Calc VE QC check and questions

[Strong05]

Never mind, finally got the LC-1 to work (serial to computer, analog has always worked) by downloading the latest software... go figure.

Brad

[Strong05]

Just made another run with recommended changes to check for O2 functionality. This time the car ran in normal CL. From what I can tell it looks like they are working, but then again I don't really know what to look for.

Thanks again for helping me out with this!

Brad

[WeathermanShawn]

Yes, that log looks pretty good.

Your O2 sensors look real good. I don't see an issue there.

On your next log (if necessary) we can probably drop the O2 sensors and re-add the MAF Frequency. That will help in ironing out Table B5001.

Your VE Table looks pretty good. The 400 Rpm row can probably be ignored as that does not look representative. Whats interesting is that the 'slope' of your VE Table is pretty gradual. I see you got it up there in Rpms..I bet that warmer IAT is hurting a little. Your LTFTBEN correction was close to 1.00 (ideal) as possible.

In reality it is closed to done. You can always post up your tune and I can give you an example on smoothing out the VE Table.

One more run and its done!

[joecar]

+1 O2 sensors are functioning correctly.

What Shawn said: drop HO2S11/HO2S21 and add MAFFREQ for your next log... can you also add EXT.WO2AFR1 (you may have to edit the V2 options to do this).

+1 calculated VE is rising very gradual.

+1 LTFTBEN looks good.

Notice that DYNCYLAIR dips down in the range 3200-4200 rpm... this indicates your actual VE table does this, I'm interested to see DYNCYLAIR after you paste in the calculated VE.

[Strong05]

+1 O2 sensors are functioning correctly.

What Shawn said: drop HO2S11/HO2S21 and add MAFFREQ for your next log... can you also add EXT.WO2AFR1 (you may have to edit the V2 options to do this).

+1 calculated VE is rising very gradual.

+1 LTFTBEN looks good.

Notice that DYNCYLAIR dips down in the range 3200-4200 rpm... this indicates your actual VE table does this, I'm interested to see DYNCYLAIR after you paste in the calculated VE.

Joecar,

I added back in SAE.MAF and CYLAIR to the PID's. I don't have a serial WO2 connection but I did log the analog WO2 (table E on my log file, if that transfers over). I applied the VE corrections to the attached tune from my latest run (also attached), however I haven't applied the MAF corrections yet. Although I must say all of the MAF corrections thus far have been very minor, only a tenth at the most.

So what does the low VE mean? I noticed that it is significantly lower than what is programmed in for a stock 02 so far in almost every sector.

Shawn,

The warmer IAT was due to heat soak (left it idling for a while to warm up), after about 10 minutes the IAT drops to 20 C.

Thanks again both of you guys for helping me out with this!

Brad

[WeathermanShawn]

Brad:

I'll look over your work this evening.

It looks like you have a segment of your LTFTBENS that are ~3-5 % positive. One easy way to alleviate this problem is as follows:

With the Scan Tool (ignition on) under Calibrations is a Tab called 'Long Term Fuel Trims'. I would reset this so they all go back to zero. If you have not yet applied the new correction to the MAF Calibration Table B5001, then you can do a single correction of ~ 3% to your entire MAF Table. We need to eliminate the positive LTFT contribution.

Perhaps after I scan your Tune & Log in greater detail, I can post up an example using your data.

The issue of the VE Table values being somewhat lower is a little odd. The higher you can get your Rpm's, the higher your MAF Frequency should go. Sometimes a 'dirty' MAF will cause the airflow values to be under-reported. Have you ever had your car on the dyno? I would be curious to see how your HP/TQ curve is.

I'll get back to you later..

[Strong05]

I haven't had this car on a dyno before. I can't remember if I cleaned the MAF before either... but I think I did when I installed the SLP lid. I am running a K&N filter though and I know they can cause problems for MAF's, so I'll take a look at it. The car only has 34k miles though and I've only put maybe 8k on the car in the 3 years I've owned it.

I'm assuming you mean to adjust the MAF by a positive 3% across the board? Just want to be sure.

Thanks,
Brad

[joecar]

Brad,

DYNCYLAIR is calcuated by the PCM from the VE table (and MAP and DAT (dynairtmp))... it was dropping with RPM below peak torque instead of rising to peak torque (and then dropping after that)... now with this new VE dyncylair does not drop until after peak torque, but it is lower than previously.

With long tube headers your VE table should have gone up a little in all places... something is wrong here, either some tables are wrong, or engine is not able to breathe properly... yet your LTFTBEN's are close to 1.00...!?

Some other things are not quite right:
- LTFTBEN is close to 1.00 but wideband AFR deviates from commanded AFR;
- IFR table is for 26 lb/hr injectors, but your 2002 should have 28.8 lb/hr injectors.
- MAF airflow (g/s) should be a little higher... 6000 rpm at WOT I was expecting to see 275 g/s, your log shows around 245 g/s.

Maybe you should measure pressure at the fuel rail (snap throttle open and observe any deviations).

[joecar]

Shawn, what do you think, do you see any inconsistencies...?

Edit: I saw your reply after I posted these 2 posts... I see you mention dirty MAF.

[WeathermanShawn]

That is correct on the MAF (+3%). Positive adjustment to the MAF will decrease the LTFTBEN's. The correct way is to apply the entire B5001 log LTFTBEN values, so this is a shortcut. Even though your LTFT values are close to zero, sometimes you have to force the entire LTFT average to ~ -2 - 3% to get rid of any positive LTFT's.

Joecar I am glad you caught that on the Injector Value. There does seem to be something wrong... I wonder if the OP goes back to the stock injectors if that might make the LTFTBEN's go more positive..which will drive up his CALC. VE Values..

Brad, I assume stock cam?