parking lot surge/stall

[04silverado6.0]

04 silverado, 6.0 lq9 .020 over, btr stage 3 v2 truck, circle d 258mm 3400-3600, gen 4 truck intake, headers, 243 head, rpm lvl 6 60e. Still having trouble at parking lot speeds, particularly after a long idle or after fueling. The rolling idle helped a lot during coastdown but blipping the throttle in a parking lot will still result in a stall or surge. Anyone need to raise the idle in gear with a converter swap? Truck had the same issue with the 278mm 3000-3200 but was actually able to tune it out. The new stall brought this back but worse.

[04silverado6.0]

Much better with the changes made. Still not cured.

[abc]

My first thought is: a looser converter should need less torque in the area you are describing to keep it idling. Could it be the looser converter is allowing the rpm to drop faster therefore needing more throttle follower, decay it longer? Have you tried adding more fuel below and at the target idle area? Obviously I'm spit balling here, but could adding fuel in the transient ECM 12284 possibly help? It does look like it's going lean during the dip in idle but I'm not sure if that is a chicken or egg thing.

[04silverado6.0]

I see the o2 voltage dip but im not sure if thats a symptom or a cause. Ive adjusted transient fueling tables but it seems to fix one issue and cause another. I figure my ve in the lower columns already is a little fat?

[abc]

As you know, it's a simple test. Add 5 percent fuel below the target idle speed and maybe 2 percent to the idle for a quick test.

I still think I would go after the throttle follower first.

[blindsquirrel]

Stall speed isn't affecting it at idle/off idle, it's to do with the change in diameter/weight/inertia.

[04silverado6.0]

This was only a change of 20mm but i could tell a lot of weight difference installing. Same issue as a lightweight flywheel in a manual. Just curious if there is actually a cure in these controllers? Some things have helped but the underlying cause is still present.

[edcmat-l1]

There definitely are some tricks to making this work especially in a P59. But first off you're not logging throttle cracker and follower airflow.

Long term idle trims are constant -.8 g/sec

What injectors?

It would probably run better in speed density.

Not sure if you have the rolling idle setup correctly. You aren't logging the follower and cracker so can't tell really.

[04silverado6.0]

I cannot remember the injector number. I do have the data correct via blindsquirrel.

[Alvin]

A cam with that much overlap cannot use only fuel trims to get the VE dialed in. The fuel trims/learning do not happen fast enough to catch holes in the VE table. It is entirely possible and likely to have rich areas in decel, or just off throttle that causes this dip/stall but fuel trim still show near 0.

Watch timing in the idle spark tables. leave some timing for reserve torque. Set it up to add timing for a dip and lower timing for a run away idle.

[04silverado6.0]

I didnt think 3* was much overlap. This thing hates idling on less than 21-22 advance.

[blindsquirrel]

3* overlap at .006" which is the one that matters for idle quality/reversion, or .050"?

[SiriusC1024]

You see how the O2's are constantly biased rich and the corrections take a long time? See how they have to correct from scratch every time (hint hint LTFT)?

Zoom in on a section and look at the STFT error for that spot. Toggle back and forth between view zoom and average. Inconsistent.

Start with stock values for over/under spark, O2 (451mV across is the only change I'd make to start), and complex temp model then see what it does. Retune the airflow models.

When you arbitrarily change/guess at tables the error compounds. It's multiplicative. Like the Dynamic tab. Lot of changes I'm like why? You're not even logging Dynamic Airflow to see if the MAF is off from VE. I kinda see what you're thinking, but I don't agree with the 'ish' pushes.

The O2's, if they need adjusted, should be based on data. https://forum.hptuners.com/showthrea...l=1#post756121

[ns158sl]

Transient fueling "shouldnt" be active during idle, I just went through this myself. Most likely it is your VE like Alvin stated.

Honestly just glancing at the tune. I would start from stock, redo fueling in SD, adjust Idle airflow if need be, then reenable MAF. 21 degrees is fine. Everyone gets caught up in tq reserve. It is necessary , but not many know how much you should have or what "your" engine already has.

For a reference, seems like stock cals run around 6Nm. A cammed vehicle will need more for erratic torque production. How much is the million dollar question.

[04silverado6.0]

The o2 mv was adjusted for smell. Ltft may be a good idea. I have also adjusted the iat/ect bias to help with trims on cold/hot starts which did benefit especially on the hot starts. The airflow models have been gone over at least 20 times. It has been street tuned up until the last go which was steady state loaded dyno.

[ns158sl]

O2 on smell? Watch injPW vs rpm. Also steady state is the answer literally for all engines. But you will never hit the lower map region. That's where tooning becomes an art.

[SiriusC1024]

Complex temp will affect a lot. Probably end up increasing the error between MAF and VE. For hot starts there's FA Mult Stage that has ECT as the column axis. Also, Soaktime Mult. For hot starts then incorrect fueling until fuel trims kick in adjust the OL table and the cold/warmup modifiers.

The original problem is a combination of VE and O2's not switching correctly.

[edcmat-l1]

The original problem is a combination of VE and O2's not switching correctly.

I don't think so. But give it a shot. Not goading you I just don't think that's the cause or the cure.

[SiriusC1024]

I don't think so. But give it a shot. Not goading you I just don't think that's the cause or the cure.

Your suggestion of throttle cracker and follower is certainly worth examining.

[Alvin]

I didnt think 3* was much overlap. This thing hates idling on less than 21-22 advance.

Trust me. A wideband should be used to get the proper shape of the VE table especially with that cam. Duration isn't crazy but it is on a 110 LSA!

A rich spot in decel or as you are creeping is going to cause a dip/stall. You are not going to be able to get the VE table finely tuned with slow acting STFT and LTFT