Weird LC1 or HPT readings?

[TT_Vert]

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 in closed loop (15.8-16.3)
* 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 is +/- .6 of commanded AFR
* Output from HPT, Moates meter and Logworks is the same

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?

That is what I do not get. IF I put it into open loop AND clear fuel trims (o2s not oscillating) i'm VERY near commanded AFR, the second I put it into closed loop the fuel trims go to around -8.6 yet 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.

I thought it was the 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. Ive taken the MAF out and cleaned it gently so I doubt that is the issues. What else is disabled in open loop that would skew fueling?

This obviously has something to do w/ closed loop but I'm not sure what.
Opinions?

Attached a few logs showing open loop w/ fuel trims cleared and commanded AFR Vs. actual.

[TT_Vert]

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).


What can I do to resolve this? Am in in the right area R/L voltage to try to compensate for O2 sensor placement?

Dave

[262]

Looking at your scan I see your TPS is at 4-5% but it looks like you are just idling and not moving.

Second do you reset the fuel trims half way through the first log? If so your afr's go rich indicating to me your tune is not correct.


Long tubes will screw with your stock o2's some but with a cam that has -11+ degrees of overlap you shouldn't be running into this issue.

Would you mind pm'ing me a copy of the tune if you don't want to post it?

[TT_Vert]

Looking at your scan I see your TPS is at 4-5% but it looks like you are just idling and not moving.

Second do you reset the fuel trims half way through the first log? If so your afr's go rich indicating to me your tune is not correct.


Long tubes will screw with your stock o2's some but with a cam that has -11+ degrees of overlap you shouldn't be running into this issue.

Would you mind pm'ing me a copy of the tune if you don't want to post it?

I did reset the trims mid log to monitor the affects on AFR. I am idling, I double checked my TPS percentage in older logs to verify previous TPS when I was actually at 14.7 idle AFR and it was 5%. I will attach a copy of my tune to this post if possible. The tune was perfect the last time out before the long tubes. Trims are always between -1 and -5, afr WAS at 14.7 at all points looking at old logs and the car runs/drives perfect w/ amazing fuel mileage and ZERO issues (even now). When I go into open loop the fueling is pretty deal on w/ the commanded fueling, wouldn't that indicate that my tune is pretty accurate since it runs off the VE table instead of sensor feedback?

I see what you're saying about test.hpl being lean when in open loop but in test2.hpl the commanded afr is +/- .2 from 14.7 when in open loop w/ trims cleared. Not sure why it would vary from log to log like that.

I have modified PE, MAF frequency to get my trims better at lower airflows and the VE tables. For the sake or argument, I attempted to revert back to the stock VE and MAF frequency tables and while it did change trims, the trims ALWAYS pulled it back to 16.2ish. Thank you for your help this has me mystified.

Dave

[TT_Vert]

Ttt...

[5_Liter_Eater]

fuel trims being negative or positive in closed loop doesn't have much to do with it. Once the fuel trims settle in the closed loop AFR should average 14.7 whether the fuel trims are positive or negative. I fought a ~15.5:1 closed loop AFR problem for a long time and what it ended up being for me was tiny pinhole air leaks around the WB bung. If your WB is reading leaner than 14.7 in closed loop check your WB bung and anything in between your stock O2's and WB for air leaks, even very small ones will throw it off.

[TT_Vert]

Turns out it was a pinhole leak in the wide band bung. I figured it was something like that. Now back to 14.7-15.0

Dave

[5_Liter_Eater]

Sweet! I think this may be a pretty common thinig for those who are seeing leaner than normal closed loop AFR's.

[262]

Car sounded good and sounded like it was running well saturday night at strats when you left. I was going to ask you about it but we pulled in with our two tbss's as you pulled out