The tune on my 99 is driving me crazy... I've tuned 30+ cars and never had this issue...

I can force it into open loop with the scan tool (EFI Live), and tune the VE table to exactly the WOT AFR that I want.

Then go back into closed loop and verify that even with the maf in play, that I still get the desired WOT AFR. I do, it stays 12.8:1 for example either.


WAIT A FEW DAYS.

and on a WOT pull the bitch will be 11.4......

I have tried everything I know of.. I have tuned the VE tables with AUTO VE. Fuel trims are within +- 5%, MAF frequency tables appear to be right on target. ALL modifiers such as IAT, ECT, CAT protection etc are zeroed out or disable.

What in the hell is going on with it? What should I check?

I'm going to migrate this tune over to a 2002 OS and see what happens. I would just like to figure it out for future reference tho.

 

What are the LTFT when it happends? Some people disable LTFT to avoid them adding to PE

 

Post some log files.

 

LTs are within 5% throughout the RPM range.

 

I wont be able to get any for a couple weeks.

I can post my tune though. I migrated it last night but I can post the old one.

 

Yes, post the old one.

 

Here it is

 

If they are positive then they could be adding 5% on top of your commanded

 

You will never get them perfectly zero.... that's not how it works.

Besides its adding way more than 5%...

 

If youre going WOT, why are the LTFT's doing anything? Shouldnt you be in open loop?

 

If you are lean, and LTFTs are positive, the % they are at when you go into open loop locks in and adds during open loop as well...

 

You tuned those VE tables? They are not even the same...

You need to get logs to see what it is commanding, what the wideband is reading, and what fuel trims are doing when you go into PE...

 

What do you mean they're "not even the same"? Yes I tuned them with auto VE and got the fuel trims dead on...

 

What I mean is that when you tune VE tables, you should be in speed density - and when you are in speed density, a 99 runs off of the backup VE table... You have to tune the backup VE and the VE tables - your backup VE table and your main VE table should end up the same - yours are way different from each other... The way your tables are, when you switch from speed density back to the MAF, your fueling will be drastically different...

You might wanna go back and read the autoVE tutorial again... it discusses the backup VE table on page 4...

 

+1 what BLK02WS6 said: the Main VE and Backup VE tables should be made the same (at their common row/col cells).

Also:

Main VE table looks wrong, it has a big valley, and a sharp ledge, those are not right.

MAF table has a small discontinuity at 8500 Hz, I'm wondering what this is.

HI and LO spark tables are identical; MAF is enabled, so LO table should be made lower to provide some longer term spark learn (altho KR can just handle it ok in the short term).


Not related to question:
D0701,2,3 can be increased some, you can eliminate the flat part (start sloping up immediately); you may want to tailor this according to how low throttle shifts feel on road test; but do increase the higher part of the curves a little (say 15%-20%).

 

I tuned the backup VE table as well using Auto VE. It should have been the same. Maybe I forgot to copy it over and that's what has been causing me issues. I will work on that.

Will be a non issue once I update to the 2002 OS.

Thanks for the help

 

Main VE works for me. I can put it in SD mode and car runs like a champ. Like I said it was tuned off Auto VE. I didnt spend a lot of time making it pretty but it works.

Also I am at high altitude so I usually never see the tables past 80 kpa. Maybe thats why it looks wierd.

I increased the MAF values above 8500. It's an SLP MAF that I removed the resistor from. I used 02 Z06 base MAF tables and started from there.

I purposely copied the HI / LO spark tables in this tune. When I tune for others I do use lower values in the low octane table so the PCM can blend. I wanted to eliminate any variables on my car though, and I get no knock whatsoever at any load range with those tables.

I will work on the trans pressures. I havent messed with those so I assumed them to be stock. The car could have possibly been tuned before though.

Thanks

 

Main VE table:
pretty has nothing to do with it...
look at the attached pic of your main VE...
at WOT (80-85kPa) when the operating point goes from 2800 to 3200 rpm it falls off that ledge; the sudden drop is an airmass difference of 10% which means the AFR will jump by that amount (if your IFR is correct); then after the drop the VE starts sloping back up (a less sudden difference of 10% going the other way).

 

That's what I did to lean WOT. I reduced the values from 3200 up in the 80 kpa column and above.

Keep in mind I don't see the values 85 kpa and above...

Also the converter flashes to 3600 so any time I'm in throttle cells near or at KPA the RPMS are already past the sharp drop off..

I did this when I was trying to address the WOT fueling discrepancy.

Like I said, not pretty but it works fine in speed density with that VE table.

 

Hmmm... ok I see what you're saying;

if wideband disagrees with commanded fuel then one or more of these are happening:
- VE/MAF are wrong,
- wideband is wrong,
- MAP sensor is wrong,
- air leaks,
- injector leaks,
- fuel rail pressure is wrong,
- other.