can't find out what's causing this throttle cut at high rpm. anywhere from 5500 to 5800 it happens. get the throttle light on the dash, no codes and Key on key off, it's gone.
making 8psi at this point.
any help appreciated.
can't find out what's causing this throttle cut at high rpm. anywhere from 5500 to 5800 it happens. get the throttle light on the dash, no codes and Key on key off, it's gone.
making 8psi at this point.
any help appreciated.
Looks to me like you're running a factory MAP sensor. How is the PCM supposed to compensate with fueling when it doesn't know you're running 8 psi of boost? The most it's able to see with the stock MAP sensor is 109 kPa (about 1 psi boost).
On top of that, you're also getting close to maxing out your injectors (are they stock also?). You're reaching 84% IDC when the throttle closes on you, and that might be what is causing the throttle to close. But you have a lot of things to get ironed out before you keep going.
Do you have a wideband installed?
i dont have the answer for that, but i think you need to use 2 bar map and re-scale VE table to account for boost too.
this is the original sct procharger tune. yes it's stock map sensor and it's been running like this for 5 years. it can and has been like this on LOTS of cars. i know it's not the best way, but it works. the change is a +2 psi and switch to hpt so i can program the transmission (sct has no trans control). i did scale it up to all the map sensor can see (1.1 pr), but i don't think the map sensor is the issue since it was fine at 6 psi. given that it didn't know it was 6 before and 8 now.....
As stated before, the cut is possibly due to running out of injector. Typically you never want to run IDC past 85%, and the stock PCM may have a limit that causes cutout/throttle pull if you approach that limit.
Do you have a wideband at least?
Last edited by B00STJUNKY; 09-09-2018 at 05:57 PM.
same ecu as an srt4 and it doesn't care at all if you do 100% dc. neither does any gm ecu i know of. if you hit 100% it doesn't do anything to the injector or the ecu, the injector is just energized the entire 720 degrees of engine cycle. if more fuel is needed, it'll just go lean.
afr is fine. because of the 1-bar map sensor i had to ramp in the PE as the boost goes up with rpm (procharger), but there's no problem getting enough fuel.
this is most likely a calculated airflow vs something and that's why it gives the throttle light in the dash. but not finding where it needs that change made. a code would help but no code.
Well, similar ECU, I would say. For 1, the NSRT-4 ECU is NGC1 (for some 2003 model year) and NGC3 (for 04-05) with SCI communications protocol, whereas yours is NGC3 with CAN communications protocol. Also, the SRT-4 doesn't utilize Drive-by-Wire, and as such, the torque management in the SRT-4 would obviously never pull throttle to manage torque. Instead, it would manage torque via boost and timing.
Attached is an image taken from an SRT-4 calibration, along with a spreadsheet that calculates IDC from Pulsewidth showing very clearly that there is a Torque Management protocol for Injector Duty Cycle (or, rather, a pulsewidth vs RPM limit). Granted, it appears that it limits pulsewidth to an equivalent IDC range from 92% to 97%, depending on RPM. At this point, Torque Management would kick in in the form of pulling boost (assuming stock boost control was in use - which, let's face it, was rare even for stock turbo guys to keep in control).
SRT-4_Pulsewidth-Limit.jpg
Now, with your PCM using drive-by-wire throttle control, it's possible that running into an IDC/Pulsewidth limit could result in throttle pull. Now, if you're certain that's not the case, then so be it.
I looked at your airflow in the log vs your airflow limits in the Diag tab of your calibration, and if you were going to be running into an airflow limit, it would be happening around the 4800 - 5200 RPM range where your logged airflow peaks. Again, I've attached some images below that show the linear interpolation for the RPM and corresponding logged airflow at areas that might be questionable. You'll see that at the 4916 RPM log, you're right up against your Airflow Max RPM limit, but not surpassing it. But earlier in the pull, at 4795 RPM, you have surpassed said limit, yet it didn't shut you down.
Airflow-vs-rpm2.jpg
Airflow-vs-rpm.jpg
It could also be a transmission torque management limit that you're hitting, but it's hard to know or even look since you haven't read out the TCM. But, you could experiment by selecting "Disable" in the "Auto Trans TqMgt" "Use ETC A" parameter ([ECM] 44833) under the [Engine] [Torque Management] [General] section of the calibration.
Last edited by B00STJUNKY; 09-09-2018 at 08:30 PM.
ok, thanks very much for that.
for whatever reason, this is the same trans as we have in the usa, but this is a mexico truck.
i've looked at the trans and it does all the same things as usa truck (hit tow/haul 2x to lock it in 4th for the dyno) and it looks NO different than the usa trans but it won't read.
bill just says not a supported trans. there's just something different enough about it when it goes to unlock it for a read, that it hits a road block and shuts down.
there's no option in the software read it as the 545 either so i'm just stuck.
looking through all you've said, looks like a HIGHLY likely situation.
test drive with just 1-2 gears doesn't trigger it but ultimate test is 1/4 mile since that's what customer loves to do.
i'll try to plead with bill on way to get a trans read. it's supported, we just need different way in.
The "Use ETC A" parameter is PCM side, so you should be able to disable it in your calibration anyway (just follow the path I mentioned to you N my previous post). But, if the TCM is sending any of its own Torque Management signals directly to the ETC, rather than relaying them through the PCM, I suppose it could still pull throttle. But I think most TCM signals are relayed through the PCM.
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