megasquirt gurus help please - Tuning Forum

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megasquirt gurus help please
Thursday, October 20, 2005 4:49 PM
ok so the new board is in the car and its somewhat working, i can't get the car to start because of some problem.
i used this diagram for wiring


on the main relay i have pin 85 grounded, and i am not getting voltage to the megasquirt board, when that is not grounded i get just under 4.5v to the board. I don't want to try and turn the car over because i'm afraid if that isn't grounded it'll hurt something. I think this is the reason why i am getting a low voltage to burn the chip correctly.

so can anyone help me out




Re: megasquirt gurus help please
Thursday, October 20, 2005 5:06 PM
Where are you testing the voltage you are getting of 4.5 volts?


<a href="http://www.j-body.org/members/mrpute"><img src="http://www.j-bom.com/images/sigs/putesig.jpg">
Re: megasquirt gurus help please
Thursday, October 20, 2005 5:11 PM
Can you hear the relay click when you turn the ignition from on to off? You should be able to hear it clicking open and closed when you charge the coil. Also be sure the relay you have has the same pinouts as the schematic. It should but double check.

Also check the resistance from pin 30 to pin 87. With the ignition on it should read 0 ohms, with the ignition off it should read OL or open or however your meter displays a open circuit.

Hopefully you get it worked out. Once you do, post up some of your settings. I'd love to compair.

Right now i have cranking PW at 7ms
after start enrich at 200%
and no warmup inrichment since theres a problem with my CTS

Good luck!!!


<img src=http://home.comcast.net/~richnj221/smiley.gif>
Re: megasquirt gurus help please
Thursday, October 20, 2005 5:29 PM
the 4.5v/0v is through the real time display on Megatune when the car is on ACC.
I can hear and feel the relay click when the ignition is turned. The relay does have the same pin outs also.



Re: megasquirt gurus help please
Thursday, October 20, 2005 6:18 PM
i think the problem is in my power supply itself. I have the power spliced into the fuel pump. in the megamanual now after thinking about it long and hard it says that the fuel pump is turn on for a short time to allow for start up pressure, then is shut down until the car is turned over. When i have the car on megatune, i get a reading of just under 12v when i first turn the car into ACC. then it goes down to 4.5v when the relay is not ground at pin 85. This part still doesn't make sence to me since i get voltage when not grounded but none when grounded.

Where are you guys getting your power from for megasquirt to give you a full ~12v on ACC and crank



Re: megasquirt gurus help please
Thursday, October 20, 2005 9:46 PM
The main relay should be pulling power directly from the battery just like it's shown in the above picture. Power for the fuel pump should also come directly from the battery just like it's shown in the picture.

The ignition switched 12 volt line should be used to power the switched side of the relays.

This is exactly why I purchased the relay board. It ends confusion and allows you to get wired up pretty quickly.


<a href="http://www.j-body.org/members/mrpute"><img src="http://www.j-bom.com/images/sigs/putesig.jpg">
Re: megasquirt gurus help please
Friday, October 21, 2005 5:52 AM
Being ited into the fuel pump for main power is definately not where you want to be. Like pute said pin 30 of the relay gets tied directly to the battery. Pin 85 will end up being grounded, and tie pin 84 into the ignition power source for the stock ECU. That's one of the few ignition sources that has power during cranking.

I'm not sure why your seeing 4.5 v the way your set up now. If the factory fuel pump is switched on by a solid state device there may be some transiant voltage left in the line that's there until you ground out the circuit??????? Who knows, but move the wires to the right locations and you should be ok.


<img src=http://home.comcast.net/~richnj221/smiley.gif>
Re: megasquirt gurus help please
Friday, October 21, 2005 10:34 AM
alright after reading this I did get it right , but now i'm gettin 12v to ms even with the car off which i know isn't right

here is a picture i made of my wiring,



they only thing wrong with it is that pin 85 on the FP does lead to pin 37 on the Db-37 connector. I didn't see it go there before but i just went out and doubled checked it and it is going to the right place.

Now i have 12v to ms all the time even off, but also the FP turns on only turns on for a second or 2 after the car is turned onto ACC.(according to MS's LED's). The FP is not turning on during cranking, again noticed this by MS LED's that turn on when the FP is turned on.

Also the Injectors are not firing, according to the LEDS once again

but i did get the car to fire, and then die instantly



Re: megasquirt gurus help please
Friday, October 21, 2005 10:39 AM
sorry picture fixed





Re: megasquirt gurus help please
Friday, October 21, 2005 4:45 PM


That's what you want... the reason every thing is on all the time is becasue the relay is on all the time based on the schematic you posted. Pin 84 on both should be tied to an ignition source. A place that is 0 volts when the key is off and 12v when the key is on or cranking

Get that worked out and see how you make out


<img src=http://home.comcast.net/~richnj221/smiley.gif>
Re: megasquirt gurus help please
Friday, October 21, 2005 4:46 PM
ooh yea don't mind the chicken scratch... 5 min drawing while at work

It gets the point across


<img src=http://home.comcast.net/~richnj221/smiley.gif>

Re: megasquirt gurus help please
Monday, October 24, 2005 6:54 PM
thanks for the help. I did get it wired up correctly and everything, and after about 10 mins for trying to get it to fire i found out that the injector fuses were blown, replaced them and it fired up .. it idle wierd i have to get the idle figured out and stuff, but here where it gets wierd. I have it going it stays idling for like 2 mins even though its 40 Degrees out, and i didn;t touch the warm up enrichments. i shut the car down to try and get a better VE table going since i was running super lean in idle then i start it back up again to show my buddy i got it started. it works and such, then i shut it down and then try to burn the VE table and i have no power. Now i can't get power to the MS board again and i can't figure out wire, i've checked all the fuses and connections and can't figure it out, it got really cold so i came inside tomorrow i'm going to try again



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