Debian Dog

Strange problem here. The dyno A/F meter said I was way lean (run 1).

So I richened it up (run 2) and this time not only did it say I went lean, the nitrous system safety kicked on and turned off the nitrous ( Thanks Venom).

So (run 3) I run N/A and it still says I am lean!!! EFILive verifying that my O2's are VERY low.

Now I hook up my wideband (LM-1) and head out on the street A/F at WOT 11.0:1 WTF!

What type of anomaly could cause this? Why is my HP so wavy?

Here is a comma delimited file of run 1 data

The graph:

ataylors

iTrader: (2)

I would hook YOUR wideband up on the dyno to see if it is really differant. Maybe your wideband is not giving you correct readings. Also if you want to get more street accurate dyno runs find a shop with a eddy current dyno like a Mustang Dyno

Team ZR-1

Well look at your right O2, 1.007 mVolt and your not even on the gas pedal and inj pulse is only at 5 so of course the O2 would be reporting hugh rich when fuel trims only report about -2% rich.

INJDC2 % HO2S21 V LONGFT2 % TP %
5 1.007 -2.3 7.5
4 1.007 -2.3 7.5
4 0.998 -3.9 12.5
4 0.998 -3.9 8.6
47 0.994 0 100
51 0.994 0 100

Debian Dog

That is injector duty cycle

Team ZR-1

The 5 is the DC, 1.007 is O2 output voltage

Debian Dog

Right... so lets pretend I am still not getting you. What are you tring to say bad O2?

Team ZR-1

If you compare left and right O2s :

HO2S11 V HO2S21 V
0.79 1.007
0.79 1.007
0.786 0.998
0.794 0.998
0.855 0.994
0.846 0.994
0.846 0.994
0.851 0.99
0.855 0.99
0.851 0.99
0.573 0.981
0.851 0.981
0.859 0.981
0.66 0.959
0.764 0.959
0.838 0.959
0.916 0.955
0.768 0.951
0.773 0.946
0.799 0.946
0.768 0.942
0.295 0.942
0.786 0.938
0.551 0.938
0.694 0.933
0.838 0.933
0.768 0.929
0.295 0.929
0.747 0.929
0.621 0.929
0.087 0.929
0.712 0.929
0.816 0.929
0.378 0.924
0.447 0.924
0.612 0.924
0.291 0.924
0.79 0.924
0.794 0.924

Left side shows lean, right side way rich.
Being I do not know which side the dyno put the wideband or which side your wideband is, we have to guess and being the dyno graph is so wavy which is seen when being too lean then my guess is the right O2 is the cause and the left O2 reporting 600-800 mVolts (lean) is correct.

Any splices or cuts/burns to the O2 wire will degrade that O2 either by destroying the internal air path in the wire or the splice itself, meaning if the O2 wire was too short due to headers people tend to extend/spilce the wires.

If the O2s are older then 30,000 miles I would change them, in any case you cannot just change one for then one is switching faster then the other so you need to replace both since the older one would be switching slower and you still end up with a off balance from left to right.

You can swap the O2s from side to side to test, if the problem then also switches then you known O2 is clearly the cause.
If problem does not also move then suspect the wires to the PCM to O2 or maybe a injector on left side is bad or a exhaust leak, something to cause it to run much leaner but if that was the case then with a scanner you should see your fuel trims also one being rich and the other real lean,

Debian Dog

Well I replaced the drivers side a few month back perhaps the passenger side is in order. Thanks!

What

Excessively rich mixtures can look lean on widebands 02s.... I've also seen excessively rich mixtures cause that sort of misfire/inconsistent graph. If you're puffing some healthy black smoke out the back on the dyno, try leaning it out... otherwise, check some of the other suggestions.

Debian Dog

Well I replaced the pass side O2 (no cats or rear O2s) and leaned it back out to 12.6-12.7 with my WB. It feels a lot stonger. I also advanced the timing a bit but picked up a hair of KR. So I am going to back that off a smidgeon and use that as a baseline. Then start adding N2O again.

What

Sorry didn't see those other squigglies/runs. I did many a dyno run once upon a time and your spark is getting blown out.

Either from the previously excessively rich mixtures (un-burnt o2 getting into exhaust especially with that bad spark and reading lean as I mentioned).

Or bad ignition.

Obviously less fuel helped, but...

What kind of plugs/wires/etc. are you using? You might want to consider a change/upgrade there as well. You should be able to run a little richer than that for street and still make decent power (safer tuning imo).