air fuel ratio gauge ???'s

[original balzer]

How usefull are they really? I can see where it would be great during initial tuning to set the mix and stuff but after that is it worth anything?
Would it be worth installing a wide band and gauge in the truck?

I plan on getting a a-pillar gauge pod for trans temp and probably a vaccume gauge for fuel milage reasons.

Honestly I have seen them in friends rides before and some of those guys claim its NESSISARY for nitrous use. However I think the ones I have seen have been narrow band (knowing the guys and the cost of wide band tends to tel me also) and Im not even sure they was useful. They seamed to be just a flickery light for ricers to oogle at.

So some people swear by them some people never even seen one LOL
Heres my thoughts let me know if I am on track here or way off base.

I would think on a road trip I could run at max vaccume and on the lean side of the AFR and that would show me where the best MPG are?

Would a missfire (fouled plug or the like) show up as rich on the AFR gauge?

Would a dirty fuel filter show up as lean?

I converted my 94 to a carb because of the healthy engine build. This is the highest performance engine I have ever tried to daily drive so I would like to keep an eye on as much useful info as I can. It still has an O2 sensor in the exhaust (I assume a narrow band being an OBD1 Truck) There really isnt anything computer controlled on my truck any more. Its all still in there because I dont know if the gauges will work without it.

At any rate I havent ever used this gauge and dont fully understand how much info it can give me or how useful the info really is to me as a human. I understand the computer uses the info but does it do me much good to know whats going on?

 

[sweetk30]

http://coloradok5.com/forums/showthread.php?t=292300

 

[496truck]

I can see it being useful for the long term if you are constantly making changes, tuning, or upgrades to get the most out of your engine. Like a street/strip car or something like that.

As an example, I just bumped up the boost on my old 740 to about 10psi. Had to install a vac/boost gauge to know exactly. I could probably go a few more psi safely before having to add bigger injectors or custom computer programming etc... The only way I would know is with a wideband and A/F gauge. The wideband would tell me where and when it's leaning out so that I could add more fuel as needed to keep the engine from going too lean and going boom.

In your case, with a carbed engine, it would be useful for the initial tune. and as long as no more changes were made or needed then it's just another gauge in the panel. About as useful as a temp gauge. It's there, it'll give you a clue if something is going wrong.

 

[Blue85]

I've tried the gauge on a narrowband and it didn't tell me anything - just flashing lights. I have a gauge on a wideband in the K5 and it works great. The WB sends a 0-5V signal to the ECM for real use and then a 0-1V "emulated NB" signal to the gauge. If you're going to make tuning changes, it's a real good idea. How else can you quantify what you are doing?

The thing is, ignorance is bliss. I hunted down problems that I honestly didn't notice when the gauge wasn't there. The truth is that lots of engines go well away from stoich under transient conditions, but they run fine that way. The gauge is useful for figuring out when something has changed and fast enough to flick a little when a misfire occurs.

Keep in mind that O2 sensors are not really A/F sensors, so they can mislead you. If you get misfires from being too rich, the sensor sees the unburned oxygen and gives a lean reading. A Lambda sensor can read from about 10:1 - 20:1, but an engine can conceivably operate some outside of that range. There are also compromises in mounting location. Can you measure both banks with one sensor or do you need 2? Pretty much every WB is heated, so it will work a little ways back, but it makes your control loop slower.

 

[four_by_ken]

After initial tuning, they are not of much use unless you have a motor that REQUIRES a lot of fuel, like a Turbo application.

 

[Blue85]

Agreed. I don't think anybody without a lot of tuning experience should try to tune a forced induction setup without a WB. The WB sensor is also an advantage for every day operation of the engine. However, the original topic is about gauges and I would go one step further and say that the gauge is not a good tuning tool either, by itself. You need to know the RPM and MAP/MAF that any given AFR goes with to do any good. The gauge is just a general visual indicator that you aren't hitting regions that are too rich or too lean. If the gauge does tip you off, you still need to break out your laptop or other tuning tool to get datalogs or something to determine where to work.

Having said all of this, I like the gauge. I look at it just for confirmation that it is rich under acceleration and lean at cruise. I do have a tuning computer touch screen mounted in the truck, but for the most part I just leave it on the media player interface. When the gauge is in the right range I know that 1) the O2 sensor is heated up and working (so the ECM has good info), 2) it's not misfiring and 3) fuel pressure is fine. Could I get by without it? Yes.

 

[Blue85]

Agreed. I don't think anybody without a lot of tuning experience should try to tune a forced induction setup without a WB. The WB sensor is also an advantage for every day operation of the engine. However, the original topic is about gauges and I would go one step further and say that the gauge is not a good tuning tool either, by itself. You need to know the RPM and MAP/MAF that any given AFR goes with to do any good. The gauge is just a general visual indicator that you aren't hitting regions that are too rich or too lean. If the gauge does tip you off, you still need to break out your laptop or other tuning tool to get datalogs or something to determine where to work.

Having said all of this, I like the gauge. I look at it just for confirmation that it is rich under acceleration and lean at cruise. I do have a tuning computer touch screen mounted in the truck, but for the most part I just leave it on the media player interface. When the gauge is in the right range I know that 1) the O2 sensor is heated up and working (so the ECM has good info), 2) it's not misfiring and 3) fuel pressure is fine. Could I get by without it? Yes.