Testing the Megasquirt II during installation. please HELP!

[bubbajoe13]

So I'm assembling an MS II with 3.0 PCB... tested the serial and power circuits and everything was fine. Using TunerStudio MS for mac.
I'm having trouble testing that the TunerStudio shows the sensor adjustment on the Stimulator. I'm following the installation manual as well as using the mods to use the MSII on a 5.0 mustang motor from the 80's. (steps are show at the end of my post)

So here's the problem I'm having:
-RPM - doesnt work, however i havent installed the 1K resistor for the D2 Diode, so I've read that the RPM wont work
-O2 - does adjust by power cycling the Stimulator and checking to see if the gauges vary
-CLT - does adjust but only on the very end (or beginning) of the Pentiometers travel and then shows eratic output
-TPS - doesnt work
-IAT - does adjust but same as CLT

Battery is 8.87 volts. and I havent installed the MAP Sensor yet (didn't receive it in my kit somehow).

ANY HELP WOULD BE AMAZING, thank you!!!


Using the MegaSquirt-II PCBv3 with the factory TFI Ignition (such as the 86-95 Mustang)

If you're assembling your MegaSquirt-II from a kit (Part# MS230-K):

For the most part, stick with the standard assembly documentation at http://www.megamanual.com/ms2/V3assemble.htm. I'll just be covering any differentiation from that doc here.

Step 22: You really don't need any of the 5 jumper wires listed in this step. If you ever use this ECU on a different car that does use a stepper motor IAC you can add them then. Personally, I'd leave them out for your Mustang as you can use the IAC outputs for other cool stuff later.

Step 50: You'll be installing the 'Hall/Optical Input Circuit' (currently all steps under 50a). If you see any steps that say 'only do this if you are triggering from the negative terminal of the coil', you aren't, so don't. ;)

INSTEAD OF JUMPERING D2 as directed here, install a 1k 1/4watt resistor in it's place.

Step 51: You don't need these components, but I'd recommend installing them anyways in case the MS ECU is ever used on another car with a VR sensor.

Step 52: Set the jumpers for Hall/Optical/Points. That would be XG1 to XG2, OPTOIN to TACHSELECT, and TSEL to OPTOOUT.

Step 59: You will be doing the PWM Idle Mod using the parts from the mk-PWMIAC. That means you leave D8 out when you get to this step.

Step 62: Follow the steps in the blue box following step 62 to finish installing the mk-PWMIAC for control of your 2-wire idle valve.

Step 65: You ARE USING THE IGBT High Current Ignition Driver Circuit. That means you complete step 65. Install everything just as this step directs you to (which does mean no R57), and install the jumpers to enable the circuit. (IGBTIN to JS10 and IGBTOUT to IGN) Note that if you are using a metal backed transistor like a BIP373 or certain switching transistors, you must use a mica insulator under Q16.

NOTE-- there was originally an error in the MS2 TFI docs that said to leave R43 out for this setup, I've found that to be incorrect and it's been corrected it in the MS2 docs, so LEAVE R43 in!

Step 69: Choice time -- Install the PWM Flyback Circuit bits....

Step 71: Choice time -- Install the current limit circuit for FET protection....

Step 74: Do not install Q20 (part of the mk-PWMIAC mod)

Step 75: Leave R39 out and jumper it instead (part of the mk-PWMIAC mod)
Now for the final step (Mod for TFI Ignition Output). Use a 100ohm, 1/4watt resistor. Solder one leg of this to the IGN/IGBTOUT jumper wire. Solder the other leg of this to the hole labeled S12. (Not to be confused with the hole labeled S12C !) The S12 label is on TOP of the board, but you'll place this resistor on the bottom generally. Check out this diagram.

[Matt Cramer]

What Stim version do you have? The temperature pots may behave like that pretty often with Ford sensor calibrations, but I'm concerned on the lack of RPM.

[bubbajoe13]

I'm using the MegaSquirt Stimulator v2.2.
Im pretty sure the RPM shouldnt work because i've yet to jumper (or install the resistor per the instructions for modifying the MSII to be used with a Ford Mustang TFI) where D2 is supposed to sit.
I'm happy to hear about the temperature ports behaving as such, but what about the TPS? im getting absolutely no response anywhere from it. Any ideas?

[Matt Cramer]

If D2 is empty, you won't get RPM.

Check to see if the voltage from the TPS is making it to the CPU pin.

[bubbajoe13]

How do that? (Test the voltage)

[trakkies]

Measure between pin22 on the DB37 and ground. That should vary from approx 0 - 5v as you open the throttle.

[bubbajoe13]

ok i tested between pin 22 (the tps in from the stimulator) and the ground (which i chose pin 19 or 18 as they are both sensor grounds) and with it all the way open/closed one way (i don't know which it is on the stimulator) i measured 4.308v and when i turn the knob all the way to the other extreme open/closed, i measured 4.340v. so it does vary, but extremely small and not over the full 0-5v range.
any help would be amazing.

Thank you and sorry for the huge delay with posting. Life gets in the way sometimes.

[Matt Cramer]

I would check to be sure the TPS pot has a solid solder joint to ground first.

[bubbajoe13]

i checked the resistance from POT ground to pin 7-8-9-10 and got 95 ohms (which is what the schematic says [100ohm] should be for the V2.21stimulator). any other ideas? i checked all the diodes ive installed so far (checking for direction), the resistors, and i played with the VR pots (turning them from full counterclockwise to other settings)..but nothing seems to give me a TPS reading.

I'm currently trying to re-flash the firmware, in case for it has corrupted for some crazy reason. But any help would be greatly appreciated.

Thanks for the replies so far!

[Matt Cramer]

Check the resistance from the TPS pin to ground with the trim pot at both extremes of its travel and the Stim not powered up What do you find?

[bubbajoe13]

100 ohms and 67.5 K measuring between pin 10 and pin 22.

[bubbajoe13]

Any ideas? Anyone?

[Matt Cramer]

That should be OK. Does it have a good ground?

[bubbajoe13]

Ground is good.

[trakkies]

To check the entire circuit, measure volts between AD3 (pin 26) on the daughter card and ground. It should vary from approx 0-5 volts with the TPS pot.

[bubbajoe13]

Ya, the voltage Does vary from 0-5v. Does that mean the daughtercard is bad? If so, is there a way to verify it?

[trakkies]

2 years later?

Have you checked if Tuner Studio gets a value at minimum and maximum for the TPS? (Tools - calibrate TPS) That would show if the processor is seeing the TPS circuit.

[bubbajoe13]

haha..

i checked the min and max, and the processor isn't seeing the min value (or any other value than one). no matter what position the POT is in, it shows 1023.

[trakkies]

I'd fist try re-loading the code. If you can, use a decent 12v supply to do this. I've had problems loading code due to a poor power supply. A fully charged car battery is fine - but do use a 1 amp fuse to protect the MS in event of an accident.

[bubbajoe13]

I reloaded the code and I didn't have any luck receiving a different value for the TPS calibration. I AM, however, using a 9v battery (the board hasn't been fully built/soldered and I'm using the Megastim battery hook up).