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Title: Throttle cut when boost is to low (cold temps) Post by: phila_dot on October 29, 2014, 04:07:39 PM If we start breaking this down, is HBN an issue at this point? In Flyboy's last log (me7log_20141016_214741) I don't see HBN intervening. The corrected load follows rlmxko so it's most likely the KFTARX map, correct? Do we want to modify that map to at least keep our requested boost at lower temperatures? We should probably log frxta_w to see what it's doing. Even at stock boost levels I've had this cause throttle cut on cold days. The last log that I saw did have intervention from KFLDHBN. Maybe I missed the latest. KFTARX can't cause throttle cut as it just limits desired load. I would just set it to all 1. Title: Throttle cut when boost is to low (cold temps) Post by: nyet on October 29, 2014, 04:21:42 PM The last log that I saw did have intervention from KFLDHBN. Maybe I missed the latest. KFTARX can't cause throttle cut as it just limits desired load. I would just set it to all 1. It can cause TC if it gets cold enough to cap the load request low enough. Even with a completely flat KFTARX, ftbr will rise with a falling tans, causing load request to drop. Conversely, even with flat KFTARX, ftbr will fall with a rising tans ..... Title: Throttle cut when boost is to low (cold temps) Post by: phila_dot on October 29, 2014, 04:43:33 PM It can cause TC if it gets cold enough to cap the load request low enough. Even with a completely flat KFTARX, ftbr will rise with a falling tans, causing load request to drop. Conversely, even with flat KFTARX, ftbr will fall with a rising tans ..... How will that cause throttle cut? Title: Throttle cut when boost is to low (cold temps) Post by: nyet on October 29, 2014, 04:45:58 PM How will that cause throttle cut? An improperly tuned PID that can't handle large variation in steady state WOT plsol :) Title: Throttle cut when boost is to low (cold temps) Post by: rekrull on October 29, 2014, 07:08:41 PM How will that cause throttle cut? I'll try to dig up a log and post tomorrow. Title: Throttle cut when boost is to low (cold temps) Post by: rekrull on October 30, 2014, 08:56:15 AM Here are some graphs showing the throttle cut due to drop in IAT. This was in 3rd gear (TIP).
(http://i1383.photobucket.com/albums/ah295/crap4paul/KFTARX_throttlecut_load_zpsc31a7ce3.png) (http://i1383.photobucket.com/albums/ah295/crap4paul/KFTARX_throttlecut_boost_zpsc4238674.png) (http://i1383.photobucket.com/albums/ah295/crap4paul/KFTARX_throttlecut_iat_zps5c77fc56.png) Title: Throttle cut when boost is to low (cold temps) Post by: FlyboyS4 on October 30, 2014, 09:32:00 AM Am I reading that correctly, IAT around 0 deg. C?
Title: Throttle cut when boost is to low (cold temps) Post by: phila_dot on October 30, 2014, 09:35:08 AM Definitely something else going on.
Look at specified and correct load. Title: Throttle cut when boost is to low (cold temps) Post by: nyet on October 30, 2014, 10:38:41 AM Looks like req boost is falling below wg pressure, and the ECU is using the throttle to modulate boost.
Title: Throttle cut when boost is to low (cold temps) Post by: rekrull on October 30, 2014, 01:35:29 PM I don't want derail things here too much. I noticed the car was surging under certain conditions. After logging, it appeared that the initial drop in IAT dragged down the requested load via the load correction factor for IAT. I ended up setting the lower temp part of the KFTARX map values to 1 and the car ran better. This was almost 2 years ago, so I haven't thought about it lately. I'm open to suggestions. I'm not a tuner. I'm just a guy who has dabbled in tuning my own car. I've uploaded the log file in case someone is interested.
Am I reading that correctly, IAT around 0 deg. C? Yes, it was January in Massachusetts.Title: Throttle cut when boost is to low (cold temps) Post by: nyet on October 30, 2014, 02:24:32 PM I don't want derail things here too much. I noticed the car was surging under certain conditions. After logging, it appeared that the initial drop in IAT dragged down the requested load via the load correction factor for IAT. I ended up setting the lower temp part of the KFTARX map values to 1 and the car ran better. This was almost 2 years ago, so I haven't thought about it lately. I'm open to suggestions. I'm not a tuner. I'm just a guy who has dabbled in tuning my own car. I've uploaded the log file in case someone is interested. Yes, it was January in Massachusetts. I'm actually not surprised. KFTARX might not be the best place to fix this... but until I completely figure out the temp correction in the load->boost calc path, it is the best we have. Note that a COMPLETELY flat KFTARX will still result in a lower req boost in cold weather, and more req boost in hot weather (for a given load request). Title: Throttle cut when boost is to low (cold temps) Post by: Lost on October 31, 2014, 12:29:59 AM Did you take a look at LDIATA? Is it all 1 as well?
This map will bump your boost in warm weathers and lower in cold. Title: Throttle cut when boost is to low (cold temps) Post by: phila_dot on October 31, 2014, 06:05:27 AM The spike and sharp drop in target boost pressure don't look related to rlmax_w.
What does rlsol_w look like? Did you take a look at LDIATA? Is it all 1 as well? This map will bump your boost in warm weathers and lower in cold. This is only for I-limit. Title: Re: Throttle cut when boost is to low (cold temps) Post by: nyet on October 31, 2014, 11:28:58 AM Did you take a look at LDIATA? Is it all 1 as well? This map will bump your boost in warm weathers and lower in cold. Absolutely wrong. LDIATA is there to compensate the PID for changes in steady state boost request due to temps. It does NOT change requested boost. Title: Re: Throttle cut when boost is to low (cold temps) Post by: Lost on October 31, 2014, 11:51:39 AM Absolutely wrong. LDIATA is there to compensate the PID for changes in steady state boost request due to temps. It does NOT change requested boost. Correct. It changes actual boost. Title: Re: Throttle cut when boost is to low (cold temps) Post by: nyet on October 31, 2014, 12:13:08 PM Correct. It changes actual boost. Which would be *lower* in cold weather with the stock LDIATA (if the PID was riding IMAX), so there would be no need for TC.. Title: Re: Throttle cut when boost is to low (cold temps) Post by: rekrull on October 31, 2014, 01:33:03 PM You guys need to warn me when you spin this off.
In response to phila_dot's question about rlsol_w The requested load (rlsol_w) follows the corrected load (rlmax_w). It's included in the log I posted if you want to take a closer look. The math works out for the IAT correction factor. |