TT_Vert

iTrader: (12)

At first I thought it was the LC1 but I'm not so sure now. At WOT my AFR is right at 13.0 where it is commanded yet at idle and part throttle it is way lean (According to the LC1). Being that my trims are -8.6 I would think it would be rich now and the ECM is pulling 8.6% of fuel right? Well I tried to play w/ my VE tables but they really didn't affect the AFR much.

Few things I noticed:

* -8.6 trims yet reading lean.
* Reset fuel trims, afr in 14s but as trims learn and go negative AFR gradually rises back to 16 or 17 again.
* Commanded AFR logged and says 14.63
* Turn closed loop off afr to 12.2 to 12.9 or so.

This is a different motor this year but I still don't think things are jiving as fuel trims are negative yet it is reading way lean. The o2s are oscillation like they should, car runs perfect at part throttle, idle and WOT. Perhaps my wideband is goofy but at WOT it is perfect. I tried a calibration on the LC1 to no avail. When I put it in closed loop and it reads lean, it is reading just from the VE tables and MAF frequency for idle fueling correct? Or am I missing something obvious here?

Thanks
Dave

YellowToy/A

iTrader: (1)

If o2s are oscillation like they should then they will be 14.7sh where they cross 0. Check to see what the WB reads there. If it is far off your wb has a problem. If it has a problem there it will be off at WOT. Be safe not sorry. Rich is safe. Lean is hot.

TT_Vert

iTrader: (12)

That is what I do not get. IF I put it into open loop (o2s not oscillating) im somewhere in the 14s, the second I put it into closed loop the fuel trims go to around -8.6 and it goes way lean. Check out this log and check the o2 oscillation vs. wide band value. I have verified the output of the wide band using log works, my moates and the input into hpt.

GregRexAdams

You may have oxygen sensors going out. Drove me nuts on a car I tuned. I would reset everything and it would drive perfect, but by the time he got home it was starting to surge and the AF was off. The oxygen sensor(s) was bad and shifting the tune. We turned them off and it fixed it. New sensors are the cure.

TT_Vert

iTrader: (12)

My car drives 100% fine that's the odd thing> I thought O2s for a bit but they thought that since both banks are doing the same thing, either both are going bad at the same rate or perhaps the MAF is the culprit as it controls fueling for both sides. Opinions?

Dave

TT_Vert

iTrader: (12)

Anyone?

TT_Vert

iTrader: (12)

So it seems any time I manually clear fuel trims and put it in open loops AFR is fine, closed loop it goes lean, any input anyone? What could really cause this?? Same tune and setup as last year.

Dave

jimmyblue

iTrader: (11)

If you have a big cam the idle AFR reading and the real
in-cylinder air/fuel can differ, any air blown through to
the exhaust will bend the reading. A pressurized inlet
would only magnify this. But I would expect the
narrowbands to be affected the same way.

I would try to correct it (presuming you know what is
really stoich, and that you really want to idle there)
by the O2 sensor switchpoint tables (vs airflow mode,
so you need to follow airflow to airflow mode) and
get it to where you want by raising the mV since you
are indicated-lean. From what I've seen there is a
couple of points' worth of range there, like I pulled
a truck from about 13:1 to 15:1 by moving his from
450mV to 300mV in the low flow cells.

TT_Vert

iTrader: (12)

The thing is, this exact tune and set up last year netted me 14.6-14.8 AFR at idle and all part throttle. Now it is in the 16s except in open loop when it is near where it should be. Could it possibly be a bad set of o2s or maybe my maf on its way out after sitting for the winter?

Also one other question. Is the commanded AFR that is logged displaying the AFR after ALL multipliers have been implemented?

Dave

edcmat-l1

iTrader: (10)

If you've got some overlap, it's normal.

TT_Vert

iTrader: (12)

if it was normal, it would have done it last year w/ the same exact combo that I have this year. It did NOT. I'm trying to recall at what point I Put my long tubes on. Perhaps I put them on after i did my last scan where AFR was at 14.7ish at part throttle and idle. Perhaps that is part of my issue. It certainly idles a lot better when I put it into open loop and AFR is near 14.

TT_Vert

iTrader: (12)

Well I went ahead and tried to change R/L voltages by adding 200Mv and even tried to subtract when adding had no affect. I even went as far as to add 400 just to see what would happen but nothing w/ the AFR changed (o2s sat at a stready .800 Mv) . Still 16.2 ish in closed loop. The second I put it in open loop and reset trims, I'm w/in .2 of my commanded AFR. I'm so lost currently, any more input would be appreciated. This was my stock o2 Sensor B1/B2 R/L vs. Airflow Mode. for reference.
Labels 0 2 4 6 8 10 12 14 16
Rich/Lean Voltage 450.84249 450.84249 380.69030 440.82075 500.91723 525.95460 525.95460 525.95460 525.95460

What I'm noticing is that no matter what I do the trims try to pull it back to 15.8-16.2 on the wideband. SO what I'm assuming is that the narrow bands are for some reason seeing stoichiometric as 15.8-16.2 is. Maybe because they are in long tubes and perhaps because the o2s are older? I clear trims and force it into open loop and I'm right back near commanded AFR. I command the AFR manually in HPT and it gets very close to what I command as well (until I get to commanding 12 or 16 then it is off a slight bit (.5-.6).

Dave