ARZ_ Posted February 20, 2007 Share Posted February 20, 2007 Im looking for a boost controller that will control boost differently in each gear. IE: 14psi in 1st gear, 18psi in 2nd, 24psi in 3rd and 28 in 4th and 5th. My trans has a speed sense output. I have an AVCR and the theory is that with a tap into the tach output and a tap into the speed sensor the AVCR can figure out what gear the vehicle is in and support a gear based boost control. The problem is, even with 275 40 17 drag radials the boost comes on so violently that the tires are ripped loose in first, second, and sometimes 3rd gear. If MS could give me a gear based boost that would be the best. Can this be done or can anybody come up with any ideas on how to achieve this? Quote Link to comment Share on other sites More sharing options...
trippintl0 Posted February 20, 2007 Share Posted February 20, 2007 since MS is programmable, if you are good at writing assembly language code, you could probably use an input from a vehicle speed sensor, or better yet, from the tranny output shaft (that way rear end gearing and tires wouldn't affect it), compare that with the RPM of the engine, to determine what gear you are in. For example: if vehicle speed >15 and <20, And RPM's > 3000 then Gear = 1 if gear = 1 then maxboost = 14 psi (etc.) this is theoretical of course, and would have to be set up for each car / transmission. To actually do it, you'd probably have to set it up in the form of a table, using indexes to pull the correct data. It would probably be too slow just to use 'compare/jump' instructions. I imagine the whole thing would be extremely tedious. A possibly much easier way to accomplish the same thing would be to simply divide the vehicle speed by RPM to determine the ratio. Then find the closest ratio to this. Quote Link to comment Share on other sites More sharing options...
gearheadstik Posted February 26, 2007 Share Posted February 26, 2007 Any updates on this? I have just purchased a AEM tru boost controller but might had rather do this if all works out...Which one you think would be better? Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted February 27, 2007 Author Share Posted February 27, 2007 Well.. Today I installed a boost controller.. This picture shoes the FET. -[GATE] Pink wire goes to X4 Gate (connected to source wire using 10k resistor, then a 100ohm resistor inline) -[DRAIN] Black wire goes to X12 (or just run straight to valve. X12 runs out of the DB37 connector on pin 27) -[sOURCE] Blue wire goes to the D1 pin. D1 is a confirmed ground. (I eventually moved this to a fixed ground point on the Megasquirt case and grounded the case to the chassis) Excuse the messy electrical tape. Behind the tape is the resistor inline from the GATE to the SOURCE. This shows the pink wire (GATE) to the X4 pin This shows the blue wire (SOURCE) to the D1 ground pin This shows the black wire (DRAIN) to X12 output ------------------------------------------------ This is how the unit is hooked up - Gate (pin1) goes to X4. I connected it to the "source wire" using a 10K resistor, then after that I installed a 100ohm resistor inline (pink wire) - Drain (pin2) goes directly to the input on the GM fast acting valve. (Rather than connecting the wire to X12 and wiring out of the DB37 I just ran the wire straight to the fast acting valve.) (black wire) - Source (pin3) is grounded to the chassis and MS case. Also has that 10k resistor to the "gate wire" (blue wire) This shows the connector with a "1N4002" diode between the two wires at the plug to filter out voltage spikes. Cathode (bar) goes to the positive. Shows the hook up and hoses. Now I have been messing with the settings like crazy. I have tried all of the Solenoid PWM rate.. ranging from 39hz all the way to 5hz I have the controller update (ms) set to 10ms Proportional Gain % - I have tried from 50% to 90% no luck Differential gain I tried the default 9.8 and then even dropped to 0. Increase voltage = Increase boost (i want to run open loop with the boost duty target table) Now on my boost duty target table.. I have tried as low as 20 and as high as 90 all the way across the board.. Nothing. I can hear the GM fast acting valve working and ticking.. and when I rev the engine and quickly ground the Fast acting valve the valve opens up and I can hear air venting. My wastegate is factory set at 6psi.. I used a manual boost controller and had it set to 15psi. WHY oh WHY can't I get this setup to work?! the X4 output is selected to boost control and under boost the "output 1/boost control" turns green on Megatune.. so I know its sending a signal. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted February 27, 2007 Author Share Posted February 27, 2007 By the way once I get this thing working properly.. I will be posting pictures and the cure to my problem Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted February 27, 2007 Author Share Posted February 27, 2007 after thinking long and hard... ive concluded that the valve is stuck OPEN right now and allowing the boost to open the wastegate .. which allows me to run stock boost (6psi) I tested the unit by blowing in it with the GM Valve with a loose ground.. and I could blow through the valve and feel the air out the other side. Once I attached the ground.. the valve closed which is good. I take off the ground and it opens back up. Sooo.. that means that the valve is not grounding.. and the valve's ground leads to the DRAIN pin on the FET. ** Does the SOURCE (ground) of the FET have to be grounded to the Megasquirt unit or can I ground it to the chassis?! ** Does the voltage coming out of the X4 output on the Megasquirt unit close the connection between the Gate and Drain, which causes the grounding?! Quote Link to comment Share on other sites More sharing options...
z-ya Posted February 27, 2007 Share Posted February 27, 2007 Hear is the schematic for the fast acting valve: ** Does the SOURCE (ground) of the FET have to be grounded to the Megasquirt unit or can I ground it to the chassis?! They should be one in the same. Where do you have the FET circuit? Is it in another case outside of the MS? Is it in the MS? ** Does the voltage coming out of the X4 output on the Megasquirt unit close the connection between the Gate and Drain, which causes the grounding?! When Pin X4 goes high, it turns on the FET. The makes the connection between the drain and source a low resistance, thus providing a ground path for the valve. But X4 is not simply turned on, it is pulse width modulated at some rate to modulate the fast acting valve. So to know for sure if it is working, you need to scope it. I would double check all of you wiring with an Ohm meter to be sure everything is connected right for starters. If I get a chance I will hook up my test MS and see if I can see what the X4 output does when boost control is enabled. What version of code are you using? Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted February 27, 2007 Author Share Posted February 27, 2007 Funny... I attached the FET to a piece of plastic.. and the FET has a metal backing.. maybe it needs to be grounded .. LoL Now the FET is grounded and now the valve is closed.. neat.. but now its STUCK CLOSED and I am overboosting.. I have the boost table set to ZERO! and its still closed! WTF Pete I am running 021s right now.. I've checked the wiring about 20 times and I can't figure this out.. grrr! Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted February 27, 2007 Share Posted February 27, 2007 Maybe that's the "experimental" part of this code. Your code is way outdated now, maybe try updating it to the newer firmware and MT. Good luck! I wanna get this to throw on my ZXT! Mario Quote Link to comment Share on other sites More sharing options...
z-ya Posted February 27, 2007 Share Posted February 27, 2007 Before you ground the tab on the FET, check the datasheet to be sure that the tab is connected to the source (S). Otherwise it might be time to order up another FET. Quote Link to comment Share on other sites More sharing options...
Guest TeamNissan Posted February 27, 2007 Share Posted February 27, 2007 Just want to thank you guys for sorting this out since I'll be following in your foot steps soon lol. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted February 27, 2007 Author Share Posted February 27, 2007 http://www.irf.com/product-info/datasheets/data/irlz44n.pdf This is the data sheet .. any electrical guru's out there?! Is the metal mounting tab connected to the (S) Source pin?! Quote Link to comment Share on other sites More sharing options...
woldson Posted February 27, 2007 Share Posted February 27, 2007 no it is drain as pin 2 Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted February 27, 2007 Author Share Posted February 27, 2007 soo the mounting tab should be grounded.. and is connected to the DRAIN?! that doesnt make sense... because Megasquirt is supposed to ground the valve.. closing the ground closes the valve. an open ground opens the valve. But if the drain is grounded to the Megasquirt unit through the metal mounting tab.. than the drain is always grounded.. and Megasquirt is not controlling the ground. Quote Link to comment Share on other sites More sharing options...
datman Posted February 27, 2007 Share Posted February 27, 2007 You can mount the FET with an insulator to stop it shorting the drain output to ground. Connect pin 3 (source) to ground, pin 2 (drain) to the valve and pin 1(gate) to the output from the MS. Quote Link to comment Share on other sites More sharing options...
z-ya Posted February 27, 2007 Share Posted February 27, 2007 Just want to thank you guys for sorting this out since I'll be following in your foot steps soon lol. You are assuming that we will get it all sorted out Quote Link to comment Share on other sites More sharing options...
Guest TeamNissan Posted February 27, 2007 Share Posted February 27, 2007 I have confidence in you guys lol Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted February 28, 2007 Author Share Posted February 28, 2007 Ok.. I learned that the mounting tab.. connects to the DRAIN tab.. so DO NOT MOUNT THE FET TO METAL or use a metal screw! The point of MS is to close the signal and create a ground for the DRAIN. Closing the drain closes the valve. If you ground the tab, the drain is closed, so the valve is closed, which closes the wastegate, which results in overboosting. Now to get the damn thing running properly and work with my tables Quote Link to comment Share on other sites More sharing options...
z-ya Posted February 28, 2007 Share Posted February 28, 2007 I don't see anywhere in that datasheet where it shows the physical pin assignments for the IRLZ44N TO220 package. Anyone else? Quote Link to comment Share on other sites More sharing options...
datman Posted February 28, 2007 Share Posted February 28, 2007 Z-ya, look at the last page of the pdf...page 8, top right image shows pin numbers 1 to 4 4 being case. I must admit they could have made it far easier by showing pin numbers on the top page. Quote Link to comment Share on other sites More sharing options...
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