23 replies to this topic

[sspcivic31]

with Nos air fuel ratio is critical

so dont use an o2 sensor single or 4 wire to do it. those in dash afr gauges are pretty much crap. the reason being that you only have 1 volt of resolution to measure full lean and full rich condition a 14.7:1 afr(stoich) is about 638mv. the sensor is desingend to be accurate around this voltage. when you start trying to tune for a 12.5:1 afr guess what you only have 432mv of resolution to like 10:1 afr and the little light display moves all over the place till you get a strong enough signal(steady load on the motor) and by then you'll be changing exhaust valves again(if you are lucky) a true AFR meter works on a 5 volt scale with stoich around 2.5v so guess what you got over 2 volts of resolution on the rich side and 2 on the lean side.

now if your wife has access to the NGK sensors honda used on the civic (VX i believe) there are a few sites on the web that explain how to make a good AFR meter based around that sensor as it operates on a gretaer than 1 v scale. thta would be something good. i'll see if i still have the link to this site it was a diy.

[jag]

unfortunatly the wideband will not work controled by the pgmfi ecu. most widebands are on a 5 volt scale(stoich is around 2.5v) and require dfifferent power supply to run the sensor. the newer AFR meters(like the motec plm) are using the bosch lsu sensor(cheaper to procure and almost as accurate. whole meter and sensor around $1200) instead of the NTK uego (best sensor about $1200 for the sensor only no electronics.) but i am hearing the ntk is not available any longer so its a moot point i guess. leaded race gas will degrade the sensors  reliability/performance so its for tuning only unless you can afford new sensors 1-2 a season.(it needs to be stored correctly too, as womens perfume can destroy the sensor quicker than race gas) the wideband also needs  to be a few feet from the back of the exhaust valve in most cases to be accurate.

Hi,

The new techedge wideband units (and maybe some other units) have a simulated narrow band output. This allows you to connect the wideband to the factory ECU and still have closed loop control. It makes the output of the wideband look like a narrow band. Then you can connect a display (or a palm pilot or PC) to the wideband unit and have a good tuning aid. This is what I currently do in my integra although things are a little more complicated because I have a hondata setup so I put a switch on the wideband connector to switch between the wideband output (0-5 volts) and the simulated narrowband (0-1). That way I can tune the car with the wideband and then turn on closed loop and switch to narrowband. Works like a charm.

The new 2.0 wideband unit from techedge uses a VW bosch sensor that you can get for something like $29 a piece. It seems that the first batch of these sensors was defective and rather than do a recall they just made them insanely cheap.

-Jeremy

[sspcivic31]

The new techedge wideband units (and maybe some other units) have a simulated narrow band output. This allows you to connect the wideband to the factory ECU and still have closed loop control. It makes the output of the wideband look like a narrow band.

Does this cause any loading problems to the ecu on the o2 circuit? or are ther two independent outputs from the sensor through an external controller? it seems like an interesting idea but whats the operating life of the sensor?

[sspcivic31]

Techedge has some interesting things on it. i answered most of my own questions from above.
thanks. still seems that you are better off adding a bung and using the wideband independent of the o2 senor though even though they give you the option(reluctantly it seemed to me from there info) of a simulated 1v output.

[sspcivic31]

DIY wideband AFR meter

heres another site for the industrious who dont mind building there own wideband AFR meter.

edit:
this is from the Motec site reguarding the NTK(not the one honda uses) and the bosch lsu.

Both sensors have a life expectancy of 500 hours on unleaded fuels and that number is diminished to 50 hours or less using leaded fuels

Edited by sspcivic31, 04 December 2003 - 11:19 AM.

[C8V6C]

I got a B16with 2 O2 sensors but I don't have the second one plugged in. Once in a while check engine light will flash on and off, but most people tell me it is not necessary to have the 2nd one.

I know without one at all, fuel is very rich and gas mileage is down, but is there any diff without the 2nd? There doesnt seem to have a diff feel....

[sspcivic31]

I got a B16with 2 O2 sensors

the second sensor after the cat allows the pgmfi to detect degraded performance of the catalytic converter and alert of the problem through the check engine light. it was implemented with the obd2 diagnostics system. depending on the ecu you are using it may not be needed.

[C8V6C]

pr3 manual 91 JDM teg

[87sivtec]

You HAVE to run both. Do you have crappy throttle response? How about mediocre mileage? Add the second one in and reset the ecu. You will notice a huge difference. Trust me, I went through this a year ago. The easiest way is to use the stock exhaust manifold as it has both bungs there. Otherwise you will have to weld in the second bung.
I have the same ecu as you. This ecu reads the signal from 2 pairs of cylinders and will modify the fuel to the appropriate pair of injectors. 1/4 and 2/3 are the pairings. With one O2 sensor the ecu is reading the signal as if it is from ONE pair and adjusting the fuel to one pair. The problem with that is generally one pair goes really rich and one pair goes really lean. It does this because the computer will adjust the fuel and then looks for the resulting change in the exhaust. When it doesn't see much change, it will lean or richen even more. This results in bad throttle response and pretty bad gas mileage.

You may notice that your car runs great when at wide open throttle though. This is because the ecu is ignoring the O2 sensors at that time.
You will enjoy driving your car much more when you add the second one in.

The only other option is to switch to another OBD system. OBD1 uses only 1 O2 sensor.