I've been running my autometer a/f gauge for about a month or 2. The cars been bogging and I thought it was my dizzy that I had just replaced. Everytime I pounded my car it would bog out under load and the a/f gauge would drop till there's no reading. I disconnected it the other day and it runs a helluva lot better. Feels like I gained 20 HP! lol I had the gauge tapped right by the ECU. I guess I'll try tapping closer to the O2 sensor. Either that or trash this thing.

 

very interesting. never heard this problem before. keep us posted.

 

don't tap the a/f gauge at the ecu...its a bad spot to tap at since you will be changing the voltage the ecu sees and the voltage swing of an o2 sensor is very small.

if you do tap the o2 wire, tap as close to the sensor as possible. personally i would run a dedicated o2 sensor for the a/f gauge. actually i would run a dedicated wideband o2 to a techedge or fjo display.

 

breaka_1_9, how is tapping it closer to the sensor going to make a difference? Wouldn't the ecu read the same voltage no matter where you tap it at?
Please enlighten me.

 

don't go disrespectin ya elsers now, boy. the wideband idea is good, and plus, those A/F guages are nothing but junky lightshows, IMO

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 22lbGS-R &raquo;</TD></TR><TR><TD CLASS="quote">don't go disrespectin ya elsers now, boy. the wideband idea is good, and plus, those A/F guages are nothing but junky lightshows, IMO</TD></TR></TABLE>

Sure a wideband reading would be nice but if you've looked in to the DIY WB projects things get very expensive. I'm sorry but you are a moron for saying they are junky lightshows, when boosting your A/F gauge can save your engine from total destruction

 

You should tap into the O2 sensor wire as close to the sensor as possible, and you should also ground the meter as close to the O2 sensor as possible. When hooked up correctly you see exactly what the ECU sees.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by beta13 &raquo;</TD></TR><TR><TD CLASS="quote">

Sure a wideband reading would be nice but if you've looked in to the DIY WB projects things get very expensive. I'm sorry but you are a moron for saying they are junky lightshows, when boosting your A/F gauge can save your engine from total destruction </TD></TR></TABLE>
You don't have to tell me about boosting, my last engine put out 409 to the wheels. I have had tons of experience with a/f gauges, and i feel that EGT gauges are much better. sure, widebands are expensive, but when you are spending upwards of $10,000 on an engine, you don't mind buying something nice. just my .02, and my opinion. there is also no reason to call me a moron for giving my educated opinion, grow up.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by REDBARON &raquo;</TD></TR><TR><TD CLASS="quote">breaka_1_9, how is tapping it closer to the sensor going to make a difference? Wouldn't the ecu read the same voltage no matter where you tap it at?
Please enlighten me.</TD></TR></TABLE>

azroth pretty much hit it on the head. the reason you tap close to the sensor is that you end up with 2 parallel paths where the voltage drop along each path is the same.

if you tap in a series way (o2 -&gt; ecu -&gt; a/f gauge) you will get a voltage drop at each connection point (the ecu and the a/f gauge). in this case the ecu doesn't see exactly what the o2 sends out for a voltage.

 

My autometer a/f gauge works great and I like it. I tune by it and it's pretty accurate. I havn't noticed any bogging under throttle that I didn't get when I didn't have the gauge and I have it tapped near the sensor in the engine bay.

Works for me, just don't hook the gauge up with power wires going to your stereo or you will see your a/f gauge move with bass also.


Modified by technine at 8:42 PM 4/10/2003

 

I was planning on running a dedicated wideband O2 when I go turbo. I also plan on running an EGT gauge. But since I had the gauge I just put it in along with a brand new O2 sensor. Like I said in my original post, i'm probably going to tap closer to the sensor. I'm also going to try grounding closer to it.

Does anybody know where I can get a wideband O2 sensor?

thanks for the help

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by photonjedi808 &raquo;</TD></TR><TR><TD CLASS="quote">Does anybody know where I can get a wideband O2 sensor?

</TD></TR></TABLE>

try going to autozone or napa and getting one for a honda civic vx. the vx o2 is supposedly a 5 wire wideband.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by breaka_1_9 &raquo;</TD></TR><TR><TD CLASS="quote">

try going to autozone or napa and getting one for a honda civic vx. the vx o2 is supposedly a 5 wire wideband.</TD></TR></TABLE>

unfortunately napa, autozone, or any other general autoparts store will have it on national backorder (through NTK themselves). the best source for the sensors seems to change daily, so your best bet is to stay updated on this dedicated message board: http://groups.yahoo.com/group/oz-diy-wb/

keep in mind, you cant just grab the wideband sensor; you will also need the controller and a display, both of which are relatively inexpensive through techedge. (www.techedge.com.au)

for those of you saying a wideband is too expensive: you should have thought of that before going FI if you dont own a wideband, you better at least fork out the money to tune on a wideband dyno. thats like buying a car and not having money left over for insurance.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by breaka_1_9 &raquo;</TD></TR><TR><TD CLASS="quote">

azroth pretty much hit it on the head. the reason you tap close to the sensor is that you end up with 2 parallel paths where the voltage drop along each path is the same.

if you tap in a series way (o2 -&gt; ecu -&gt; a/f gauge) you will get a voltage drop at each connection point (the ecu and the a/f gauge). in this case the ecu doesn't see exactly what the o2 sends out for a voltage.</TD></TR></TABLE>
Breaka_1_9, I'm still not sure on how you're wiring up the guage.
This is the way I have it. I'm basically taping into the O2 wire that's going to the ecu, just like a "T". So it's O2---guage wire---ecu, in the form of a T.
Is this the correct way??

 

REDBARON. That is right, but you want to T it off as close to the sensor as you can, also I cant stress the grownd enough, it needs to be as close to the O2 sensor as possible.

 

basically you want the | part of the T to be as short as possible and the -- part of the T to be the long part.

 

Breaka_1_9, I understand how you guys are saying to tap into the O2 wire, but I'm wanting to get an explanation as to why that is. I'm under the assumption that no matter where you tap into the O2 wire, you are still going to have the same voltage. If this is not true, can you please give me the reasoning behind it?

 

the only way i can think of describing it is in electrical terms. its kind of basic circuit analysis (this is based on 4 years of electrical engineering, so it seems basic to me).

here is a circuit diagram. the first one is the gauge and ECU hooked up in a T format and the second is when you tap off the ECU wire for the a/f gauge.


basically there is a"law" that says components wired in parallel have the same voltage drop across them. see the top circuit diagram.

the "law" also states that when components are wired in series, the voltages must add up to zero. the o2 sensor sends out 1V and the 1V is distributed equally (this may not be the exact case...it is just an example) among each part. so the 0.5V is seen by the ECU and 0.5V is seen by the a/f gauge which is not what the o2 sensor send out originally.

does this make more sense?

 

Breaka, it does make sense. I actually took a few electronic engineering courses in college.
But just like you said, in a parallel circuit, the voltage would be the same throughout the circuit.
So how is moving the T closer to the O2 sensor going to make any difference in what the ecu reads??
Get what I'm asking?

 

the further away you move the T point, the less the circuit looks like a parallel circuit.

 

Well. . .to get back to the original question. . .

When I put an A/F in my car a while back, I hooked it up like you at the ecu, and it totally bogged down. After messing with it for a while, found out that it was just that I'd used too large a gauge of wire. I guess it was trying to draw too much or something?? Anyways. . .I switched it out for a smaller gauge wire, and it ran fine ever since.

Don't know if that'll help or not. . .but that was my experience.

 

I did the blue wire mod with my afc to see the air fuel ratio and tapped into the o2 wire near the ecu. So far no problems and reads accurate.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Slimer89 &raquo;</TD></TR><TR><TD CLASS="quote">I did the blue wire mod with my afc to see the air fuel ratio and tapped into the o2 wire near the ecu. So far no problems and reads accurate. </TD></TR></TABLE>

how do you know if it reads accurate? did you compare the output of the o2 itself versus what the ecu/vafc sees?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by breaka_1_9 &raquo;</TD></TR><TR><TD CLASS="quote">

how do you know if it reads accurate? did you compare the output of the o2 itself versus what the ecu/vafc sees?</TD></TR></TABLE>

mines multimetered

 

i guess I'll try running smaller gauge wires