I swaped my stock motor for a 408ci last oct, Ive tuned it & also had another guy help with the tune. Since day one Ive never been able to cure the idle problems, when you first start the car it will barely stay running by its self. Then it will jump around from 500rpm to 1500rpm till it warms up completely then it will stay 1000rpm, until you put it in gear then it will die or try to die. Ive meesed & adjusted every table I know to adjust & I just cant seem to get it to run on its on. Ive messed with the RAF table, timing, PE table, VE table, Cranking VE, and the throttle cracker table. Its a real PITA when your trying to go somewhere, or just drive it & it doesnt want to idle or stay running. I can put it in gear after it warms up & then the RPM jump around starts again till it either dies or I give it gas to keep it running. Its getting old quick. Any suggestions?

Now on to the other problem, This happens about every other time I drive it. I can drive 30-40mi or so then park go in or etc come back out start the car, it will start its idle deal for a few mins, then I go to take off & it feels like its running on 3 cylinders. It just bogs down, then acts like its out of gas. I can keep pressing the gas pedal but nothing happens, it will then just die. Turn the key off then back on & its fine. Ive checked all grounds & etc, but this just started recently since Ive been messing with the tune. Ive even put the very first dyno tune back in it & it will do the same thing. Its kinda acts like its loading up then just dieing. Any clues on this? I havent adjusted anything for this due to the fact I have no clue whats causing it. Ive been stumped for the past 2-3 months & Im reaching the breaking point of giving up & swapping back to a stock H/C motor. I do realize that it will never run like stock again, but I know it can get close. The guy that used to help me no longer messes with cars anymore, so Im SOL there. I can email my tune if anyone wants to take a look or make some changes Im game to try a new tune because this one isnt working.

Thanks in advance!

 

I think you probably already changed this but have you logged the Desired Airflow and the actual airflow that the car is getting.

 

sounds like an ignition problem or fueling. Replace the plugs and check the wires and be sure you are getting good fuel pressure too.

 

Yeah check the basics, plugs, wires, vac leak etc as well.
Does it log any codes?
As ZL1Killa says, does desired flow match actual flow at idle?

 

Just swapped out the NGK tr6's for New TR55's, swaped the pulg wired for new MSD's, The fuel pump is a new racetronix PnP system. Ive had the car on the dyno, the A/F ratio was like 12.1-1 on the TNT all the way across the board, its defiantly getting the gas. Its got around 57-58psi at idle. No codes have been thrown, I did get two codes for the 02's ther other day, but it hasnt came back. It was the heater sensor malfunction code. The car hadnt been ran in like 3weeks is why that code came im pretty sure. Ive pulled the intake off numerous times and reinstalled to check for leaks, nothing that I can find. The LTFT's are staying right at +7/+8 at idle & about the same across the chart while driving. So im kindar rulling out the vaccum leak. I can say that I remember all this going on when the stock tb/LS6 intake was on there. So the only changes that hve been made since the dyno is FAST 90 & a NW 90mm TB. The car ran great after the dyno tune I did. But that was with the LS6 intake and stock ported TB. I swapped over and it hasnt ran right since. Ive even put my dyno tune back in, of course it doesnt idle right due to size difference, put it still does the cut off out of the blue problem.

 

Can you send me your updated bin again? I saw about 2-3 things in your old file that might be giving you issues.

One of which was wierd was the file size of your bin... They're like ~460kb instead of 512 like all the others.

 

If you need a hand shoot me a pm and I will give you my email, I will be bored tomorrow night at work and will have some time on my hands lol

 

get em' mike .... LOL


hope you get your problems solved man

 

Thanks for all the offers guys, I really do appreciate all the help I can get right now. I will get the tune to all of you who have PM'd sometime this afternoon.

SMOKIN- Could the file size difference be because they are now HPT files instead of BIN? I thinkg that may be why they are small.

 

I don't believe that would effect the file size, but I could be wrong. If they come straight from your PCM and there's no hex editing going on, I doubt there's anything to be too concerned about.

 

all if my tune files are around ~473-476 or so

are you sure you don't have any vacuum leaks?

 

Some other dudes with fast90's have issues with leaks etc. Not saying thats the case, but if you have the time and inclination you could try the ls6/tb on there again.

 

he has a bigger file because he has more cubic inches

 

HAHA, which that was the case, my file is actually smaller then the normal.

Im pretty sure I dont have anyother vaccum leaks, before when I had one my LTFT's would stay maxed out at 25 so I knew it was leaking somewhere then. But now Ive checked everywhere. & the LTFT's stay pretty low so I wouldnt think theres a vaccum leak.

Id put the LS6/stock TB back on, but Ive sold it already.

 

i wouldnt' worry about re-installing the ls6 and stock TB

as long as you installed all the FAST stuff and TB right then its fine. if you are going to do anything for leaks, i would order new intake seals, and a new TB seal. But i feel that is unnecessary....let the guys try and look at your tune(s) and log(s) and see what they can come up with