Issue with returning to idle on decel.

[Pitman]

New to tuning here. Ive tried several different adjustments to the stall saver and that has helped. The tune that i am working with was created by texas speed for their cam i am running. I do not remeber the specs on it but i will be calling monday to confirm them.

When the engine dies, its always happens on decel once the clutch is depressed after engine braking. It also only occurs with the engine warm. Does not happen below operating temp. Everything functions well up until operating temp.

One issue i am running into, i have ls swapped an 86 chevy therefore i dont have a speedo input into the ecm. From what i can tell, the throttle cracker and throttle follower use speedo input on their tables which look to render them usless in my situation.

Can anyone shed some light on wether they can/will have any control since i am lacking that input? The Engine/ECM combo are out of an 06 5.3 half ton chevy.

Im going to attempt to attach the tweaked tune and a log. First time uploading those as well.

[Jamie F]

what if you try adding your idle rpms into the rolling idle rpm table instead of all zeros?

[4drz06]

I have the same problem. Still Don't know what the actual fix is as I have asked and didn't receive much help here.

What I did do as a band aid for the situation was I enabled the throttle cracker function and it seems to keep it from dying out when coming top a stop. I have it enabled at 45mph then disable it at around 20-25mph

Probably not the correct way to do it but it sure is better than having the car die out randomly, especially when turning and having to push the clutch in. I'm sure you probably experienced that one already lol

[4drz06]

Try tuning your MAF. I did that today and it seems to have solved the stalling issue when pushing the clutch in. Set up your scanner to log MAF Hz against your STFT then copy and paste the error and multiply by percent half. Keep doing it until you get your MAF Hz logs in the scanner to read +-5%

This ended up working for me. Hopefully it'll work for you. Your VE table and Spark Tables both look good to me. But I'm just starting out tuning here like you. Let me know if tuning your MAF works out

[Jim Brown]

4drz06, He's not to that level yet.
If you look at his tune, throttle follower, throttle cracker, and stall saver, are all inadequate or completely shut off.
Lots of tweaks on ALL the idle control valve (IAC) stuff is needed.
He's not necessarily stalling because of mixture problems.

Hey Pitman, get a Wide Band O2 Gauge mounted on top of your dash before you do anything else.
It will be invaluable for diagnosing problems now, and tuning later.
There is no such thing as an excellent mail-order tune.
It's just to get you up and running. And too many times, it's just to take your money.
I hope you didn't bite off more than you can chew.
If you still have a copy of your original tune, I would advise that you set it up as a "compare file" and
copy and paste EVERY single "IDLE related" number and Table from your stock tune to your new tune, as a stable "starting point",
you will have to figure out how to tweak it. And, if you're running a choppy cam, it's going to be some work to get it right.
What you have now is not likely to work well, but DO save a copy before you start making changes, there "might be" some
valuable stuff in that tune that will help you to at least stay running.
DO NOT beat on it until you at least have a Wide Band and know that it's not lean under heavy loads.
Tuning takes many hours, on each individual car, even when you know what your doing.
Race cars are actually pretty easy, partly because they usually run well documented aftermarket ECUs and don't care much about driveability.

[Jim Brown]

BTW,
You NEED a speed sensor.
They are available.
Get one.

[Pitman]

Jim, from what i am understanding from the literature supplied by hp tuner, the throttle cracker and and rolling idle both need speedo or clutch inputs for them to work effectivley. Of which my setup does not have. Does that rule them useless or does the ECM have some sort of baseline it uses without those inputs?

[Jim Brown]

Sorry about the delay getting back.
I used to be a Mega-Squirt expert, but to be truthful, I'm still learning GM computers and HPTuners software.
I was basing my replies off of MY personal aggravation with getting rid of all
the "anti-high-vacuum-condition" emissions related junk that is
an absolute requirement in a factory emissions tune.
When I take my foot off the gas, I want engine braking, right now, and consistently.
A little "Snap-Crackle-Pop" from the exhaust on deceleration can be kinda cool as well,
which you will never have with a proper factory emissions tune.
I spent 3 days experimenting until I actually got rid of all of it.
Yes, there are some manual transmission, "clutch", and/or, "shift" adjustments that are thrown into the mix,
which you can ignore, if you had an automatic,
but there are quite a few settings that require specific Vehicle Speed Sensor (VSS)
values for them to operate correctly.
I really can not say, with any authority, what the computer will default to when there is no VSS input, or
if just "zeroing" or "maxing-out" those settings, (if you don't need those particular functions at all), will do.
( I have an automatic trans and I appreciate all the extra features)

Part of the reason for keeping the highly complex and thinly documented factory computer is its sophistication
and huge number of tune refining features.
It was never designed to be a "universal", "Hot-Rod" or Race-Car computer like a Mega-Squirt, so
I would suggest that you provide it with any and all possible inputs that
it "expects" to see and operate from,
and then learn how to take full advantage of all of the bells and whistles and
refinement of control that the factory computer has built-in.
A VSS sensor "may" or "may-not" be needed , or useful, for your particular application.
Same goes for a clutch switch.
Finding out whether or not you "really" need these items, and
finding out from someone who "knows-for-a-fact" that it will or will-not cause you tuning aggravations,
now, or down the road,
may be more difficult, and time consuming, than simply swapping out your
transmission tail-shaft housing for a later model housing with a factory built-in VSS Sensor
which you can probably pick up in a junk yard for less than $20 bucks.
And, you probably already have a clutch switch, which should be hooked-up
if for no other reason than to eliminate 2 more additional wild cards that are now
thrown in to the tuning equation.

I can tell you, from my direct experience, not only with huge choppy cams back in the day,
but also with the throttle-follower and throttle-cracker, and stall-saver functions, that,
if the car was in front of me right now,
I could put in a 75 to 80% fix for your problem on the first try......
HOWEVER....
There are quite a few other factors that could be present in your combination that could make it
nearly impossible to create a solid fix for your stalling problem.
SOME of them are....
Quite often people purchase a cam based on the "sound"....
They want it to sound like a Nitro Funny Car at idle.
If this is your case, CHANGE THE CAM , unless you just want a trailer queen......
Tell the conservative TRUTH to your cam supplier and he will
deliver the correct cam for your wants and needs.
If you don't have enough compression for the duration and overlap of your cam,
it will ALWAYS be a continuous battle to keep the thing running at idle,
let alone smoothly settling down to the idle you "think" you want.
Huge Choppy Cams will NOT idle below ~1200rpm without VERY high compression ratios,
and if you do get it lower it will be a total pig in the mud with
very "iffy" and inconsistent low speed torque, idle and driveability problems.
If this is you, you need a "controlled-leak" carburetor like a Holley, or
a very specialized "Open-Loop-Speed-Density" tune.
Or you could just have a basically wacked tune, mixture wise, and/or, timing wise,
with a completely stock engine,
Or a hundred other small details not working together in harmony.
Does your engine have a thermostat ??
Is your cooling system adequate to keep your engine temps "riding-the-thermostat" and 100% stable ?
Do you have a massive over-kill electric fuel pump ?
Do you have a properly sized fuel return line back to the tank ?
Or do you have a "return-less" fuel system with an after-market pump ? or pump not controlled by the PCM ?
I could go on for hours, the "devil is in the details".

Your "Cranking VE" table looks pretty strange,
like someone was doing a down and dirty hack job instead of adjusting the priming pulse, etc., but
I don't have a stock LS file to compare to.
Your Deceleration Fuel Cut-off (DFCO) should be completely disabled, this could be part of your problem.
Your Main VE Table is not tuned above 6000rpm, and could at least use some refinement,
are you running a MAF Sensor ?
You "might be" in danger of running lean above ~5000rpm, from an off-hand
guess of your engines capabilities.
I would be doubtful that your torque curve is "that" peaky,
but I could be off in my estimation, you may have a very "peaky" cam.
What are ALL of your cam specs. ??
What type of exhaust are you running ? and header specs if you are running them.
What is your static compression ratio ?
Do you have a working "Check Engine Light" ?
(SES light), (MIL light), (DTC light) (all basically the same thing).
Do you know the value of it ? If you don't, or don't want one, (you can hide it below the dash),
you should probably be running an aftermarket, "self-tuning" Engine Computer instead of the factory PCM,
or a Holley carb.
You may actually be better off with a factory tune as a starter tune.
But I'm really just guessing at your configuration at this point.

.................................................. ...............Jim