Throttle Closing Under Boost

Car is a 2010 Challenger R/T with a forged bottom end, a mild cam, and a Procharger D1SC that is making ~13psi.

Had the car running well previously @ 9psi making around 660whp. We added an overdrive crank pulley to bring up the boost, and a meth kit as well, and now the throttle closes at around 4700rpms.

I have tried a few different things, such as raising the airflow limits, raising the PRatio max, VE max, etc. Nothing really seems to affect it.

I have the timing very conservative right now while I try to figure this out, and the forged pistons are causing some false knock, so keep that in mind when you look in the log. The throttle cut happens right around the 2:40 mark.

Any thoughts?

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How about any kind of torque management? Are you now making to much torque causing the engine to close throttle to lower torque numbers? I have not looked at your file or log yet.

Need to MAP clamp it, there is a limit inside that PCM that will close the throttle right around 14-14.5psi. Can purchase one off of Ebay, set the voltage so that it never sees higher than 4.6-4.7 volts and you will be fine. No tuning software yet has found the limit inside that PCM, not CRM and not HP Tuners.

Yeah, I'm aware of the limit, but I don't think that is it because it happens at ~9-10psi. I've never gotten it up anywhere near 14.

I do, however, think that I found the issue last night.

The meth kit I installed was the new style from Snow that uses a plate behind the throttle body (similar to a nitrous plate). With the 90mm TB that is on the car, one of the nozzles sprays directly down on the throttle blade. My theory is that when the kit is spraying full tilt (~10psi) the flow of meth is causing the blade to close slightly, and then the boost pressure takes over from there.

I am going to relocate the nozzles to the intake pipe this morning and give it a try. I'll report back.

Just took it out and it has the same problem. There has to be something in the tune that I am missing to account for the additional airflow. I'll order up a MAP clamp just in case, but I still don't think that is the cause. The max kpa I saw in the last log was 165, nowhere near the 205kpa limit.

Now I'm no expert by any means so I could be wrong and probably has nothing to do with your issue but maybe I'll learn something. Your Pedal % power request and pedal expected tables have to be inverse of each other right? If so your pedal % request table needs some changes because it's nowhere near inverse! Once again, I've only a little experience on my own vehicle and just thought it looked funny.

Have tested it plenty of times and they DO NOT need to be in verses of each other. Not sure the benefit or ill effects by them not matching but I haven't found any.

Quote:

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Originally Posted by nickstipe

Now I'm no expert by any means so I could be wrong and probably has nothing to do with your issue but maybe I'll learn something. Your Pedal % power request and pedal expected tables have to be inverse of each other right? If so your pedal % request table needs some changes because it's nowhere near inverse! Once again, I've only a little experience on my own vehicle and just thought it looked funny.

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I haven't seen any adverse effects for this, but hell, I'll give it a shot.

I'm just getting back to looking at the car. I'll post up if I can find a resolution.

Just for the heck of it,try this.
AIRFLOW>GENERAL>LIMITS MAX AIRFLOW.enter maximum value

Also Pressure ratio Limits,take the Maximum cells to a 7 value.
This may not work,but it's worth a try.