Any one seen these DIY gauges?
 

The Closed Loop Monitor

http://www.autospeed.com.au/cms/A_17...popularArticle


Air/Fuel Ratio Meter

http://www.autospeed.com.au/cms/A_02...popularArticle

I made the closed loop monitor. I had it on my 1996 Tercel (same engine as my Paseo) for a couple months. After hooking up the scangauge I noticed a huge difference in readings. Its possible I had the closed loop monitor tuned wrong, but the two showed vastly different readings.

The air/fuel ratio meter you can buy from autozone or your local parts store for $20. The bought gauge will look better, save you a hassle, and probably cost only a tiny bit more.

In regards to FE instrumentation, on a usefulness scale from 0 to 10, considering a scangauge being 10, how would you rate a combination of a/f ratio meter, closed loop monitor and vacuum gauge?

interesting.. neat diy finds

i would rate a good vacuum gage a 4. a/f and closed loop are interesting but more indicative of system health. if you get into the fuel enrichment part of the map, a/f and loop would let your know but unless you got a way to trim fuel on the fly, can't see where it would help much, still i like to watch the o2 sensor on my DVM, that's just part of the fun. Injector dwell or duty gives you actual instant % of full fuel flow per unit time, as i eluded to in another thread.

A/F Ratio
 

Having installed an A/F ratio meter (with similar LEDs), I can say that's it nearly worthless.

This was on an '03 Evo -- the LEDs would be consistent only in open loop: cold start or full-throttle. The closest use was A/F at full-throttle, full-boost (in those driving situations, a quick glance) to see if a lean situation was apparent (rare if ever).

Otherwise, the meter bounced back and forth under normal operation.

RH77 -

I have a digital A/F meter that shows me the magic 14.7 number. I got it because I wanted to "see" what an EFIE (02 sensor signal modifier) would do. But, when the EFIE is off, the A/F ratio is pretty much bouncing above and below 14.7, so it's not doing much, just like you said.

CarloSW2

123 -

I have this one :

Digital Fuel Mixture Display Kit for Cars
http://www.jaycar.com.au/productView...=&SUBCATID=347
It costs more, but I like it because I can "see" a number, so I don't have to interpret "the bouncing lights".

CarloSW2

I have a digital A/F meter that shows me the magic 14.7 number. I got it because I wanted to "see" what an EFIE (02 sensor signal modifier) would do. But, when the EFIE is off, the A/F ratio is pretty much bouncing above and below 14.7, so it's not doing much, just like you said.

CarloSW2
__________________
How does this EFIE work? What does the circuit look like? I once played around with the O2 voltage by just adding 0.2 of a volt to the signal with a 3v battery and a simple $5 voltage divider circuit and it gave me a mile per gallon or more. Did not check the placebo effect. Newer ECU's are harder to fool.
diesel

Here's the main problem with the closed loop meter (even the a/f meter)... It reads directly off the sensor... Yes, there will be somewhat of a correlation between the sensor and the ECU's response - but not directly as seen with the SG and closed loop monitor not being in sync.

The ECU decides when it's in closed loop based on sensor data it gets. It's perfectly reasonable to say that there will be moments when the sensor data is just totally bad. So the ECU works within tolerances.

I built autospeed's closed loop monitor too :D And I get the same results, the SG (which determines closed loop based on what the ECU says) and the monitor (which gets results from a wire tap) don't agree... The loop monitor fluctuates :p BUT, when the SG says open loop, the monitor generally does too.

Ok, here's another question then. If get real time fuel consumption output from the ECU, how much more useful a SG would be?

if you throw a curve to the ecu and unplug a sensor how long does it take the
SG to report the glich? just for fun

i define closed loop to be when the oxygen sensor is fluctuating between .2 and .8 volts at least once per second. but the newer the engine the larger the number of sensors have to be in agreement before the ECU is truely in closed loop. as the technology got better the tolerance around .45 vdc has gotten smaller and smaller. so what is closed for a 91 engine doesn't cut it for a 2001 engine.

diesel_john -

Here's mine :

Eagle Research EFIE Online ...
http://www.gassavers.org/showthread.php?t=5036

I will repost this as a thread in ecomodder so you can see the pictures, but this will get you started for now.

CarloSW2

I'll test that... maybe this weekend, time permitting...

As for closed loop definitions.... There's more than one... There's also quasi closed loop states depending on the data coming in from different sensors....

The term "closed loop" in it's usage here is really a misnomer for feedback controls...

Or the Compucruise - circa 1979

Functions: Speed, clock, alarm, cruise control, in/out temp, batt volt, trip, fuel consumption

http://web.telia.com/%7Eu83611035/bilder/bild281.jpg

diesel_john -

You can disconnect the 02 sensor. The car will stay in Open Loop, using the other sensors to decide how much fuel to put in. I hear this is called "limp mode", aka limp along until you get it fixed.

I think that the majority of cars have "narrow band" sensors ( 0 to 1 volt in a lambda shape, so the 14.7 "center point" is in a narrow region), like the one on my Saturn. However, if you install a fuel controller (or have a more advanced emissions system?), you will have a "wide band" 02 sensor (0 to 5 volts in a linear shape, so the 14.7 "center point" is wider and more accurate).

If I were ecomodding from scratch and knew what I was doing ahead of time, I might go for this :

AFC NEO (in the range of $400 - :eek: )
http://www.apexi-usa.com/product_ele...=260&pageNum=1
http://www.apexi-usa.com/graphics/products/2601.jpg
It's a ton-o-cash, but it bypasses so many other flaky workarounds, and it looks like you wouldn't need a ScanGauge.

Hrmmmmmm, methinks the wide-band 02 sensor (+$100 or more) is extra, :mad: .

CarloSW2

hey you found it, that part on the the left is just like the flow meter I had back in the '70's, that's the flow meter that i am trying to make over in the thread about measuring fuel flow on a carb'd engine.

any new info ????

Yah, john found his old flowmeter and is talking about it on this thread:

http://ecomodder.com/forum/showthrea...0293#post20293

Narrowband AFR meters are completely worthless.

Wideband AFR meters are highly valuable if you know how to interpret and manipulate the output.

For a fuel meter, I'd rate the SG at a 7. The other things you mentioned, the SG already does, so there's not much need for discrete components.

I have considered rigging up a little circuit to do this very thing. I was a little concerned about the A/F ratio when I did this, however. As I understand things, going a little more lean should not be a problem... This method would beat spending $75 for a EFIE gizmo.