Surge/stall when warm on startup

When cold, the car fires right up and idles perfectly. If it's warm, however, it will fire up, stumble low like it is about to stall, then rev and try and catch itself, sometimes it will and find idle, sometimes it will stall out. If I give it a rev on startup like it's carbureted, it fires fine, and settles right into a nice idle. It also seems to drop near stall-low rpm when turning and slowing down (with extra PS drag) or when coming to a quick stop, it won't stall, but it comes low. Drives smoothly, throttle is responsive, just down to this final issue. Still fairly new to tuning, just looking for direction of where to start. Seems like it's maybe dumping too much fuel at startup.
2005 Dodge Magnum RT 5.7 Hemi, .020 bored over, ported heads, torqstorm procharged, longtubes, ported intake manifold, 85mmTB, SRT4 stage 1 injectors, Grams fuel rails, AEM 50-1000 pump, 1 stage colder plugs, shorty wire conversion, DUI HO coils.



most recent log
Attachment 100559
most recent tune
Attachment 100560

The supplied log doesn't seem to capture the start-up

One cold start, One hot start (with stall) log:

Attachment 100607
Attachment 100608

any leads?

I have exact same issue you are having - i have a 3.6 pentastar - this issue only presented itself after the first time i used Hp tuners to read the ecu
happens if i drive the vehicle and then park it up and let sit for more than 20 mins and try and restart

as a kind of... patch I raised the desired startup airflow, it still revs and drops pretty quick, but I haven't had it stall out. It gets close, but hasn't stalled. Not a perfect fix, but I haven't had a ton of time to tune and fiddle with it.

I see a few issues, one being that there is no feedforward idle torque (air or spark) defined in the file, at least not on my version of HPT.

But the big issue is likely the new throttle body. There's a good chance it's not actually doing what you've entered for bench flow and sonic airflow model calibrations. If you say your throttle body flows more than it does, then it will pull the throttle further closed until the idle PID pushes the error into the integral after startup. This is probably why it happens when you come back to a stop as well...all of that air has been ramped out of the integral term. And when you load up the power steering, it will respond with less TPS adjustment versus the torque proportional request, making idle sag a bit.

I could show you a few ways to fix this, depending on how much work you want to do. There's the correct, difficult way, or a couple bandaid easier ways you could try. I used to be a calibrator for Chrysler so I still have some tricks up my sleeve ;)

How does it start after you drive, data-log, get home and try to start again.

Quote:

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Originally Posted by smokeshow

I see a few issues, one being that there is no feedforward idle torque (air or spark) defined in the file, at least not on my version of HPT.

But the big issue is likely the new throttle body. There's a good chance it's not actually doing what you've entered for bench flow and sonic airflow model calibrations. If you say your throttle body flows more than it does, then it will pull the throttle further closed until the idle PID pushes the error into the integral after startup. This is probably why it happens when you come back to a stop as well...all of that air has been ramped out of the integral term. And when you load up the power steering, it will respond with less TPS adjustment versus the torque proportional request, making idle sag a bit.

I could show you a few ways to fix this, depending on how much work you want to do. There's the correct, difficult way, or a couple bandaid easier ways you could try. I used to be a calibrator for Chrysler so I still have some tricks up my sleeve ;)

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I'm all ears! 4th coming up so I might finally have time to play with the tune again. It just runs so well 98% of the time I haven't had the time to fiddle much. The little "desired startup airflow" bump I threw in there seemed to at least prevent the stalling as a total band-aid patch, it revs, falls, revs, idles perfect. It's a BBK 85mm TB which has had some massaging and polishing, with an intake manifold inlet to match, so as a whole, the TB table is bumped up about 1.0625, then brought the amounts over to Small Range and Large Range desired throttle.

Quote:

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Originally Posted by TerrysTrans

I'm all ears! 4th coming up so I might finally have time to play with the tune again. It just runs so well 98% of the time I haven't had the time to fiddle much. The little "desired startup airflow" bump I threw in there seemed to at least prevent the stalling as a total band-aid patch, it revs, falls, revs, idles perfect. It's a BBK 85mm TB which has had some massaging and polishing, with an intake manifold inlet to match, so as a whole, the TB table is bumped up about 1.0625, then brought the amounts over to Small Range and Large Range desired throttle.

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So the part throttle spark tables aren't helping. I get that those changes are in the flare region, but that should be done with airflow, not spark. As for the throttle, you should always monitor TPS voltage since that's what Chrysler has historically used to meet an engine torque request. For the throttle body model, you can't do this properly without a bench test stand. However your idea on multiplying based on new throttle dimensions should get you close. Unfortunately, it isn't as simple as dividing the new diameter by the old diameter. 85/80=1.0625, but the new throttle area divided by the old area is 1.1289. That would be the value I start with, and then of course bring those values into the small and large throttle range tables. And logging some sort of airflow would be useful, ideally both desired and actual. Since the required idle torque is resolved into a desired airflow and then used to determine the throttle position, knowing required air is critical. Add injector pulsewidth as well.

Start with these changes and then we can look further if it needs more detail.

Ah. Yea, I guess that makes a lot more sense since its a volumetric increase, not just a simple.. diameter percentage increase. Also while going through I had found some inconsistencies in where I had copied over the data from the ETC to the small range and large range tables, because the small range table has an airflow max value it caps at and changes any input value back down to (so I had to dig in and do some dreaded MATH to find the correct Voltage) and the Large range table has some jumps in the voltage that it requests data for, not an exact copy from the ETC table. I'll start with fixing those tables and report back in a few days.

Quote:

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Originally Posted by smokeshow

I used to be a calibrator for Chrysler so I still have some tricks up my sleeve ;)

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Sorry for going off topic, but if that is true then you should seriously think about writing a dodge/chrysler specific tuning workbook like the tuning school or Greg Banish and sell it thru Amazon. I for one don't want to be a tuner for a living but I sure would like to get a better understanding of how the airflow (and torque) tables truly work so I can tweak my own ship. Recently sampled air tables from a tune Hemituna uploaded and honestly the response is orders of magnitude better than stock, yet the values are all well below stock.

Another thing that baffles me is the 5.7 and 6.4 use the same controller (different calibrations) yet 6.4s will always read 134 degrees exhaust advance and 5.7 will always read 125 degrees exhaust advance. However, the max-phase, lock-pin, max and min are almost identical?

After a week or so, it seems a bit better, but still does it. It really is more of a minor inconvenience. Starts, revs up (not quite as high now) then falls down (almost like the throttle blade snaps shut) then catches itself before stall with another rev, then all is well.