Megasquirt Last questions for building ECU
Thread Starter
Joined: Sep 2006
Posts: 3,054
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From: Goose Creek, SC
Last questions for building ECU
Ok, 1 last bank of questions now that I've (almost) completed the ECU. That doesn't mean I won't have more when i go to wire it in the car though 
I posted this in my last thread, but I don't think anyone's looking there anymore...
Once again, MS2, V3. Like I mentioned before, i'm using the Zeal Daughterboard. The DIYAutotune instructions say to leave out R19, Q4, Q20, R39, & D8. OK, easy enough. Says we'll run the IAC from the daughterboard.
Do I need to do anything with step 65? I'm pretty sure that doesn't apply to the FC ignition, but I'm just double-checking. It did say
Jumper it, or no? I didn't do anything with step 65 yet (mostly didn't understand my options) so I skipped ahead to step 66.
I completed step 69 where it says that you *can* if you choose to build the PWM flyback damping circuit. Says no problem either way, but I have low impedance injectors, so I THINK I'm good here.
Also, I did step 71... should I have? It said it was recommended to most people....
And finally, step 74. I omitted R39, but do I still need to install that jumper, or omit it as well for the daughtercard?
I hope one I can get this cleared up soon, I really want to drive the FC again
I posted this in my last thread, but I don't think anyone's looking there anymore...
Once again, MS2, V3. Like I mentioned before, i'm using the Zeal Daughterboard. The DIYAutotune instructions say to leave out R19, Q4, Q20, R39, & D8. OK, easy enough. Says we'll run the IAC from the daughterboard.
Do I need to do anything with step 65? I'm pretty sure that doesn't apply to the FC ignition, but I'm just double-checking. It did say
If you are not using the IGBT high current driver circuit, but want to use the MegaSquirt-II output to control an ignition module (7 or 8 pin HEI for example), jumper JS10 to IGN to bring the signal out on DB37 pin #36. You do not need a pull up, the processor port has one enabled already (at 5 Volts). Skip ahead to step #66
I completed step 69 where it says that you *can* if you choose to build the PWM flyback damping circuit. Says no problem either way, but I have low impedance injectors, so I THINK I'm good here.
Also, I did step 71... should I have? It said it was recommended to most people....
And finally, step 74. I omitted R39, but do I still need to install that jumper, or omit it as well for the daughtercard?
I hope one I can get this cleared up soon, I really want to drive the FC again
Thread Starter
Joined: Sep 2006
Posts: 3,054
Likes: 2
From: Goose Creek, SC
65. It is choice time again. In this case, you will decide whether to populate the high-current ignition driver circuit. This circuit can be used to drive a single coil in a distributor application. In conjunction with an appropriate input signal (from a VR, Hall, or optical sensor, or even points), it allows you to eliminate a separate ignition module, such as a GM HEI 7 or 8 pin module, and run the coil directly from MegaSquirt.
[then there's a bunch of other stuff about the actual installation of the components]
If you are not using the IGBT high current driver circuit, but want to use the MegaSquirt-II output to control an ignition module (7 or 8 pin HEI for example), jumper JS10 to IGN to bring the signal out on DB37 pin #36. You do not need a pull up, the processor port has one enabled already (at 5 Volts). Skip ahead to step #66.
Like I said, I haven't done anything with step 65 YET.
I'm ok with step 69. I'm running low impedance injectors, so we're all good here.
71. It is choice time yet again. You have to decide whether to install the current limit circuit for driver FET protection. This clamps the current to ~14 Amps, and it is recommended that most people install this. To install the current limit protect circuit:
I did it, and I'm pretty sure I was supposed to, but I still want to double-check.
OOPs, not step 74, it was 75.
75.Install R39 and R40 {1.0H-ND, 1 Ohm, brown-black-gold}. These are located on either side of the transistors (Q19 & Q20) that you installed in the last step. (Note - if you are using a PWM idle valve, install a jumper in place of R39).
Like I said, I omitted r39, but didn't install the jumper yet. Yes, no?
[then there's a bunch of other stuff about the actual installation of the components]
If you are not using the IGBT high current driver circuit, but want to use the MegaSquirt-II output to control an ignition module (7 or 8 pin HEI for example), jumper JS10 to IGN to bring the signal out on DB37 pin #36. You do not need a pull up, the processor port has one enabled already (at 5 Volts). Skip ahead to step #66.
Like I said, I haven't done anything with step 65 YET.
I'm ok with step 69. I'm running low impedance injectors, so we're all good here.
71. It is choice time yet again. You have to decide whether to install the current limit circuit for driver FET protection. This clamps the current to ~14 Amps, and it is recommended that most people install this. To install the current limit protect circuit:
I did it, and I'm pretty sure I was supposed to, but I still want to double-check.
OOPs, not step 74, it was 75.
75.Install R39 and R40 {1.0H-ND, 1 Ohm, brown-black-gold}. These are located on either side of the transistors (Q19 & Q20) that you installed in the last step. (Note - if you are using a PWM idle valve, install a jumper in place of R39).
Like I said, I omitted r39, but didn't install the jumper yet. Yes, no?
MegaSquirt Mod
Joined: Sep 2004
Posts: 4,721
Likes: 1
From: Maryland
65. It is choice time again. In this case, you will decide whether to populate the high-current ignition driver circuit. This circuit can be used to drive a single coil in a distributor application. In conjunction with an appropriate input signal (from a VR, Hall, or optical sensor, or even points), it allows you to eliminate a separate ignition module, such as a GM HEI 7 or 8 pin module, and run the coil directly from MegaSquirt.
[then there's a bunch of other stuff about the actual installation of the components]
If you are not using the IGBT high current driver circuit, but want to use the MegaSquirt-II output to control an ignition module (7 or 8 pin HEI for example), jumper JS10 to IGN to bring the signal out on DB37 pin #36. You do not need a pull up, the processor port has one enabled already (at 5 Volts). Skip ahead to step #66.
Like I said, I haven't done anything with step 65 YET.
[then there's a bunch of other stuff about the actual installation of the components]
If you are not using the IGBT high current driver circuit, but want to use the MegaSquirt-II output to control an ignition module (7 or 8 pin HEI for example), jumper JS10 to IGN to bring the signal out on DB37 pin #36. You do not need a pull up, the processor port has one enabled already (at 5 Volts). Skip ahead to step #66.
Like I said, I haven't done anything with step 65 YET.
I'm ok with step 69. I'm running low impedance injectors, so we're all good here.
71. It is choice time yet again. You have to decide whether to install the current limit circuit for driver FET protection. This clamps the current to ~14 Amps, and it is recommended that most people install this. To install the current limit protect circuit:
I did it, and I'm pretty sure I was supposed to, but I still want to double-check.
I did it, and I'm pretty sure I was supposed to, but I still want to double-check.
OOPs, not step 74, it was 75.
75.Install R39 and R40 {1.0H-ND, 1 Ohm, brown-black-gold}. These are located on either side of the transistors (Q19 & Q20) that you installed in the last step. (Note - if you are using a PWM idle valve, install a jumper in place of R39).
Like I said, I omitted r39, but didn't install the jumper yet. Yes, no?
75.Install R39 and R40 {1.0H-ND, 1 Ohm, brown-black-gold}. These are located on either side of the transistors (Q19 & Q20) that you installed in the last step. (Note - if you are using a PWM idle valve, install a jumper in place of R39).
Like I said, I omitted r39, but didn't install the jumper yet. Yes, no?
Ken
Thread Starter
Joined: Sep 2006
Posts: 3,054
Likes: 2
From: Goose Creek, SC
No jumper needed. Got it!
Directly running low impedance injectors (550 pri, 720 sec), no resistor pack. I DO have a bank of 10ohm (big fat ceramic ones, I forgot what power rating they were, but it was relatively high) resistors, but since I went with the flyback damping circuit, I'm not going to be using them.
And I am running the stock BAC. It's in good working condition, and I'd hate to have to keep tweaking settings or have a retarded high idle in order to eliminate it. Keep in mind though, I am using the zeal daughtercard, which has the built-in driver for the pwm idle air controller.... that's what the DIY autotune instructions say.
So will installing that jumper interfere with the operation of the driver on the zeal engineering daughtercard?
Directly running low impedance injectors (550 pri, 720 sec), no resistor pack. I DO have a bank of 10ohm (big fat ceramic ones, I forgot what power rating they were, but it was relatively high) resistors, but since I went with the flyback damping circuit, I'm not going to be using them.
And I am running the stock BAC. It's in good working condition, and I'd hate to have to keep tweaking settings or have a retarded high idle in order to eliminate it. Keep in mind though, I am using the zeal daughtercard, which has the built-in driver for the pwm idle air controller.... that's what the DIY autotune instructions say.
•When building the IAC circuit, omit R19, Q4, Q20, R39, and D8. You'll use the driver on the daughter card instead.
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