Weird Commanded AFR issue

[schnellTTZ06]

This is on my '03 Z06 with the 2bar tune and .5bar boost. I have been getting drastic shifts in my afr under boost (between cells that had similar settings in the fuel cells) that didnt make sense. So I decided to start logging commanded afr to see what it was actually commanding. Turns out it has been commanding 13.93 and some other lean values even though it should be commanding 11.76 all throughout the boosted regions above 120 kpa. It seems to me that it is bouncing back and forth between the PE and the BE table but it should be using the richer of the two which is the BE table. Normally I have my LTFTs disabled but I turned them back on to help out with fuel mileage and it does show LTFTs when it is under BE. I know Im getting a bunch of KR too but Im assuming that its related to the less than subtle afr shifts and some lean conditions. I would appreciate any thoughts.

[NYLS1346]

i just had the same issue the other day but havent seen it since, in an 02 ss with a turbo and boost enrichment set to 105kpa to turn on, and up until 125kpa the computer was commanding 14.00 when i have BE set to command 12.00af

[VYSSLS1]

set the PE to 1.25 as well and the problems will go away...

[Frost]

Boost enrich is too slow to rely on for a twin turbo setup. That log is slam full of knock under full load/boost too... Why don't you just run less timing until you get this figured out? There are also places in that log where the AFR is 12.3 to12.7:1 at 9.5psi (165kPa) with knock as well. I don't want to sound like a jerk but slow down before something gets hurt.

Lower your timing under heavy throttle. Just go ahead and pull 3 out of everything at 0.54 and numerically greater.

You are commanding almost 14 in your PE table, that's where the high 13 is coming from. You need to get the fuel setup to come in quicker. There are places that the car sits in CL on the edge of PE and then you push and get boost faster than fueling can update.

I generally setup the PE with rough fueling... starting near N/A values down low. If you look at your logs, you are on the gate by 3600, and making good boost by 3200, so let's put the fueling in there in PE. Also, you can make boost at less TPS than you are set for PE, but we always have to get PE in FIRST. I set it up in your file so that PE is MAP dependent so you get fueling according to load as needed. This will ensure that you will always get PE before BE and that PE is rich enough to cover what could-be as far as boost is concerned.

Use compare to you r last file to see exactly what all I did.

[schnellTTZ06]

Thanks for the good info. Im at work so I cant check the tune. My understanding from the help files was that it would go into the richer of the two between the PE and BE and I did set the PE leaner to make sure it went into the BE tables. I kinda figured the PE tables were irrelevent with the 2 bar anyway, guess I was wrong. I did change the PE tables to almost match the BE tables, making them 1% leaner to still get it to run off the BE table and that seemed to work. I cant upload the log files now but strangley it would still sometimes use the PE table versus the BE table even under full boost and WOT. But this got rid of almost all the KR, I think Im just running a bit too much timeing and should reduce it as you said.

Dont worry, dont think you were being a jerk, I appreciate the info. I know I run this car on the edge but its taken every bit of punishment that Ive thrown at it - been running it hard since '05 and over 30k mostly high speed Autobahn miles with the turbos. I will be tearing it apart this fall and forging everything so I guess I will see what damage there is from all the KR.

[NYLS1346]

im still having an issue with the boost enrichment on my car, it seems to go into be at wot and above about 130kpa but i have it aet to go into be at anything over 105kpa and call for 12.0a/f and then it tapers off to 11.5..

but in my log today i was at 120 kpa and 3500 and it was commanding 14.6a/f

its kinda annoying that i cant figure this out lol, is there an issue with the BE feature, i would really like this feature to work properly as it would make life alot easier

thanks

[Bill@HPTuners]

im still having an issue with the boost enrichment on my car, it seems to go into be at wot and above about 130kpa but i have it aet to go into be at anything over 105kpa and call for 12.0a/f and then it tapers off to 11.5..

but in my log today i was at 120 kpa and 3500 and it was commanding 14.6a/f

its kinda annoying that i cant figure this out lol, is there an issue with the BE feature, i would really like this feature to work properly as it would make life alot easier

thanks

Post a log of the issue & the current file in the vehicle.

[NYLS1346]

here it is

[NYLS1346]

and the tune

[NYLS1346]

frame 2319 is an example if you look at the commanded a/f

[Bill@HPTuners]

.hpt file is tunerlocked and not able to open.

[Frost]

im still having an issue with the boost enrichment on my car, it seems to go into be at wot and above about 130kpa but i have it aet to go into be at anything over 105kpa and call for 12.0a/f and then it tapers off to 11.5..

but in my log today i was at 120 kpa and 3500 and it was commanding 14.6a/f

its kinda annoying that i cant figure this out lol, is there an issue with the BE feature, i would really like this feature to work properly as it would make life alot easier

thanks

I thought there was a glitch, and there kind-of is... if PE isn't met first, trimming will not stop when BE is active.

To make sure BE works, PE MUST MUST MUST be active first. To do this, set the PE MAP enable to something like 76-83kPa and set the cold TPS PE trigger % very low, like 14-15%. The idea here is to trigger PE off of MAP rather than TPS, which is the OEM arrangement.

[AkSSS]

I thought there was a glitch, and there kind-of is... if PE isn't met first, trimming will not stop when BE is active.

To make sure BE works, PE MUST MUST MUST be active first. To do this, set the PE MAP enable to something like 76-83kPa and set the cold TPS PE trigger % very low, like 14-15%. The idea here is to trigger PE off of MAP rather than TPS, which is the OEM arrangement.

Just trying to understand the setup here. The cold tps tigger will be low. What do you do with the hot setting? Set it up to not go into hot mode, or do you have the hot tps pe trigger to be around 50%? I'm pretty new to all this. Just trying to do this on my own 2bar gen III.
Thanks

[Frost]

Set it the same or set the enable temp to 284.

[robbyredneck]

hey op did you figure this out? i am having the same situation. i am definately trying triggering pe off map.thanks frost.

[DSteck]

Just set PE enable MAP to 85 and be done. I do this on forced induction settle and run really low TPS enable, and it works out perfect every time. My 105kPa cell is always the same as the PE ratio, and I'm typically at 11.4 or so by 7psi. You can play with the TPS values down low since some turbos will enter boost very easy, and you don't always need to dump fuel at 1500rpm and 90kPa.