ZBoater

Well, here it is, for better or for worse, a Defi A/F ratio gauge installed and connected to the lower OEM stock oxygen sensor. Click on the pics for a much larger view.





Ok, so here are my observations. Bear in mind I am a complete newb, so these are just observations, not professional comments or suggestions. I would like for someone who knows more than me to comment on these so we can all learn a bit. And, please, I've already read countless posts on wideband, dedicated O2 sensors, yadda yadda yadda, so please, lets keep those to a minimum, shall we?

My observations:

1. It seems to take a minute or two for the gauge to start working. Warmup of the sensors perhaps?

2. The gauge seems to like 14.6 (one peg above the 14.5 mark). The gauge always returns to that reading after fluctuating under varying driving conditions, but it seems almost rigged to always come back there. Being that the gauge only reports from the signal it gets, and the signal wire is connected to the 02 sensor, I can only assume that the ECU is somehow managing the air/fuel ratio to always be at that level.

3. Under WOT with the foot on the gas the gauge seems to lower sharply into the 10 range (10 is the minimum). As soon as I release the gas pedal, it swings all the way up to 17 (17 is the maximum. There seems to be a 1-2 second lag between my actions and the gauge response. This swing is temporary and very short - the gauge always comes back to 14.6.

4. While cruising the gauge sticks to 14.6, fluctuating a bit into the 13, 12.5 category a bit, but always coming back to 14.6. When I brake and depress the clutch, the gauge goes to 17 momentarily and comes right back up to 14.6.

5. The shift I am in seems to impact the gauge reading, for example, when I do something stupid like brake slowly from 80mph down to 25mph (like a toll booth), I accelerate but I am still in 6th gear. The gauge goes nutso into the 10 range, but I am not moving much. All these spikes are very temporary (1-2 seconds). The gauge slowly comes back and settles again at 14.6.

Well, there it is, for what its worth. I like it, I think it looks cool.

narkotic

iTrader: (3)

Yep, pretty useless.. The motor on that thing will probably wear out, which is why most light show narrowband gauges utilize LED's, not a needle. 14.6 is a stoich mixture of air and fuel which is why you see that alot. You could actually make this gauge useful if you got a wideband O2 sensor w/ a narrowband gauge output.

zachcrosen

iTrader: (23)

1. My AEM wideband does the same thing. Sometimes on very cold mornings, it will take a minute or 2 to start working.

2. My AFR at cruising speeds is always 14.6 =/1 maybe .4. I think 14.6ish is stoic or something like that for NA engines.

3. Mine AEM does the same thing.

4. Does the same thing again. It goes beyond 17 because of less fuel and more air being supplied.

ZBoater

Here is another pic of the gauge at night...

zachcrosen

iTrader: (23)

I am having the same gauges installed with my SC and I love how yours looks at night.

FairladyZ

Looks really nice. What was the purpose though, just for show?

ZBoater

Well, I kept reading lots of posts about running lean because of NA mods, needing ECU reflash, yadda yadda yadda. I have the intake, plenum, header, cats and exhaust mods, and I've dynoed several times with the A/F ratio coming out fine. But, being paranoid, I figured I could cheaply tap into the existing sensor and see what the ECU is seeing.

Plus, it can't hurt at the next car show!!!

FairladyZ

yep it looks clean!

G3po

iTrader: (8)

I actually use the DEFI-D A/F driven from the output of my Innovative LM-1 ,
Analog WB output. The motor isn't going to "wear out" any faster than any other digital "stepper gauge". The LM-1 combo pretty well; however, the Software provided with th LM-1 only allows a "linear" Lambda to Analog output curve. Ideally you need a per cell mapping function. The guage mostly serves two purposes , rough WB A/F inidcation and cosmetic (I have all 5 other DEFI-Ds as well. For tuning I dump the LM-1 to laptop.

PS, I think the DEFI-Ds look better "without" the black ring installed, but I have a Willow interior on my G.

gringott

iTrader: (17)

How did you route the wire to the sensor?

myz8a4re

iTrader: (2)

subscribing

ZBoater

That is one of the disadvantages of paying someone else to do it for you - you miss details like this one. He did say it was easy to route the sensor wire from the gauge into the engine bay through an opening above the clutch. From there I have no idea how he routed it to the sensor.

Madelinot

iTrader: (1)

Don't the 2004.5 and 2005 models have a WIDEBAND O2 sensor stock? I thought that they replaced all the sensors on the ULEV2 cars...

Please correct if I'm wrong.

Thanks!

G3po

iTrader: (8)

Pre-cat yes , post cat no.

AvengerZ

iTrader: (3)

whats a plenum?

uplz4588

so cant you just tap into the precat sensor? so the defi would become a wideband?

bullseye

Looks good, but have you tried taking that black plastic cover off of the brushed aluminum bezel? It comes right off. It will match your other gauges better if you remove it...

james840a

iTrader: (7)

Hi, im getting ready to install my autometer narrow band gauge tomorrow. And looked at the service book. I see there are 4 wires to the O2 sensor. One is + one is - but im not sure witch is the signal wire, there are 2 wires going to the ECU.