Who replaced his LAF sensor (O2 sensor, Civic Vx)? - Fuelly Forums

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Old 11-12-2007, 11:13 AM   #1
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Who replaced his LAF sensor (O2 sensor, Civic Vx)?

I am trying to get information about a possible relationship between a defective LAF sensor and a malfunction in "lean burn"


So, I have three questions :

Why have you replaced this LAF sensor?

Have you seen a difference in "lean burn", after replacement of this sensor? (Does the engine seems to work better in "lean burn", or not?)

Do you have a response time when you accelerate at low load and low RPM (with old / new sensor) ?


Thanks
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Old 11-12-2007, 11:41 AM   #2
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I have driven two different VXs now with recently replace sensors. Both have the same "response delay" and get about the same mileage now.

I think a good rule-of-thumb for the LAF is not to replace it until you are getting poor mileage or you have a CEL for it being faulty. They just cost too much to warrant replacing them for any other reason.
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Old 11-12-2007, 12:28 PM   #3
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I just replaced mine, but don't have a baseline for mileage. Hell, I don't even know when I enter lean burn... Would be nice if a lean burn light came built in.
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Old 11-12-2007, 01:52 PM   #4
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Quote:
Originally Posted by Danronian View Post
Both have the same "response delay"
Is this exactly the same problem as me?
->
Quote:
Originally Posted by VEI
Here is a example :
http://fr.youtube.com/watch?v=IiTz8jA7fWM
(It is a climb). I push slowly on the pedal but the car doesn't accelerate, there are some small hesitations. Suddenly, with the same constant pressure, the car accelerates faster.
Quote:
Originally Posted by Danronian View Post
I think a good rule-of-thumb for the LAF is not to replace it until you are getting poor mileage or you have a CEL for it being faulty. They just cost too much to warrant replacing them for any other reason.
Yes, it?s true.
But, sometimes, I have the CEL (5 times a year).
And I think that my ?response delay? is more brutal than before.
I have controlled a lot of sensors (MAP, TPS, LAF), ignition, fuel filter, ... All seems to be OK.
So, I don?t if I must buy a new LAF sensor.

Quote:
Originally Posted by Matt Timion View Post
I just replaced mine, but don't have a baseline for mileage.
Ok, but when you drive at low load and low RPM, is there a difference with the new sensor?
Is it more pleasant to drive in these conditions?
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Old 11-12-2007, 03:17 PM   #5
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VEI YOUR LAF IS NOT WORKING PROPERLY AND NEEDS TO BE REPLACED.

Your lag and stutter is NOT normal lean burn operation. Your car is exhibiting classic symptoms for a bad o2 sensor. No two ways around it. What Danronian was describing was normal lean burn operation which is a fairly subtle stumble upon acceleration, but nothing like what you are describing. Hope that clears it up! You need a new o2 sensor.

When you replace your o2 sensor, your car will no longer do the sudden power surge you have described. My car was doing this before I replaced mine. And it sounds like mine was not as bad as yours and yet I noticed a big difference with the new o2 sensor. You will notice a VERY big difference with a new o2 sensor. Where you should be putting your energy now is figuring out where you are going to get your new o2 sensor. Because they are expensive and not all work properly. Good luck! Wish I could steer you in the right direction but I really don't know where to point you since you are in Belgium! You could try the $79 one I bought, but seems like a bit of a gamble.
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Old 11-13-2007, 07:32 AM   #6
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Quote:
Originally Posted by 1993CivicVX View Post
VEI YOUR LAF IS NOT WORKING PROPERLY AND NEEDS TO BE REPLACED.
I know your opinion. But I would have several answers, several opinion before make a choice.

Ok, you have not this problem with your new sensor, but sometimes, you have the CEL. Your AFR is perhaps a litle diff?rent, more rich. I don't know.

It's difficult for me to explain my problem.
With the new exhaust manifold (no cat.), the accelerator response is different. The "response delay" is more "brutal".
But before, with d15z1 exhaust, I think I already had a "response delay" and some hesitations in lean burn. (More that when I bought the car).

Maybe I am crazy. It is possible that this is normal. I don't know.
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Old 11-13-2007, 07:45 AM   #7
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I agree with 1993CivicVX, replacing your LAF would be the first step, especially since you've been getting the CEL code for the LAF. That is your computer telling you that the LAF isn't working properly.

Might I suggest that you de-carbon the engine as well. See if your local Honda dealer has the Top Engine Treatment (basically seafoam) or use seafoam. There is a link on how to use the seafoam/de-carbonizer in the VX links in my signature. Do that right before you replace your LAF and install your Catalytic Converter. That will help with the stumble.

Have you cleaned your EGR and EGR ports? If not, this can cause some stumbling on acceleration as well. There is also a How-To in the VX links as well.

You should also think about getting a replacement Catalytic Converter just for emissions sake. To save money you can get an aftermarket one for a regular civic and have a muffler shop, or yourself, install it after the exhaust manifold.

Once you've done all that you should be good.
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Old 11-13-2007, 08:02 AM   #8
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I agree with 1993CivicVX, replacing your LAF would be the first step, especially since you've been getting the CEL code for the LAF. That is your computer telling you that the LAF isn't working properly.

Might I suggest that you de-carbon the engine as well. See if your local Honda dealer has the Top Engine Treatment (basically seafoam) or use seafoam. There is a link on how to use the seafoam/de-carbonizer in the VX links in my signature. Do that right before you replace your LAF and install your Catalytic Converter. That will help with the stumble.

Have you cleaned your EGR and EGR ports? If not, this can cause some stumbling on acceleration as well. There is also a How-To in the VX links as well.


I agree, sounds like some sound advice to getting your z1 working smoothly. While you're at it, I would also pull off the IACV (on the back of the intake plenum, facing the firewall) and make sure it's not clogged by spraying some intake cleaner into it. With that cleaned out, and the above suggestions put into place, the only other thing it could possibly be is that your timing is off.

If you have a timing light, you might want to check that and adjust it according to Honda's recommendation. The timing being off can also make your car stumble when accelerating.

edit:
With your different exhaust manifold, where is your LAF mounted? If it is too far away from the exhaust ports, the sensor might be taking too long to heat-up and stay warm, making it read incorrectly. I know on some aftermarket headers they have the 02 mounted behind the motor. For the LAF, I think this wouldn't be an ideal location for it at all.
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Old 11-13-2007, 09:27 AM   #9
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Dan, thanks for adding in the IACV cleaning, I forgot about that.

The LAF is located at the collector just about 7-8inches down from where the OEM manifold would've had it located. Shouldn't be a big factor since it's still close enough and reading all the ports. Besides, that is what the heater circuit is for in the LAF as well.
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Old 11-13-2007, 10:26 AM   #10
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Might I suggest that you de-carbon the engine as well. See if your local Honda dealer has the Top Engine Treatment (basically seafoam) or use seafoam.
It?s very difficult to find this kind of treatment in Belgium.
And they often have a bad reputation.
Sometimes, this can be bad for a old engine. This can cause a loss of sealing (The carbon can maintain compression).

I have tried this product last year : http://www.wynns.be/product.aspx?nav...4&p=55964&l=EN


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Have you cleaned your EGR and EGR ports?
Yes I have cleaned the EGR.



During one week, I have drove without EGR. But no difference.


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Originally Posted by TomO View Post
You should also think about getting a replacement Catalytic Converter just for emissions sake.
Last year, I have passed the pollution tests successfully.



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Originally Posted by Danronian View Post
I would also pull off the IACV (on the back of the intake plenum, facing the firewall) and make sure it's not clogged by spraying some intake cleaner into it.
I have checked the IACV. It?s seems to be clean.

Quote:
Originally Posted by Danronian View Post
If you have a timing light, you might want to check that and adjust it according to Honda's recommendation. The timing being off can also make your car stumble when accelerating.
I have checked this. It?s good.


Quote:
Originally Posted by Danronian View Post
With your different exhaust manifold, where is your LAF mounted? If it is too far away from the exhaust ports, the sensor might be taking too long to heat-up and stay warm, making it read incorrectly.
Before :


Now :
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