Looking for some input

[Sierra09]

I am looking for some more experienced tuner to look over my tune. I have my VVe Table decent, could maybe go for another trip and multiply 1/2 percent again. I have not went any Farther Than tuning VE table, My question is my stft are pretty close to 0 but then my ltft are way out to lunch -12 - -20 and not changing? i am tuning via AEM wideband.
Just did a short drive tonight and scanned after driving to town few times, pretty well the same temp as the weekend.

My second Question is i am getting a drop out of spark while just cruising down the road, But no KR?
Any Help would be appreciated
Thanks


Attachment 59743Attachment 59745

[Sierra09]

212-218 comp cam
TSP Headers Catless Y-pipe
Minor ported heads

[gmorris]

Looking at your first log it appears that you are just running super rich...I wouldn't say your vve is decent lol. When making changes to the vve are you making sure to make the same changes to all 4 vve maps? manifold open and closed? I chased my tail for a while by only changing the first one which had no effect? The first log was with you maf failed correct?

[JBZ]

im seeing some KR in there, not when the spark drops. some of the drops look like tq management during a shift. but I do also see some erroneous drops in there, regarding those timing adv drops while steady state cruising I have read that it could be ac torque reduction tables (torque management/AC torque/torque reduction) and that is fairly normal, it could be every time your ac compressor kicks in. I don't know if that is true but have read that on another forum. others may be able to chime in with more knowledge.

[Sierra09]

Alright, so if I continue on with the VVE tuning to get into the + -4, the spark drop out was not there until I started tuning VVE. Wanted to double check with someone who might know. I was just curious about why my wideband is in the 4-6 range and my ltft are -12 -20?
Yes, I am going in closed switch special multiply smooth by hand then copying pasting in open switch?
MAF failed

[Aaron407]

Your LTFTs are trying to correct for the VVE being a fair bit out. When you make corrections, you should be using primarily the LTFTs, STFTs + LTFTs, or STFTs only with LTFTs turned off if you're impatient. Regardless, your VVE needs work to correct for the fuel trims. Also, if you make significant changes, remember to reset your fuel trims before logging so your STFTs don't fight against your LTFTs.

Lastly, it's probably not worth tuning your timing until you have your VVE dialed in. Without that, your dynamic airflow calculations are going to be off, and your calculated cylinder airmass isn't going to be correct. As a result, you'll be pulling from the wrong cells in your timing table.

[Sierra09]

Alright so what your saying is don't worry about KR until I am completely down tuning VVE table.
I am tuning the table via wide band error resetting ltft every time.

[JBZ]

I would be concerned about that KR if it were me, although Aaron407 may be right about cyl airmass changing but I still would modify those spark cells and the surrounding down a bit until you get your VVE table taken care of, then you can properly tune spark...just my opinion though.

[gmorris]

Are you sure you are forcing open loop when tuning with the wideband? You should see zero lt and st corrections if you are. I don't see how you could still be at +/- 20% LTFT's if you have done a few passes of correction with the wideband and no fuel corrections being done by the ecu.

Also, make sure your error graph axis' are the same as you vve table so you are correcting the proper cells when pasting and multiplying. That can really put you in a tailspin if not correct...something seems off if you are still getting that large of fuel correction after tuning vve.

[Sierra09]

That's what I'm not understanding, I get the MAF fail dtc code as soon as I start the truck. I failed it by changing the MAF freq14500 to 0 and setting codes p0101 102 103 to first.
This might be a dumb question, but trying to learn as much as possible. When you fail the MAF are you not trying to tune closed loop in regardes to 02 sensors?

[gmorris]

If I understand your question correctly, no. If you keep your 02 sensors active (closed loop) the car will be correcting your air fuel ratio so you will get very little error on your wideband...it's already been corrected by the fuel trims. In that case you can use the LTFT + STFT error function to tune the vve under part throttle conditions but not the wideband. The other option is to force open loop with the vcm controls and just use the wideband if you trust it. Then use the wideband error graph to paste and multiply the vve table making sure to modify all 4 just like you would with the LTFT + STFT. Forcing open loop eliminates the ecm fuel corrections so you get the true AFR error on your wideband.

So basically i you use closed loop tune with fuel trims, if you use open loop tune with the wideband. Otherwise you will get nowhere.

Please clarify how exactly you have been tuning the vve so far...were you using wideband data with closed loop enabled? If so that explains the issue.

[Sierra09]

Yes that's exactly how I was doing it just disabled MAF and was using wide band Error over command. So I should be using ltft+stft math vs map vs rpm for part throttle up to 4000? In closed loop? And then wideband error command for wide open throttle? I would like to keep both open and closed loop active as this is my dd
I was following a write up online but I guess it was incorrect. If you know of a good write up for e38 could you past here or explain further how to do this properly. Dosnt have to be dumbed down
Thanks

[JBZ]

I think what gmorris (please correct me if im wrong) is trying to say is you can tune in either open or closed loop. closed loop tuning for part throttle and normal driving are accomplished with fuel trims via your O2's. open loop tuning is done with your WB. if you plan to look at both your WB for error and fuel trims (which is what is sounds like your doing) you need to add fuel trims learn ON/OFF in your channels list so you know when to apply what. you would use your fuel trims for the cells that the fuel trims are learning but once you go WOT or DFCO they wont learn anymore so you should use your WB error for this.

it seem a lot easier to just put the car into open loop while your logging (via the scanner) and tune with only your WB. you can turn it off (open loop that is) once your done logging, go back to closed loop or just turn the car off. it will default back to cl next time you drive unless you have changed that in your tune. just because your tuning in open loop does not mean that the changes applied will only affect open loop. it just makes it easier to track commanded vs actual. if the trims are on it makes it harder to use WB error because the trims are correcting the fueling, but in open loop they are not so you can get a better view of what the engine does without corrections.

[Sierra09]

Okay so I can tune my CL via ltft+stft math vs map vs rpm to dial in my VE table up to 3500-4000? Or I can turn off CL and tune the whole table using wideband error vs command? Or just up to 3500-4000, the MAF takes over after that bc of PE and has a better reading of air flow correct? So in other words I was incorrect when trying to tune with fuel trims in closed loop and using wideband

[schpenxel]

You can't tune with a wideband while in closed loop. Fuel trims are already making the corrections you need.. so they aren't showing on the WB anymore because they are already being corrected for.

Use LTFT+STFT math parameter for closed loop tuning.

You could do open loop w/WB but I would do closed loop w/Fuel trims instead. Some things like evap purge don't happen in open loop which will make things change a bit once you go back into closed loop.

[Aaron407]

I would be concerned about that KR if it were me, although Aaron407 may be right about cyl airmass changing but I still would modify those spark cells and the surrounding down a bit until you get your VVE table taken care of, then you can properly tune spark...just my opinion though.

I haven't looked at the log, but, if there's substantial KR (e.g., 4+ degrees), it would probably be best to do a bit of a blanket reduction of that general timing table area to keep things somewhat safe while dialing in the VVE. I just wouldn't tune for timing increases or minor KR reductions until after the airflows are correct since it might not be referencing the same cells later on when the cylinder airmass changes for a given actual airflow. If the VVE table is significantly off, especially low in some areas (e.g., it was very low with my G8 GT when in boost), it can command very low fuel via unrealistically low dynamic airflow values and command very high timing, which can be a really bad mix. One thing that I did to help with this before tuning in VE only was to dial in my MAF table, then log both VE airflow and MAF airflows on a histogram based on MAP and RPM (same as the VVE table). If there are big differences in some areas (e.g., VE airflow half of what the tuned MAF airflow is in PE where fuel trims won't be recorded), you could account for a large portion of that difference in the VVE before running VE only to tune it.

[Sierra09]

Hey guys thanks a lot for the help i got it all figured out now. This is a big learning curve and appreciate your guys help, it is uncomparable to and old school . give me a timing light and a carburetor and were golden! Now i have be searching and searching on finding a good histogram set up for idle tuning. i have been reading to log ltit+stit= special paste add = correction? would this be right? If lead in the right direction ill figure it out.
Thanks again for anyone who helps

[BigMike42]

Hey guys thanks a lot for the help i got it all figured out now. This is a big learning curve and appreciate your guys help, it is uncomparable to and old school . give me a timing light and a carburetor and were golden! Now i have be searching and searching on finding a good histogram set up for idle tuning. i have been reading to log ltit+stit= special paste add = correction? would this be right? If lead in the right direction ill figure it out.
Thanks again for anyone who helps

No that's for the Gen3 which is much simpler than Gen4. I just made an idle guide (it will continue to evolve) about gen 4s on the main page. I set up the first step much like how you would dial in an old carbed muscle car, with locked throttle and timing.

Getting the adaptives right is the bitchy part.

[Sierra09]

Could someone just clear this up for me. In order to tune MAF with wideband i set MAF hertz back to stock, Disable DFCO, Disable LTFT Disable Closed loop in order tune Open loop. set dynamic airflow enable to 1. is there anything else i need to do and can i tune entire freq table that i can hit in this set up? Just want to make sure i am not wasting time again.
Thanks

[schpenxel]

Disable DFCO, disable CFCO if manual. Set dynamic airflow high RPM disable to 100, re-enable to 50. This makes it use MAF only, not SD.

Set to open loop, disabling STFT and LTFT's will do that

Compare actual AFR or lambda vs. commanded AFR or lambda and tune MAF to your hearts desire

I'd personally just leave it in closed loop and tune the bottom chunk of the MAF curve with fuel trims though.