty used to that.
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Old 06-10-2009, 07:16 PM   #8
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vx lean and hx is lean

Quote:
Originally Posted by blind monkey View Post
please forgive me if this is in the wrong forum, I dont quite understand the variations of some of the forum descriptions.

anyway I have been lurking here for awhile. I have a '92 Civic VX that as of tommorow on my way to work will have 440,000 km on it. I have only been able to get 39-42mpg out of it so I wired up a digital multimetre to the O2 sensor as described in one of TomO's posts(http://ecomodder.com/forum/showthrea...s-info-23.html) and am unsure if I am getting lean burn. my normal cruise voltage in 5th gear at 80km/h(apprx 50mph) hovers between 0.550 and 0.568 which according to the TomO's thread is correct for leanburn however I have seen 1.04 volts a few times and felt a slight hesitation when it went to that and again when I leaned on the throttle enough to jump back down to around 0.55

a little more info. im currently trying to pass local emmisions test here in the greater vancouver area of BC, Canada so I have been testing things to rule them out. one thing that seemed odd was when I was testing the EGR system I was unsure how to test if the computer was actually actuating the EGR so I pulled the vac hose of the EGR and hooked it up to a vacuum gauge taped to my windsheild then went for a drive, well I got vacuum a few times but also a few times I got the 1.04 volt and hesitation with with the vacuum indication, surprisingly it didnt kick the CEL with having the EGR disconected.

I am posting here because I have had less then stelar responce on other forums(although suspended hatch has replied a couple times to my posts on civic-eg.com) which I attribute to most other forums being interested in performance not MPG and emmisions.

one more question before I head off to bed.
VX emmisions numbers. I am currently getting HC: 0.2 grams/km(max 0.5), CO: 7.03 grams/km(max 9.32), and NOX 1.7(fail, max 1.24). do these numbers jive with anyone else emmisions testing? if so what are normal numbers for you?
if your vx is like the hx coupe the EGR routes the exhaust to the intake manifold .the hx has a cover under the fuel injector rail ,i take the cover off every 100,000 miles and clean the holes on the intake carbon plugs them up,you do have to pull the fuel injectors and rail off to access the cover 6 bolts ,i average 43-48 mpg almost 315,000miles 1997 Hx.
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