Civic VX

I have a 1993 Honda Civic VX (non-Calif model). I am having problems passing a smog check because NOx values at 15MPH are too high. I know the problem lies in my EGR system. The EGR valve is not opening because the EGR solenoid valve does not receive a signal from the computer (ECU). I have verified the operations of the EGR valve and EGR solenoid by jumpering a direct wire to the battery. When I do this the EGR valve and selonoid works great. I do NOT get any Check Engine light to help me narrow down the problem. Any help is greatly appreciated.

altezza999

Check your O2 sensor...........and here you go.


http://www.asashop.org/autoinc...s.cfm

dwnthehatch

iTrader: (1)

I have plenty of working vx parts. See my sig. if you need anything.

Civic VX

I bought another new NTK O2 (5-wire) sensor and installed it. It did not help. I pulled the ECM and was able to back-probe the white wire (D14) from the O2 and signal ground (D22). I am getting 0.7V with the key turned to ignition with engine off. After starting the engine and letting it idle for 2 minutes the voltage went to 2.8V. Driving around with the voltmeter causes the voltage to fluctuate from 2.1 to 3.2V. The Helm manual states that this value should be between 0.1 and 0.9V. Anyone know if the ECM has been known to generated this bias voltage.

n1div

I have spare VX ecu for sale. im me if interested...

Civic VX

How much do you want for it? I just need a stock one (unchipped or modified).

EE_Chris

The VX 5 wire wideband sensor is NOT like a 4 wire variety that outputs a .1-.9v - your O2 and ECU are probably good.

Have you tried cleaning the EGR valve? Can't they become carboned up which would mean less exhaust gas getting through it which would result in higher than normal NOx levels??

Civic VX

Yes, I tried cleaning the EGR valve with Isopropyl Alcohol. I later discovered that the EGR was not opening at all. No vacuum present from the EGR Solenoid Valve. All functional testing have been done and confirmed that the EGR system should be working. It is just that the computer is not sending the signal for it to open the valve.

EE_Chris

Since you can manually activate the solenoid - have you verifed wiring integrity with a meter for the EGR circuit? Perhaps a wire has become open or shorted.

Civic VX

I was able to jumper a wire on the ECM (A11 and A26) to get the EGR valve to function. I could feel the engine almost stall when doing this. The vacuum gauge did not register any readings but when I pulled the vacuum hose from the EGR valve I was able to feel suction from the hose. It was very small but the vacuum was there.

n1div

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Civic VX &raquo;</TD></TR><TR><TD CLASS="quote">How much do you want for it? I just need a stock one (unchipped or modified).</TD></TR></TABLE>

$50 - Virgin status.

Civic VX

Can you give me the model number on the side of the ECU? I just want to make sure it is the right one. Also, can you priority mail it to me for $50 shipped?

n1div

let me check the # tonight. I can probably go in half with you on priority shipment. Just email me at: lm_22t@hotmail.com to go on with this transaction instead of using bandwidth here. I don't think IM will work since you are a trial user.

turtle-eg

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Civic VX &raquo;</TD></TR><TR><TD CLASS="quote">I was able to jumper a wire on the ECM (A11 and A26) to get the EGR valve to function. I could feel the engine almost stall when doing this. The vacuum gauge did not register any readings but when I pulled the vacuum hose from the EGR valve I was able to feel suction from the hose. It was very small but the vacuum was there.</TD></TR></TABLE>

Jack up the front wheels and have someone drive the car up in the air and see if the ecm opens the egr valve. Some honda ('89 prelude for sure) needs a VSS signal to operate the egr.

Redline96LX

Oxides of Nitrogen form because of high combustion cylinder temperatures. EGR recurculatres exhaust gas, cooling temperatures in the cylinder. Fix this soon, as excess heat in the cylinder will cause premature wear.

Charlie Moua

iTrader: (3)

<FONT SIZE="3"> <FONT COLOR="blue"> Good thread for me.

I'm doing a VX "complete" swap into my 95 civic sedan lx. I just had a few question.


1) what part of the vx EGR are you suppose to clean? any bolts you need to take off?


2) Where does it bolt onto in the engine bay?
(since my lx did not come with one)

</FONT> </FONT>

Charlie Moua

iTrader: (3)

ttt

garyhgaryh

Hey, I know this is an oild post, but did you ever figure out the problem? I'm in the same scenario as you. My EGR works - applied vacuum and the car almost stalls. I checked my solenoid by putting full voltage on it and checked for vacuum. The thing is, the EGR is not opening during cruise so I'm failing the 15mph Nox test. If I blimp the throttle, I get vacuum for a second. Keeping it running, the EGR is not open at all (no vacuum). Looks like I'm not the only run having this issue....

I failed Nox and replaced my intake. Took two days to do this. And that wasn't the problem. I just need my EGR valve to open slightly at 15mph..

Help!
Gary

garyhgaryh

Oh man I pass smog today!

Prev tests:

MPH HC CO NO
15 9 .02 1826
25 8 .02 1635

Today's test

MPH HC CO NO
15 38 .09 185
25 19 .05 178

I cut my NO by 10 folds!!!

So, how did I do it?
Of order of importance, I think:

1. timing from 16 to 13 deg
2. clean EGR passageway by replacing intake with a known good one (I would put that as #1 but my intake was not completely clogged when I tested it)
3. cleaned carbon from intake ports on the engine and new intake (esp near the injectors)
4. new plugs - one step colder gapped at .041-.043; original one was probably 5 years old and had a gap of .60-.70 when taken out
5. New air filter (probably did nothing - I should have kept the old one in since old dirty filter will increase HC (which is what I want).
6. Cleaned EAVC (screen plugged) - not sure if this can affect NO

I went in early before temps hit 100 deg. Last time I warmed up the car for 30 minutes driving it on the highway. Not this time. I drove it to the test only station 5 mins away turned it off and waited. Engine cold when the guy arrived. This should be #3.5.

My goal was to richen up the mixture somehow. I think retarding the timing helped, but not sure how it affects gas mileage. Since it's a commuter, I will probably advance it back to stock or higher.

Anyways, this smog saga has come to a close for me. I spend so much time on it that I was getting frustrated and was wondering if it was worth it. Since I commute about 120 miles/day, I can say it was worth it.

Gary


Modified by garyhgaryh at 9:58 AM 9/3/2007


Modified by garyhgaryh at 5:47 PM 9/3/2007