mine is horrible in and out of throttle in lower rpms. No matter how soft i come back into throttle it bucks. I wish i knew the secret. It was prefect on the first tune hal did for me then it went to crap and he couldn't get it to stop doing that on my second tune. It's been that way for a year and a half and i hate it.

 

Even with the Haltech you could not get it out........Wow.

When I tuned for 440cc's it ran like stock, and their was far less variation in the Cell value in Vac with the 440cc's than with the 600cc's. I don't understand Why?

Also, is it better for the ECU to be on the Side of Adding Fuel or Subtracting Fuel in closed Loop. I know that you want St & LT Trim to be near "0", but what side works better if any?

 

Thanks.....

 

mine would buck if my TB was calibrated exactly right doin teh pedal method then starting immediately after the CEL light goes solid. You did that properly, correct?

 

what are you saying? It would buck when calibrated exactly right?
Can you explain more.....

 

i meant wasn't calibrated correctly....

 

Regarding bucking I'm not on haltech but getting the minimum injector time exactly right makes a big difference in on/off throttle response. And on the heltach you probably have adjustable decel and tip in maps to also mess with. Playing with the min. injector time enough got it to stock feel on the 600's for me.

Regarding closed loop I always make sure it's subtracting on average. Why risk it otherwise.

 

Idle Air Volume Learning, Right?

 

ya, i've done it a few times as well as changed throttle bodies. I'm pretty sure hal did it on the dyno as well. I'll try it again because it can't hurt anything to try.

Mine ran like stock on DW800's. I only started having this problem when i went up to HKS 1000's. I've messed with every parameter in tip in, decel, ect on the haltech.

yes, that's the one he's talking about. For it to work properly there are a ton of things that have to be correct on the car for it to "take". It outlines it all in the manual.

 

As you probably know many larger injectors just don't handle low IDC's well. From what I've seen everyone seems to be flocking to the ID injectors as they flow much more accurately at low IDC.

 

This i do know but there are many out there with 1000 and 1200 cc injectors without the issue.

Charles from CJM runs the exact injectors i do without the problem. I'm pretty sure it's tune related

 

Well got most of the Drivability Issues fix, not perfect but about 95%....

So, To Date this is my Best Street 93 Octane Tune 523/416, up from old of 447/370

I have some Fuel Pressure Fluctuation in Boost above 12psi, I don't like it at all... and I don't know why?

 

stock block right? regardless, those are some good numbers. i'm sure it feels healthy...

 

walbro is maxed.

On a stage 0 return system i ran out of walbro at 451hp. The piping is just too small so nearing higher rpms my pressure would drop. Walbro couldn't supply it. That vortech really eats the crap out of fuel with the added drag. I would say upgrading the fuel lines to get more out of it. That stock 5/16" supply line is very restrictive. If you make an 8an braided line you will have less resistance and then a little more headway with the walbro. After that you might have to go to one of the new 340 or walbro 400 pumps.

That's a huge increase for your tune. No matter if those numbers are accurate or not you still have ~70hp more on the same testing platform so a heck of an increase.

what did you do to get the driveability better?

 

I thought the Walbro might be Maxed....

Well, I quess I just need to Build or Buy a complete RFS.... and a Bigger Pump... or are you saying I'm OK without a Return if I do an -8 Line?

The Car continues to make more and more power.

I just continued playing with the cell values, and then after driving for a while it got a lot better......this is with the SplitSecond.

 

good information here, im for more updates on the rfs

 

ya, all you are doing is taking out the restrictive supply line so there is less backpressure on that walbro therefore it won't crap out with the higher rpms.

It would probably be wise to add better fuel rails for more flow too but i definitely would start with the tiny supply line.

With the return system you could get more out of your system IF you weren't running out of fuel pump. So cranking up fuel pressure won't help since the pump is restricted by that small line.

also, just changing that line won't change your tune since you aren't altering anything, just removing the resistance from the pump to the rails.

 

Also, I think that the fluctuation in Power Readings was because of the Fluctuating FP, and the FP Fluctuation is not consistent at a given PSI and RPM.

 

i still think upgrade the lines and see how that works. It won't be a wasted upgrade since you will have to upgrade them anyways to use a larger fuel pump (effectively) later on if you decide that the 255 is out of juice.

More than likely it is out of juice. Hopefuly the added larger lines will get you a little less backpressure thus maximizing your walbro for the time being.

 

O.K. Since my last post in this thread I've Installed:

1. CJM Stage 2 Fuel System (very nice High Quality)
2. DW300 Fuel Pump
3. Breather/catch can
4. Base FP set @ 50psi

1. Instantlly Drivability Issues were gone....
2. Closed Loop easy to tune.
3. Open Loop Pain in the ***......
4. Car is making More Power
5. With a little cooler weather (70*) car is now making 16psi by 6700rpm

AFR's are Very Choppy and Wavy, will go from 12.3 - 11.0 and 11.75 - 10.80 afr in less than 250 rpm's, So that the top of the wave is way to lean and the bottom is to rich, Seams near imposable to Tune out and get flat, I'm still working on it....

Afr's were much flatter before but still had waves, any Ideas.

Also, Tires spinning after 4700 rpm in 3rd gear makes it harder to tune, the dip in boost log is from tire spin.

Log is WOT from 2900-6130rpm

please see attached Log