VVE Tuning question

[2012silver224]

Newbie here trying to figure out VVE tuning...I followed the tutorial and set up my histogram for the LTFT+STFT [math].Question is now at this point do i put the truck into SD log and copy and paste and once its dialed i copy the main VVE table to the rest? If im missing a step please let me know... Also i dont have a wideband.. Money is tight right now and cant afford one just yet

[5FDP]

Yes, you'd put it into speed density for tuning the VVE.

Set the MAF fail high to 2hz, low fail to 1hz, then your 3 MAF DTC's to fail on first error. That will put it into speed density right away. You can also disable the COT and DFCO for the time being to prevent them from maybe skewing data.

In the VVE editor you'd make the changes to both the manifold switch open and closed tables. You don't have to do the DoD switched tables.

[2012silver224]

ok perfect.. thank you

[mowton]

Make sure you are tuning and updating the Manifold Open table. The software defaults to the Manifold Closed table which will screw you up big time. This may be overstating the obvious but make sure you calculate the coefficents as well....then if you like, you can copy those values to the other 3 tables (generate coefficients for each) though that really isn't necessary.

Ed M

[2012silver224]

so when i paste to VVE i paste special -add, then calculate correct? also should i disable PE completely?

[mowton]

No......to all

You will Copy Mult % or Copy Mult % Half if you only want to use half your error value (used as you get close to zero error to prevent over/undershoot).

Never Ever disable the PE!!!!! Your error data is derived from your commanded Lam/AFR and WB readings so your error will always be valid. Why would you want to disable the PE protection while logging. The Commanded LAM AFR will be made up of the Stoich plus PE values when active. The Wideband will report the Lam/AFR of the exhaust regardless so only the MA/VE, which you are tuning, will be responsible for the error and will be corrected accordingly.

Caution also that you have disabled any other possible enrichment features like Cat Over Temp, as this enrichment is added to the fueling but not represented in the Commanded Lam/AFR ......you will be leaning out for a false rich condition leaving you final MAF/VE very lean.

Another disclaimer is if you are logging in closed loop and using a WB to report Lam/AFR when in PE separately, watch the trims just prior to entering PE (open Loop/Acceleration). If they are lean, the PCM will also add this additional fueling but again, not report it through the Commanded Lam/AFR....more richness we don't know about ..... that is one of the main reasons to tune solely in Open Loop with a wideband.

Ed M

[schpenxel]

Why would you want to disable the PE protection while logging.

Someone out there keeps telling people to do this so that they can use fuel trims to tune WOT without a wideband. It makes me want to bang my head against a wall. This is the 3rd or 4th time I've seen it in the last month or so.

I'm not 100% sure who it is so I won't spit out any names, but I have a suspicion it's the same person that recommended setting the IAT multiplier table to 2 or higher when wanting to run larger injectors than the factory flow rates limit allow.

[2012silver224]

im sorry guys like i said im totally new to this... I do not have a wide band and cant afford one at this time... Ive just been reading through the forums trying to figure out narrowband tuning till i can get to a shop

[mclarkesr]

Caution also that you have disabled any other possible enrichment features like Cat Over Temp, as this enrichment is added to the fueling but not represented in the Commanded Lam/AFR ......you will be leaning out for a false rich condition leaving you final MAF/VE very lean.

Ed M

Do you want to leave the COT off even if you have no cats ?

[mowton]

Do you want to leave the COT off even if you have no cats ?

If you have Hi flow or no cats then you would leave all the Cat stuff disabled after tuning as well. If not (OEM Cats) then I would recommend re-enabling them

Ed M

[mowton]

Someone out there keeps telling people to do this so that they can use fuel trims to tune WOT without a wideband. It makes me want to bang my head against a wall. This is the 3rd or 4th time I've seen it in the last month or so.

I'm not 100% sure who it is so I won't spit out any names, but I have a suspicion it's the same person that recommended setting the IAT multiplier table to 2 or higher when wanting to run larger injectors than the factory flow rates limit allow.

So the only reason I ever came up with is they don't want to disable the trims (PE=Open Loop/Acceleration and resets trims to zero) and use them higher up he load band for those that don't have widebands....but again, if you were suppose to go into PE at that point then tuning to stoich would just result in lean operation anyways...so I see no point to it...

Ed M

[2012silver224]

ok so stupid question i just realized I may have screwed up my logging,, I set my Maf to fail, set the DTC to error on first, Disabled COT, and DFCO... Am I still suppose to copy High Octane to Low Octane? If so its back to square one!

[schpenxel]

Why would you be back to square one? We're talking about air/fuel here, not spark

Regardless, on gen 4's you don't have to copy high octane over to low anymore unless you just want to

[Jggregory99]

Someone out there keeps telling people to do this so that they can use fuel trims to tune WOT without a wideband. It makes me want to bang my head against a wall. This is the 3rd or 4th time I've seen it in the last month or so.

I'm not 100% sure who it is so I won't spit out any names, but I have a suspicion it's the same person that recommended setting the IAT multiplier table to 2 or higher when wanting to run larger injectors than the factory flow rates limit allow.

Believe it or not, I have several books from several "Reputable" sources.... Again...No Names... That advocate, and recommend turning off PE and using a slow acceleration approach of less then 5-10% throttle movement to tune VE and MAF up to 4000RPM. Not saying it's the right thing to do, but honestly, until I started dealing with ED, this was what I was taught, so it WAS the way I tuned... Some people don't investigate different tuning methods, or just blindly trust that the person teaching them is as good as they say.. My motivations were a little different, as I wanted to try and make some extra $ doing this in my retirement, so I learn from everyone I can.. You, Ed, DP, etc Bottom line is... until someone teaches them a better way... People starting out can only go by what they are taught, from the companies willing to teach it, or reading the available books on tuning... JMHO so, take it for what it's worth...

[schpenxel]

Very true.. I guess it "can" work on basic NA applications.. GM gets away with it on trucks, but I still say it's a bad idea

[2012silver224]

Can someone look at my tune real quick and let me know if im truly in speed density. I have the check engine light on like im suppose to, I just cant get it to log anything other then 10kpa .. While I think my logs are getting better im still showing lean at idle... For some reason I cant post my log but will keep trying... Thanks again

[schpenxel]

Sometimes logs get too big to post. Try a shorter one and try posting that. I can't look at the tune right now but will try later if you can post a log too.

[mowton]

Yes looks right...if not sure...

1) do you have a check engine light? If No, then most likely not, if yes, check the DTC's and see what code...if MAF fail code then yes. Check the DTC's regardless and report.

2) When all else fails, zero the MAF table and see if the vehicle will take any pedal...if it can, then you are not....may be a bit tougher to start but pedal alittle if you have to or leave the maf to about 3000 hz and zero the rest.

Ed M

[2012silver224]

ok perfect thank you... Figured out I was a dumb@$$ I was only seeing 10kpa cause i did not have the PID for manifold on the channels... Added that now i have full readings... If I need to minus some fuel trims from VVE can I paste special subtract or no?

[schpenxel]

paste special %