PraxRX7

The A/F gauge reads between 0 and 1.10 Volts sent out by the O2 sensor. However, it appeared that I was running leaner than normal, so I hooked up the Multimeter and it showed 1.10 V at the O2 sensor, and only 0.88 V once it got to the gauge.

I did some more testing and found that it was actually from the fact that I used the same gauge wire as on the O2 sensor, and it was heating up and therefore increasing resistence in the wire. Giving me what looked like fuel loss.

I am going to re-run the wire with 12-gauge heat taped wire and that should fix the problem.

As far as the calibration of the Autometer A/F gauge, I couldn't be happier.

Piranha

are you using a shielded wire? I was using that from radioshack; maybe that is why my A/F meter works shitty I guess I'll bust the multimeter out.

rx7_turbo2

Autometer is ****. I have seen it compared to a wideband, not only is it not even close on it's readings but it's delayed so bad that it's impossible to tune with. Save yourself the headache Prax and stick the car on a dyno with a wideband, it's not even funny how poor the Autometer is.

PraxRX7

I agree that the Autometer is the ***** for tuning. But for monitoring the system for safety it is fine.

Right now I am not in a tuning phase, if I was you bet your butt I would go get a wide band and a dyno session.

But just because of the wiring the gauge reads .1 V off just from wire resistence, then when it heats up, the resistence is sucking up 0.3 V, that is the difference from the stoich/rich line to full rich.

Just throwing out ways to help the autometer monitor things better.

Piranha

So, are you using a shielded wire?

PraxRX7

non-shielded... =(

Piranha

I was just wondering. Well, don't rely on your A/F meter too much. I hope you've had your injectors sent in at least. My motor popped because of it I think (and the A/F meter read the same )

silverrotor

iTrader: (1)

That a good point not to use the same gauge wire as on the O2 sensor, as It will heat up and therefore increasing resistence in the wire. I'm In the middle of buyinf an A/F Ratio and a 2 channel EGR gauge, Autometer. Check out this thread. https://www.rx7club.com/forum/showth...hreadid=118752

PraxRX7

I haven't sent in my injectors for cleaning, but right now there is no sign of hesitation of power loss (and that redline fuel injector cleaner is great!)

I might send them in for cleaning this winter...but that all depends on if I have time and money to rip them out and ship them out. (Already re-wired my fuel pump though...hesitation begone )

Piranha

Well, mine were off not too much, and when I hit 6K in 4th gear at about 7-8 psi, it was like I someone turned off the acceleration. My boost gauge needle was shaking. 2 Days later my seal popped. That fuel injector cleaner you buy at the store does jack ****. I put so much of that in my car. I'm never buying it again. Paying 100 is much better than paying 1500, but its your money. I didn't have hesitation or power loss until I hit that one point. Then bam.

PraxRX7

Well, I will make it a priority to send them in then

Piranha

hell yeah, I really try to get word out to people, because I had my stuff running tip top besides that, new fuel pump, rewired, fuel pressure gauge, so after spending 600 dollars on that **** I don't spend the 100 to get them sent in. A friend recommended to soak them in simple green for 3 hours at 150 degrees. While a lot of crap came out of them, apparently it didn't do ****.

silverrotor

iTrader: (1)

It's worth the hassle and Inconvience to take your Fuel Injectors (FI) out and making this a special job. I gained mysterious HP and Fuel Economy after doing this. I did this, In conjuntion with cleaning out my Manifolds. No joke, their was ATLEAST half a coffee cup full of Carbon In there. Well worth It...

Also, no FI Cleaner (through the Gas Tank) comes near to having them machine cleaned.

10TH_ANNIV_T2

If you pick the O2 sensor signal up inside the car at the ECU you shouldn't have that problem.

As far as Autometer being s**t, you have to understand what it is doing-- Simply illuminating a LED that corresponds to the voltage that it reads-- nothing more! Comparing it to a wideband to tune with is just showing your lack of knowledge. It all starts with the O2 sensor.

If you want to custom tune, you only have a few options:

A tailpipe based gas analyzer (like they use at the DMV)

An after market wideband which will include a NEW O2 sensor

Build your own www.diy-wb.com or buy it from TechEdge

NZConvertible

Yep, taking the signal from the ECU removes the heat issue, and also eliminates the risk of grounding the signal thriugh the O2 sensors shielded cable, which is usually the problem when peaple complain they're getting no signal at the gauge. Personally I think it's easier than getting a wire through the firewall too. Exactly! All A/F gauges work exactly the same, so I don't know why everyone bags just the Autometer one. My A/F meter built from a $10 DIY kit works no better or worse! Another misconception is that the sensor sends a signal to the ECU that is then used to calculate the amount of fuel required, which is wrong. All the ECU sees is whether the A/F ratio is above or below stoichiometric, and adds or subtracts fuel to move it in the other direction. It does this rapidly (several times a second) to stay as close to stoichiometric as possible only when cruising or under light load (this is called closed loop). The rest of the time it's ignored by the ECU. So the O2 sensor is really only accurate right at stoichiometric, and crap everywhere else! It does the job it was designed for very well, but sucks at what we try to use it for.
So don't blame the sensor or the gauge, because they both work fine.

AbecX

Those a/f guages suck, they barely show the correct results @ wot

Piranha

My Nordskog gauge is worse than the Autometers, it only has 10 LEDs

The whole time I THOUGHT you guys had wired it up from the ECU... I didn't understand the whole heat thing.

10TH_ANNIV_T2

NZ-- Thanks for pointing out the oversight with respect to the ECU and standard O2 sensor. I should have clarified the NEW O2 sensor comment to include a different O2 sensor. I know that the 86-88 just use a single wire O2 sensor, not sure about the 89-91.

The reference I made to the new O2 sensor suitable for use with a wideband setup was specifically to a NTK type sensor that is a different design, and when used with the correct stuff is suitable to tune with.

BTW, I did buy and receive the WB meter from techedge, but have yet to install it (trouble getting said O2 sensor). I will have to add this as a second sensor in my DP, leaving the stock O2 to feed the ECU the proper signals. For those of you that would like more info, visit http://techedge.com.au/vehicle/wbo2/default.htm