Still stalling on coastdown

[ns158sl]

I have 2 questions, maybe related to eachother.

Main issue is the stalling on coastdown. I have worked on the VE, idle coast spark, coast decrement steps, prop and integral coastdowns. Seems like some things make it a little better but overall nothing is really working. VE looks jacked right now, but this was the first iteration of changing the boundaries again. I dialed in the vve each time ive changed the boundaries. Also I am going backwards and failed the MAF to just rule out all noise from fueling. I cant seem to have this one handled.

Second, is hot start(restart). I think it is much better fueling by upping the OL IVT table, but when the truck stalled in the middle of an intersection, the restart did not go so well lol. Other thing I noticed is during a non panic start, when the ECM goes into closed loop, the AFR goes lean yet the InjPW doesnt change enough to justify why the AFR goes wildly lean and then the fuel trims try to bring it back down

These are smaller files of the original logs. If you want the full ones, let me know.

Thanks!
Eric

405 cu in, ported ls3 heads, l92 intake, ls3 TB, longtubes, truck norris cam, 10.8 to 1 compression.

[hjtrbo]

You have a lot more to do as you've acknowledged.

No promises, but this might help get it running a little better so you can get on with the rest of it. All the coast decrement steps, prop and integral coastdown tables you changed, return those back to stock as well.

Good luck.

[edcmat-l1]

Without even looking at anything sounds like you need to add base idle airflow and cranking airflow.

[hjtrbo]

Without even looking at anything sounds like you need to add base idle airflow and cranking airflow.

Spot on. it was very low

[edcmat-l1]

Spot on. it was very low

It's basic E38 tuning 101.

[ns158sl]

So thats where I was getting confused. I was following smokeshow's advice on a similar setup and he was saying startup airflow usually drives the startup RPM into a flare causing spark retard.

BRAF i thought was just a "minimum," so again, me ASSuming, I was going after the VTT tables being they have a contributing effect on idle control.

As far as the cranking VE, i was trying to use cranking fuel FA, that did not go well, lol. So i reverted to the OL IVT table. I am going to flash Hjturbos flash in and go for a drive.

ETC tipin tq. I tried finding any info before on that, and came up with nothing.

Thanks again!

[ns158sl]

Well it not like stock idle controls, also it did not like any of the startup changes. I feel like I might revert back to where I was and keep honing it in.

Minimum airflow took most of the stalling rolling to a stop sign. It does not like to change p/n to D but I can start to play with those adder tables again later. Main thing is getting my fueling straight. Which it is pretty close just after that drive. So without putting it on a dyno to make sure, I am thinking my fueling isnt giving me grief on my idle.

Thanks again.

[hjtrbo]

You've got about 22g/s of air flow when the idle stabilises. Can you double check your injector data and fuel pressure.

[ns158sl]

I guess I don't see where it is 22g/s at idle? As far I know this is the correct data for the L96 injectors. Blindsquirrel even found me the exact data for an E38 ECM. They were actual GM purchased from Summit Racing.

Ive been using this as an understanding on mine.

https://forum.hptuners.com/showthrea...rottle-to-Idle

[hjtrbo]

[ns158sl]

Ah. I guess I thought that was fine for a colder start, 1000 rpm?

[hjtrbo]

Yeah true, might be ok.

Just need to get the thing to idle steady at normal running temp at your target rpm for long enough to get a read on your airflow so you can start to build your min air table. Use throttle if required to settle it.

[Alvin]

I have 2 questions, maybe related to eachother.

Main issue is the stalling on coastdown. I have worked on the VE, idle coast spark, coast decrement steps, prop and integral coastdowns. Seems like some things make it a little better but overall nothing is really working. VE looks jacked right now, but this was the first iteration of changing the boundaries again. I dialed in the vve each time ive changed the boundaries. Also I am going backwards and failed the MAF to just rule out all noise from fueling. I cant seem to have this one handled.

Second, is hot start(restart). I think it is much better fueling by upping the OL IVT table, but when the truck stalled in the middle of an intersection, the restart did not go so well lol. Other thing I noticed is during a non panic start, when the ECM goes into closed loop, the AFR goes lean yet the InjPW doesnt change enough to justify why the AFR goes wildly lean and then the fuel trims try to bring it back down

These are smaller files of the original logs. If you want the full ones, let me know.

Thanks!
Eric

405 cu in, ported ls3 heads, l92 intake, ls3 TB, longtubes, truck norris cam, 10.8 to 1 compression.

This is rich in decel. This is almost always the cause of idle dips. You shouldn't have to mess with prop or integral idle airflow stuff. Typically people work on these to save it from stalling when the real issue is it is just too rich on decel.

As far as the hard start. It's likely cause your 0-200 RPM of your VVE table has NEGATIVE values. You might have to change the axis's to see this. I can post a picture if you need.

[ns158sl]

I have not checked the lower cells of the VVE probably since i started this months ago. I changed everything 400 rpm and down kind of matching the curve, right or wrong, that has to be better than -1000 in the 200 rpm 90 kpa region, lol!

So I tried to rule out the rich decel by trying to get a steady load in the decel cells which is next to impossible without a dyno. But, when i go back and check it, it seems only around 2- 5 percent rich the last time it stalled coming to a stop?

Either my adaptive spark needs a complete go around, otherwise this thing does not have a steady idle unless i reduce the prop quite a bit, and I think i raised the integral a tiny bit the last time i tried to smooth out the idle. The joke is, in my opinion, i have the idle speed too high as it is for this baby cam granted the 107.5 LSA is pretty much what im fighting.

Also, seems to idle around 10.5g/s in p/n, around 11.5 in gear.

Thanks

[Alvin]

I have not checked the lower cells of the VVE probably since i started this months ago. I changed everything 400 rpm and down kind of matching the curve, right or wrong, that has to be better than -1000 in the 200 rpm 90 kpa region, lol!

So I tried to rule out the rich decel by trying to get a steady load in the decel cells which is next to impossible without a dyno. But, when i go back and check it, it seems only around 2- 5 percent rich the last time it stalled coming to a stop?

Either my adaptive spark needs a complete go around, otherwise this thing does not have a steady idle unless i reduce the prop quite a bit, and I think i raised the integral a tiny bit the last time i tried to smooth out the idle. The joke is, in my opinion, i have the idle speed too high as it is for this baby cam granted the 107.5 LSA is pretty much what im fighting.

Also, seems to idle around 10.5g/s in p/n, around 11.5 in gear.

Thanks

in your log it was bouncing in the low 13's on decel. This is a issue. Along with the negative values in the low RPM section of the VVE table. If the idle should bounce down to those negative values it would for sure stall.

[ns158sl]

I just tried to take it for a quick log. Idle is still horrible still after putting it all back to stock. I am running 14.10 stoich being its on e10. Surprisingly the VVE change down low didnt help with start up so I already jacked the OL IVT back up just to get it start and run for now.

[Alvin]

I just tried to take it for a quick log. Idle is still horrible still after putting it all back to stock. I am running 14.10 stoich being its on e10. Surprisingly the VVE change down low didnt help with start up so I already jacked the OL IVT back up just to get it start and run for now.

that doesn't mean your wideband thinks 14.1 is stoich

Use EQ or lambda to avoid that pitfall.

[ns158sl]

That is a whole another deal lol. It is a AFR500Can that reads out in lambda. For the life of me, I could not get it to show lambda on hptuners on the scanner, but I could get AFR to read. I started a thread awhile back in the scanner forum and didnt get any traction so I just been living with it.

[Alvin]

Search for topics started by me. I have one exactly for this situation.

[ns158sl]

I looked, but i am using this one over CAN to make sure I dont have any voltage discrepancy.

For now, I put the prop and integral back to stock. It is like the PI controller for idle is way out of whack at idle. You can see it overshoots and never finds home. I already have the spark over/under pretty conservative. Now I feel like I am starting from scratch, lol.

Here is a screenshot of my idle instability. Ive watched countless videos and searched the forums. I guess I wish there was a more straightforward way to dissect the PI controller in action through the scanner, being this OS does not have Idle Airflow PIDs. It acts like Integral isnt active, or it is the other way and is in windup and amplifying the problem at hand. This is Stock Idle airflow tables.