I just got my first readings using my DIY-WB. One thing I noticed while in closed loop, my readings don't center around 14.7, they seem to be around 15.5. Is this within margin of error or is there a problem somewhere? I am pretty much exhaust leak free in front of the WB. I could post my log if needed.

 

I'm of no help here because my idle AFR is up to 16.5:1 -> 17.5:1 using the O2 constants ... .. . AND THE EXHAUST IS STILL STINKY!!!

Tim

 

I uploaded a log here. http://home.comcast.net/~bdimitroff/Gm030601.csv
My free air voltage reading is around 3.93, which I believe is normal. Any ideas?

 

I took at a look at the log file and noticed what you are seeing. Near the end at idle the WB was reporting an even leaner AFR (16.8-17.1).

You didn't mention the method of data logging, although I think it is through the ECM.

Check that the UEGO side ground is only tied to the ECM. This is important as the ADC inputs are single ended. The UEGO side power can be from the same source as the heater power.

The heater side power and ground need to be tied into the vehicles electrical system away from the ECM wiring. The DIY-WB is designed with this in mind. There are separate power & ground feeds for each of the two circuits (heater & UEGO).

Other things may be from NB & WB sensor placement, what kind/brand of NB sensor is in use, and the actual ECM calibration constants.

RBob.

 

Oxygenated fuel?
Some refineries are mixing leftover chems into regular batchs.
Are you using a scope?, or something with a sampling rate?, if so what rate of sampling?, it the timing really optimsed?, just a few degrees off, can effect the residual O2 in the pipe.
Winter gas?.

What do the plugs look like?.

How old is the O2 sensor the ecm is using?.

It the engine using any oil?. Which can lead you astray tune wise.

The WB as good of indicator as it is, doesn't mean there aren't outside influences at work.

 

My NB is in the drivers side header and the WB is in a bung right after the y on my SLP headers/y-pipe. The NB is a normal single wire Bosch. All o2 constants are unchanged from stock AUJP settings. Both the heater and controller circuits are being run off the cigerette lighter, how do you suggest I wire it up, change the UEGO ground to a ground pin on the ECM? Also, could the 24 gauge solid core wire on the Ip, Vs, gnd, and Calr connections cause this?

 

I was writing up my reply to Bob's post while you posted Bruce. I am most sure we still have winter gas around here. If anything, the plugs look a little rich, but I am not an expert plug reader, a main reason for the WB. The motor doesn't use oil, but does only have 7k or so on it, when the heads were off 2k ago, the crosshatch didn't look worn at all. Timing is very close to stock AUJP at part throttle, but I'm sure it is far from ideal for my current setup. I have Moates scanner to update 5 times a second, if thats what you mean by sampling rate.

 

The 24 awg on those sensor leads will be OK, the current levels are small. You do need to move the UEGO controller ground from the cigarette lighter to a ground feed into the ECM. Just that one ground line needs to be moved. This allows the DIY-WB Vout to be properly referenced to the same ground that the ECM's ADC is using.

I'm not too keen on Bosch O2's, or a non-heated O2 in headers.

RBob.

 

Now you might want to play with the timing.

 

Thanks Bob, changed the controller ground and readings are right around 14.7 during cruise. Idle reading are still around 16.5 which might explain why it is so rough.

 

This is an interesting topic, I would've never thought to relocate my ground for my WBO2 to the ECM ground

Right now I have it grounded to the body near the battery........

should I move it???

 

Which WB are you using? And how is the output (AFR Vout) being used?

RBob.

 

Right now I'm just watching the display while driving, and when I use the WB hac for data logging

It is a PLX setup. It does have a narrow band output, but I am not using it just yet.

I just find it interesting that when my integrator is around 126- 130 and my blm's are in the 126 - 130 range, my WB is showing an average afr of 13.9 at idle. Just wondered if this might have an effect on it or not.

 

Right now I'm just watching the display while driving, and when I use the WB hac for data logging

It is a PLX setup. It does have a narrow band output, but I am not using it just yet.

I just find it interesting that when my integrator is around 126- 130 and my blm's are in the 126 - 130 range, my WB is showing an average afr of 13.9 at idle. Just wondered if this might have an effect on it or not.

 

I wouldn't use that unit. Also, unless it has an analog ground that is separate from the heater control you will never be able to data log the AFR accurately.

RBob.

 

Well it has two grounds, one that I have running to the cig lighter ground, and the other to what I thought was the ECM ground by the battery

As for accuracy, I'll have a chance to verify it when I throw it on a dyno and see how it compares to the shops WB

I'll post up the results once I know for certian

Thanks for the heads up on it though

Now if it is way off, is their a stand alone setup like the PLX that is recommended? Or at least a set criteria to purchasing one?

I barely have time to tune my car let alone try to build the DIY WB setup