Reasons the ecu will close the throttle automatically

[Sourskittle]

With the efficiency we've seen from all these aftermarket incoolers, I'm looking forward to seeing what a cooler with double the core size can do with my climate and higher demand than most.

 

[RAAMaudio]

Just made the 3rd run of the day, bringing up boost, 22.4 now with 19.66 at 6500 RPM and not closing the throttle and no timing issues at all.

 

[RAAMaudio]

SS please check your PM or email me or call, etc...I need some info for the tuner, or please get in touch right away. Things are looking good so far, he wants a bit more to go on to know where to level this thing off.....

 

[RAAMaudio]

23.45 PSI, tapered down but still held 21+ from 5800 to 6700 RPM but started closing the throttle a bit again, timing still looks great.

 

[JPGC]

Subscribed!!!

 

[RAAMaudio]

Best so far is over 24.97 PSI and over 23 at 6600 or so......and the throttle was wide open the whole time and not major timing issues, just some fine tuning there.

 

[Sourskittle]

I sent Razor a 3rd gear pull on a flat wet road (for V-dyno ). I tried like 6 different roads before I got lucky and it held past 4400rpms in 3rd. My car is 2900lbs with me in it. 235/40/17 tires. 65 degrees out.

 

[BizarroST]

Hi Everyone! Sorry to bump this, but I am troubleshooting this exact issue - I think. I am seeing the throttle ETC delay to fully open, reading through this it seems to point to the Load to TQ and TQ to Load tables - but I am unsure where to start with 'fixing' those - and on top of that I am seeing it happen several seconds into a WOT pull, with requested TQ pegged to the same value before and after the throttle plate actually moves (383 ft-lbs)

Check out how it will slam open, slam closed (partially) and creep back up to fully open, all while the pedal is to the floor I am stuck. Advice?

https://datazap.me/u/bizarro252/log-1519018647?log=0&data=1-4-5-6

 

[Xaendeau]

Afternoon, this is a good thing from my perspective. This is what the car is "supposed to" do.

Log "tip actual abs psi" to help with seeing what is really going on for your turbo. It is going to read as...maybe 35 to 41 psi. Subract your local pressure (14.7 psi at sea level, lower for you as you are @ 2700 ft), and that is what the map sensor in your cold-side charge pipe is seeing. The sensor is just a bit before the sound symp, before the throttle body. Your car does the boost control from a combination of the wastegate, and the throttle body using the TIP (pre-throttle body) and MAP (post-TB, on top of the plastic intake).

I can already tell you that your turbo is making well above 20-21 psi on the low end. Logging tip actual abs psi will confirm that.

What is happening: your turbo is making maybe 22-25 psi (look at TIP absolute), the throttle kicks in to keep boost under control (using the TIP and MAP) post throttle-body in the intake manifold and hold it steady at 21 psi. This is a "good" thing to some people, like me. Saves your rods from that brutal low end torque, which your car can probably handle anyway. I wouldn't really push the turbo to making 25+psi like some people have. It is kinda pointless, the turbo is a freaking flame thrower past ~22-23 psi...so maybe work your way up the there.

Assuming you keep the throttle+wastegate boost control (you should), try to slowly up the boost to 22-23 psi and see if that allows you more pressure post throttle body. Then, start messing around the the "Load to TQ and TQ to Load" tables.

Also log "charge air temp" because this will tell you when your turbo is just making too much heat for your intercooler to handle. You *SHOULD* have an intercooler if you are running anything more than stock. Very important. This will also "kind of" tell you when you have too much boost as well. If you have a new enough version for the AP, log estimated torque ("est. torque ft-lb"?). Helps us mortals easily digest what is going on at the wheels. It is somewhat accurate as long as the wheels don't spin.

Good luck, haven't messed with those tables myself, but I hope that helps you understand what is going on.

 

[BizarroST]

Hello and thank you for the reply

I should have mentioned some important things in my first reply lol - I do have a FMIC, so even on my tune I paid for (Strat) that hits 23PSI I sit at a cool 10F or so above ambient (at least for now, its cold outside!).

I will check out what you have suggested, I guess I was hoping that the car would preference the WG over the throttle, but it makes sense that upping the boost would lower the throttle intervention, I doubt it will make it go away all on its own though as you mention - thats where these tables come in. I am staring at them, as well as logs from my Strat tune, where the throttle does NOT behave this way at all (will open fully much sooner, and stay open throughout a pull) and am trying to wrap my head around the trick to it.

Things like this make me want to stop the throttle from closing at these mid RPM ranges:

http://fordstnation.com/focus-st-pe...g-kept-open-wot-vs-allowed-close-its-own.html

I hope by doing so I am not removing a critical saftey feature for overboosting, perhaps there is a sweet spot where it will follow the pedal better, but also still be allowed to respond in an overboost situation.

 

[Xaendeau]

Eh, don't beat yourself up too much about it. It *is* the end of winter, so 22 psi at 40 F in the charge pipes is a much different amount of torque to the wheels than 80 F air coming in. I imagine Alex spent a VERY long time making those $50 flash tunes damn near perfect for a safe off the shelf tune, in a wide range of conditions. That is what I was running before I swapped my turbo last month.

The throttle body is just another tool to control boost. ETC angle of 26 deg is pretty heavy handed though. If you can up the boost and that helps, that's fine...else you know where else to look. If you tweak it a bit and get the closure to not be as drastic, it would be fine throttle stays in the 60-80 deg range during WOT. I mean, keeping it above say...50-60 deg at all times would be a victory in my mind. After you think you have it settled, make sure to do a partial throttle run to check and see if the throttle isn't "saw-toothing" across the rpm band.

I mean, if you get to the point of minimal throttle closure, you aren't leaving too much power on the table...and having the peace of mind that the over-boost protection is still ready to step in helps me sleep at night. I am still getting my MRX turbo tuned, and occasionally I'll see a blip (~55-65 deg) of throttle closure if the boost creeps a little bit in a 4th gear pull. No big deal. Safety first, right? Logs say I lose very little torque for a split second when it happens.

 

[BizarroST]

I will monitor what you were talking about and see how it looks, flashed back to my tune this AM but was running a bit behind and just had to come straight to work Since I am 'limiting' boost to 20PSI right now while I get a base map figured out that it likley a large contributor.

I think something may have just clicked for me on how these tables work, I was thinking these were supposed to closely represent actual load vs actual TQ, but (correct me if I am wrong here), it seems like the 'Throttle Requested TQ' z-values of 'requested TQ are actually an input into the y axis of the TQ to Load tables - so basically through the combo of these tables you are telling the car what load it should target for a certain throttle/RPM value - is that right?

If so, then asking for more load at these closure points should lessen the throttle closures - IF I am understanding how these tables work that is!!


The sawtoothing you are talking about is just the throttle plate cycling open/closed right? I think I saw a good example log of it earlier in this thread when I read through it yesterday.

For the record, I think Alex and Stratified do great work, and continue to recommend them to others - I am just a tinkerer at heart and want to learn!


Thanks

 

[BizarroST]

[MENTION=4189]Xaendeau[/MENTION],
specific to the load to TQ and TQ to load tables, on that log I uploaded, what do you think explains the dip down from ~70 degrees to ~25 degrees ETC angle - when the requested TQ is up at 382, which according to my tables would reflect a load of 3.0, at that point I am sitting at a 2.0 load so wouldn't the ECU attempt to raise the load to meet the requested TQ? Or at that point is it really just the boost limits that are kicking in and causing the plate to close ya think?

Just trying to figure out if I have the 'logic' behind how these all interact correct.

Thanks

 

[Xaendeau]

[MENTION=4189]Xaendeau[/MENTION],
specific to the load to TQ and TQ to load tables, on that log I uploaded, what do you think explains the dip down from ~70 degrees to ~25 degrees ETC angle - when the requested TQ is up at 382, which according to my tables would reflect a load of 3.0, at that point I am sitting at a 2.0 load so wouldn't the ECU attempt to raise the load to meet the requested TQ? Or at that point is it really just the boost limits that are kicking in and causing the plate to close ya think?

Just trying to figure out if I have the 'logic' behind how these all interact correct.

Thanks

It has been over a year (two?) since I looked at that stuff. Currently don't have any functioning software to tune with (and I am having Stratified tune my big turbo), so I am running 100% off of memory. Not going to be any help with anything extremely specific. Just wanted to try and help you get a clearer picture of what is going on. Learning is fun!

Edit: In your previous post, it sounds like you are heading in the right direction, but I don't have access to any tuning software for this platform since they changed the Ford software over at Cobb a while back...when it used to be 100% free. I imagine it is probably better the way the software is right now.

 

[BizarroST]

Thanks No problem - I think I need to go find a nice road this weekend and take me laptop and just try some things out