thebucky84

iTrader: (4)

Alright, i've finally reached the point of lol. I've been trying to learn and tune my car for several months now (car and mods listed below). I have a base tune on it now so its safe to drive. My issue is that every time i go for a drive (30+ min) and take a log all my LTFT and STFT's are around -60 for both. Now i've read all the threads on how to multiply by % and junk. Well nothing has worked. Every time i do so i look at the 3D graph and it looks crazy, all spikey looking. I wouldnt say i'm a newb at tuning but there is a lot i probably dont know. If anyone can lead me in the right direction that would be great!

When i go out for logs i have MAF failed at 0hz, i have my high octane table copied to my low octane, turned off the light to p0101, p0102, and P0103, and I have my PE Enable TPS set at 100 across the board. Tuning for MAF Failure here.

2007 Cobalt SS/SC
Mods:
TVS Harrop SC with 2.8 pulley
80lb Flowmatched Injectors
LS4 TB
TB Spacer
3in Intake
Intake/Supercharger Spacer
Wideband (not on hpt)
Cat back exhaust
Heat Exchanger


SOME ONE PLEASE HELP! lol

Thank you,
Shawn

Chevycobaltss3

iTrader: (2)

First off it sound like u have corrupt data making the logs read in the 60s do not turn off the maf codes unless u just doable the mil light because u have to have the code to enable ve 100% ure car shoulde be reading like 15 and below not even close to 60 I seen this a few times and it was corrupt files in the scan table so I made a new scan table and good to go maybe that helped a little

Chevycobaltss3

iTrader: (2)

Send a log to Cali_motocrosser@yahoo.com I'll look at ure log

thebucky84

iTrader: (4)

You're talking about making new histograms for the STFT and LTFT right? and i have only disabled the light for the maf not the code itself

I don't have any logs saved at the moment, but in a little bit i'm going to go out and do a log. I will send it to you when i'm done! Thank you!


thanks for the quick responses guys!

Chevycobaltss3

iTrader: (2)

u need to basically make a whole new histo, stft ltft go from the begining...........ill send u one when you send me an email.

thebucky84

iTrader: (4)

im sending the email now.. i made new histos and it seemed to work.

Chevycobaltss3

iTrader: (2)

ok kool i will look when i get home.

skatin_boarding

I recommend learning how to tune your maf before you hop into ve tuning. Its the same concept just only 1 row of numbers.

Are you using an average of both stft and ltft to tune your fuel trims? You are making the changes in the ve table right (no offense just checking)? Remember to enable your maf after you max out your ve table and tune that so you dont loose fuel.

Im going to guess your not logging your fuel trim perimeters when you scan the vehicle. Sounds like chevycobaltss3 has got you in the right direction. I just wanted to add my thoughts.

Chevycobaltss3

iTrader: (2)

whgen doing a maf table i would rather him do his ve first, because say that his maf is messing up while tuning the maf, his readings wont be correct, and if they are not correct then he would automatically go to the ve. I always tune ve then maf, either or is fine, i just like to tune the ve first so i know if anything happens to the maf while tuning or almost done with tuning he would be ok. but to each there own, ive seen it done before, the only reason i would evejn attempt doing maf first is if your ve is off by alot. and wont run right. but in most cases u wont be

csementuh

iTrader: (18)

MAF only tune will solve your problems and make you happy...

Once you get the tune settled, you can go back and play with the VE if you want.

People making big power never bothered to VE tune. Bryan (Area47) said he drew a set of ******* in his VE table on time and the car ran just as good...

Chevycobaltss3

iTrader: (2)

correct sir, but if the maf fails wut now, look in the hp tuner forums and you will see when area 47 went back on his remark about tuning the ve when the high senior tuners showed him our cars use both maf and ve since we run in stady state and we got wot we would change from maf to ve since the factor of steady state.

csementuh

iTrader: (18)

Links..?

I believe you got that backwards. When WOT in PE mode the car should be completely MAF only, not MAF to VE, but VE to MAF. Stock 'Dynamic Airflow' is somewhere up until 4-5K RPMs then MAF should take over fully. Most people lower that or in the case of MAF only lower the Dynamic Airflow setting to below idle so that VE is never really used.

VE works better for small loads on the engine as MAF is exponential and can't measure small airloads well, but MAF is much much more accurate at higher airflow and resolutions.

You're right in saying that the VE is still used a bit, but it is only in transitional fueling during cruising, DFCO, and throttle tip-in I believe. I also believe that the earlier 16 bit PCM's up until 06' used VE a lot more for fueling, where the 07' 32 bit PCM did not really use the VE data for much of anything when MAF only.

Most people would recommend tuning the VE up until about 3200RPMs or so to help smooth the bottom end and crusing, but after that it would be MAF all the way. Once you go WOT, open loop kicks in, and the car should only be running only off of the MAF sensor's airflow combined with the last STFT value added in. Me I'll take my chances and run MAF only. If the MAF so happens to fail at a high RPM, high load, high speed WOT run, so be it.

If you have any other information, I'd love to learn. What I said above is simply things I've picked up from countless hours of reading and playing around with stuff.

skatin_boarding

I tuned my maf first the got my ve reasonable in cruising sections just in case of maf failure.

Chevycobaltss3

iTrader: (2)

if you have maf set at wot, it will then go to the ve at wot. the link is somehwere in hptuners i4 tuning. ill try to get the link, i know what i am talking baout, you can ask any tuner that know how to tune at wot the map is converted to the ve. i have my dynamic set at 400/350. and my mafe skews at wot or dont read.

Chevycobaltss3

iTrader: (2)

i think it is either in the schafer injector settings or somthing, because i know there was a few of people arguing that it dont matter if you ony run on maf, but the car runs off both. and the conclusion was we need the ve and need to tune the ve so we can get correct afrs if the maf fails.. o and he prob drew ***** (****) in the middle map and not wot part.

csementuh

iTrader: (18)

I'm sorry, but clearly there is a disconnect here... The VE table only goes up to 6800RPM and 215KPA.



(Please ignore my terrible VE table as I don't use it)

Most people spin higher than 6800
215KPA - 100KPA Atmospheric Pressure = 115KPA = ~17PSI Boost

The VE table CANNOT fuel above 6800RPM or ~17PSI of boost. So yes, sure, if you have a milder setup, then by all means tune the VE all of the way up. But for anybody that revs higher or runs more boost the MAF needs used above this value.

You can 'trick' the VE into working above those values but it simply repeats the values from the last cells of the tables, but that is guesswork at best, and not a good solution. This brings us into why a boost referenced fuel regulator setup is needed above that as well... But that's a whole other topic.

Sorry to threadjack op, but some confusion needed cleared up.

Redo your scans and go about your merry way tuning... Just remember to dial your MAF in all the way up so you have proper top end fueling...

Chevycobaltss3

iTrader: (2)

yes sir you are correct there, but understand this, i said, steady state, when you go open throttle not even wot your car will go to ve because of the split second change, wot it will go to ve, wutever the last cell is in the ve it will hit it and remember it and go from there, the maf is not used under a steady state change to wot. im not stupid im not lieing, i know what im talking about. ive tuned many cobalts, vettes, silverados, alot of crap, but when you have a vehicle that has steady state, yur car will change to either or, wutever is suitable. you can make your car ignore the maf, but im unsure you can make it ignore the ve. . like when you tune your maf, tell me why you should not got wot pulls??? Because itll skew the map right, do you think you can get to the higher hertz by just going part throttle, prob not, you can make your maf map to compenste by afr error per maf herts. and go from there but you have to dial it in that way, our cars will skew get false reading, it does go to the ve for wot pulls, it might go from on to the other but it does change.

csementuh

iTrader: (18)

Huh? I'm sorry but your post hurts my head. Please take the time to seperate your thoughts better if you would like it to be properly understood. Please also use correct terminology.

'Steady State' has no meaning to me. I just looked at both of Greg Banish's books, and there is no mention of this type of PCM parameters.

Open Throttle = WOT, WOT = Open Throttle? Not sure what your trying to differentiate here. If the throttle is 'open' then the car is 'floored'. Example Throttle Position Sensor = 100% (Actually 88% on the Cobalt PCMs).

There is also the difference of PE vs WOT, in which PE can be enabled prior to WOT in HP Tuners. Is this what you are speaking of? If so this is open loop operation and it should use the MAF.

If what you are trying to say is that the PCM uses the VE table for throttle transitions, deceleration, and 'sanity checks' to make sure the MAF is reading properly, then that is a correct statement (which I said and agreed with in an earlier post).

Ohh and with 'Dynamic Airflow' setting set at a low RPM, the VE table should barely be used. The 'Dynamic Airflow' refers to the blending of the VE and MAF readings to properly fuel the engine. If you set the threshold below below idle, the VE should only really get used if the MAF totally fails and reads to high off the charts. You can keep the MAF resolution proper by sizing your intake tube to the airflow application and scaling it properly.

Please explain yourself if you wish to be understood using examples from the Cobalt LSJ tune file tables, parameters, etc. Also please use referenced names and terminology from EFI tuning literature. Does anyone else get what you're trying to say? No disrespect, but I'm not following you as this does not coincide with EFI theory or tuning parameters I have ever seen.

Chevycobaltss3

iTrader: (2)

Nothing against you bro, efi terms, i totally understand, i use terminology from what i just speak out. When you go wot, say what ever percent it is, that speratic punch in the throttle you will go into ve mode and then back to maf., you are correct about the whole ve wutever, i understand i really am not stupid. if you want to make me look stupid, you can try. But what im trying to get at is he needs to tune ve before maf unless his ve is out bad. tuning the maf in some instances is fine first i jsut dont agree to 100% maf, like i said i have mine set for a 100% maf, but you need to tune the ve because of a speratic change in throttle. will make it go from maf to ve. ask on the forums. read about steady state if you are not understanding, i really do know what i am talking about, and as you do also, but we ar enot agreeing on things, as most people dont. so ill use my way as you will use ures, i have alot of cars tuned by me that will talk great about my work.

csementuh

iTrader: (18)

Nobody ever tried to make you look stupid. I asked for clarification of your point because I found it confusing.

So the basis for everything you said was during a 'sporadic' change of the throttle, the VE is used? Yes. This is correct. I said it in my post #12 which was my first in-depth post on the subject. VE is used during throttle transitions, which means when you stab the throttle it is used. This is very minute though, and the PCM does a sanity check against the VE table to make sure everything is legit. As far as WOT, you made it seem like the VE is NEEDED and USED at WOT. This is not the case.

So in a nutshell, the car can be ran without ever tuning the VE. My car has never had the MAF disabled to VE tune. Only the MAF has ever been touched. It simply probably won't be as smooth as a car that was VE tuned as well. It is simply faster to tune MAF only. I change up my setup too often to worry about perfecting the VE as well.

Chevycobaltss3

iTrader: (2)

Yes sir basically what i meant, sorry, i seem to have a hard time putting what i mean in words lmao, ask any of my local guys here in kentucky on our forums lol. This was exactlly what i was trying to say also, i jsut seem to feelbetter about my tune with the ve tuned and maf. i dunno, im just safe i guess.

thanks for the clearification.

csementuh

iTrader: (18)

No thank you for the clarification lol. I guess I'll have to stop being lazy and dial in my VE one of these days once I stick with a setup I like.

Good luck to the OP!

Chevycobaltss3

iTrader: (2)

I think I tune my car about twice a week or more

thebucky84

iTrader: (4)

soo can anyone help me out here haha.. chevycobaltss3 you get a chance to look at my logs and tune?

Chevycobaltss3

iTrader: (2)

sorRry bro I just got done tuning a cobalt tc I'll look at it here in about 30 mins