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Tuner in Training
running issue swapped 63 chevyll
ok, ive got a 2004 4.8l DBW swaped into a 63 chevy ll.... 3bar sd tune vats disabled.... the car started and ran fine the first couple times I started it. now after I flashed it a few times with different tunes it will start and stall immediately(like a vats issue). BUT if I disconnect the battery for 30mins or so it will fire back up and not have a problem unless I try flashing it again, then it wont start again. any ideas? this is one of the tunes Ive been playing with trying a lot of diff things to make it work. Im leaning towards a vats or actual computer problem more so then anything related to my car like Fuel pressure and such. I am brand new to hp tuners and have spent all day looking through the help files and everything points to the vats.... but I have it disabled and still does it!
thankstrytuneagain1.hpt
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Tuner
Being that you are permimately operating the vehicle in speed density, each time you re flash the VCM, it has to fail the MAF before it will go into speed density mode and read the VE table and run correctly. I have this same "problem" (if you want to call it that) with my supercharged corvette.
Next time you flash the VCM, when you go to start it try to keep it running using the accelerator pedal. Id be willing to bet it will smooth out and then start up fine after that. (Until you flash the VCM again) it's just something you have to deal with each time you flash the VCM.
Last edited by fullthrottle; 09-19-2014 at 03:45 AM.
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Tuner in Training
if you ask me that's BS! heres what im going to try today...
http://www.hptuners.com/forum/showth...r-writing-tune
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Tuner
If it's a maf fail thing which I believe it is in your case there's not anything you can do the maf has to fail before the car will revert to speed density. Once the vcm fails the maf it will work until you reflash the vcm. Why it continues to work is because the vcm saves the P series codes and it knows to revert to speed density or the VE table. When you reflash the vcm, those stored codes get erased so it has to essentially learn to automatically revert to speed density. It's not a big deal really.
The link you posted, the guy is dealing with a MAF sensor actually in operation in the vehicle. Different situation than what you have going on.
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Tuner in Training
how long does it take you to get your car to fire again? it started for me right away... pulled it out running it, drove it around a little bit went to make a change, flashed it, and now it wont start again(starts and stalls immediately) and I see what your saying about getting the the maf code set.... is there anyway to speed that process up or do I have to keep cranking it and hoping it will set the code? wish I could just turn the code on manually.
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Senior Tuner
try this, may help. Still may need to feather throttle on initial start after flash.
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Tuner in Training
^I will try that now... write entire or just cal?
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Senior Tuner
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Tuner in Training
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Tuner
Yeah you can't set the code yourself "persay"
Mine varies. Sometimes it will spit and spudder long enough for the VCM to fail the MAF and then smooth out. Other times it won't stay running long enough for the VCM to fail the MAF hence the need for me to keep it running until it does.
No amount of air flow modeling adjustment you make is going to change the need for the maf to need to fail before the vehicle starts in Speed Density Mode.
I recommend if you can get away with actually running a MAF sensor that you do so. Im assuming you have some sort of forced induction on the car since you have a 3 bar OS. If you can't get away with adding a MAF to the system then it's just the nature of the beast when you are forced to run a speed density only tune. Fortunately you only have to deal with it during the reflashing process.
Gm designed these systems to be a blended MAF and VE calibration as it pertains to air flow models. It's really a great design!!
Last edited by fullthrottle; 09-19-2014 at 02:54 PM.
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Tuner in Training
ya its a turbo 4.8l. its just frustrating because I didn't buy the pro hp tuners 
and have to reflash everytime I want to make a change! im going to eventually kill my battery and starter trying to get it started after a reflash! and now I just had something weird happen.... it will start up run great for 1min and then die. no restart at all. pcm is not turning on the fuel pump or inj. I can turn the pump on in the vcm scanner but the car still wont start! I tell ya, definatly not as simple of a program as im used to and with the issues of the stock pcm, it is driving me insane! I just want to drive my car!
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Tuner in Training
well looks like the pcm was bad! went to the junkyard, picked up a computer, flashed my same tune into it, works great! thanks for the help guys!
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