Frustrated with twin turbo LS

[Twinning]

Good Morning All,

Long story short, I've been building this truck for over 4 years, spent way to much and made a lot of mistakes, hopefully someone can help me with the last hurdle.

Over the winter I sent my truck out of state for some mods to be done (new headers, injectors, intake etc). there are only 2 decent shops I trust around my area (upstate NY) and they're always slammed, so I sent it out if state. I was supposed to have a dyno tune but because the truck is a long bed it wouldn't fit on it so they did a "street tune", great shop but the tune isn't great and the truck just isn't running right.

To start here's what were working with.... and yes I know the turbos are too big for the motor but I wanted a wow factor, just should have bought a bigger block...I know for next time.

I have a 1959 Chevy Apache with the following: 5.3 LS with forged internals, twin GT35s (not sure the boost, maybe 12 lbs), 1000 DW injectors. First stage twin turbo cam from lil Jon's, 4L80E tranny with hd kit, 3600 stall torque converter from PTC and a Ford 9" rear with 3.55 gears.

The problem:

The initial start and idle were ok but now it is very rough but levels out only if I hold the gas pedal at around 1500 - 2k rpms for about 10-15 seconds. Then I'm told it goes into closed loop and finally idles semi normal. Even if I let it "warm up" for 20 minutes it wants to stall out when I put it in drive and begin to go. Once driving it stays running but feels real sluggish off the line. Once your cruising, at any speed, it feels as if it's misfiring or starved for fuel, you feel little shudders in the motor.

If I'm cruising and stomp on it downshifts correctly, builds boost but the waste gates will start popping like crazy...it doesn't feel normal. If I stomp on the gas from a stand still it will take off fine and maybe spin the tires. Typically it will build boost and THEN begin to spin the tires or hop the rear tires.

Transmission shifts fine, I had diagnostics checked by a local company. I also thought about the possibility of the torque converter being locked but was told it was bypassed in the tune or I wouldn't be able to drive it. Another 4L80e owner said I need a wire run to the brake pedal to release the converter....maybe that's the initial stall issue?

So far I have the current tune file and taken a driving log with idle, cruising and some high rpm rips.

I'm stuck with this awesome truck and terrible tune, It should be a beast but it has a hard time getting out of its own way. I need any and all help I can get. If anyone can remote tune, I don't mind compensating for your time either. Please let me know what other files I can post, I'm new at using the software but I can follow videos/directions.

cold start and drive.hpl
6-17 apache current tune.hpt

[Tre-Cool]

man oh man...

so many things in that tune that look bad imo.

first thing first, if you haven't already get some widebands in that bad boy. time to invest in a set of aem x-series widebands. (I always run 2 on a boosted car to compare sides).

once you have a decent wideband setup, doing some typical street driving/idle work will more then likely fix your cold start issues once your adjusted. I'm also skeptical on what your fueling is like under boost, it's calling for 11.3afr on a forged motor with 12psi is way too rich imo. I'd target 11.8 or 1.25 eq myself.

they are also asking for additional timing to be added in the afr spark correction under additional fueling too. i'd zero that out too.

speed density/ no maf too by the looks? but maf isn't set to error.

[Twinning]

man oh man...

so many things in that tune that look bad imo.

first thing first, if you haven't already get some widebands in that bad boy. time to invest in a set of aem x-series widebands. (I always run 2 on a boosted car to compare sides).

once you have a decent wideband setup, doing some typical street driving/idle work will more then likely fix your cold start issues once your adjusted. I'm also skeptical on what your fueling is like under boost, it's calling for 11.3afr on a forged motor with 12psi is way too rich imo. I'd target 11.8 or 1.25 eq myself.

they are also asking for additional timing to be added in the afr spark correction under additional fueling too. i'd zero that out too.

speed density/ no maf too by the looks? but maf isn't set to error.

Hi Tre and thanks for the reply! Widebands are a great suggestion, I always knew I needed gauges but always forgot to get them because I was busy putting out fires. When you say once its adjusted, do you mean you adjust boost with these?

I am a total noob when it comes to actually using the program to tune but could follow directions if you could tell me where to actually change things. I forgot to add that I have a 3 bar MAP Sensor.

[5FDP]

Widebands are used to calibrate the fueling.

The idea is to create an error graph that shows the error between the commanded AFR/Lambda and the real AFR/Lambda reported by the wideband. That error percent is then put towards the VE table in this case because it's speed density.

If you want the engine to live you better stop flooring it. There are plenty of threads and youtube video's out there about tuning, they should help you understand more of what you have to do. Fixing the fueling is the first thing that should be done, all the idle settings and timing stuff works way better when it's not fighting a rich or lean condition.


Add all these channels to your logs too. Commanded AFR or EQ ratio. Knock retard, cylinder airmass, injector pulse width avg for both banks. Remove the 1 bar MAP channel and replace it with the 3 bar MAP channel so it can read over 105kpa aka boost.

[Twinning]

Widebands are used to calibrate the fueling.

The idea is to create an error graph that shows the error between the commanded AFR/Lambda and the real AFR/Lambda reported by the wideband. That error percent is then put towards the VE table in this case because it's speed density.

If you want the engine to live you better stop flooring it. There are plenty of threads and youtube video's out there about tuning, they should help you understand more of what you have to do. Fixing the fueling is the first thing that should be done, all the idle settings and timing stuff works way better when it's not fighting a rich or lean condition.


Add all these channels to your logs too. Commanded AFR or EQ ratio. Knock retard, cylinder airmass, injector pulse width avg for both banks. Remove the 1 bar MAP channel and replace it with the 3 bar MAP channel so it can read over 105kpa aka boost.

Hi 5FDP, thanks for the reply! I haven't floored it much, I did it mainly for the logs because I thought it would be helpful for some reason haha. I will look up how to add channels to the log and get some more data. Once I add those things to it is ok to just let it idle to collect data or are cruising logs better?

[mild7]

See this thread for some basic help:
https://forum.hptuners.com/showthrea...s-Video-Guides

[lukearmstrong1990]

looking at your VE table id say your "shudder" and desire to stall is from being very lean. The idle and cruise area of your VE table has very low numbers in it and doesn't look like it typically would transition in 3D. your STFT suggest also its lean in cruise etc.

I would be changing multiple things in that tune but the VE table is where I would focus to fix your problem.

Also zero out stall saver and tune your Idle and coast down tables correctly without stall saver interfering.