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-   -   Cant get rpm on crank with ms3pro? (

smurfbus 08-04-2017 06:17 AM

Cant get rpm while cranking : ms3pro fuel only.
Totally noob on EFI but heres the situation. ground from starter bolt at this time and ms3 wired via relay like their instructions show. fuel pump and injectors relayed too but closed at this time before I get RPM.

Trying fuel only setting with MSD6A and my electrical distributor and RESISTORLESS plugs. So I tried MSD grey or brown tach out to MS3 shielded white VR line CKP+ like instructions say.
No rpm on tunerstudio or stock gauge. Earlier the stock gauge worked from this MSD tach out IIRC. I dont have o-scope so cant measure msd tach out.

Then I tried my Ford VR sensor with the shielded CKP+white and ckp- black and even tried the provided 10kohm resistor paraller, still no rpm on startup on tunerstudio but about double/triple on stock gauge from ms3 tach out. Also tried polarity swap. the vr line shield is cut at 10in from ms3 but that should not block all data.

Tunerstudio tooth logger does not show anything either?

What am I missing here? I can still try the electrical distributor POINTs type trigger but I would not run without MSD so why try.

Tunerstudio connects (but cuts after voltage gets low on startup) and gauges work for tps,map,iat and coolant. possibly WB too at least it shows 20.9 now.

smurfbus 08-04-2017 11:35 AM

Vref has 5 volts so ms3pro fuses are ok. Changed the grounds to battery negative, no help.

Vr sensor is pretty close to 36-1 wheel already but a bit tilted so the leading edge of tooth is closer to sensor. Does this matter? I could try to grind the mount for more level fit.

turbobrat930 08-04-2017 12:00 PM

So, are you saying that you have the engine running, but you are just having problems getting a signal to your tach from the crank? OR, is the engine not running at all?

Here is the O-scope I have and I LOVE it!!! The company is based over there in Europe, so it should be easy for you to obtain.

PicoScope 2205A 25MHz 2-Ch Oscilloscope (PP907) ($225.00) : Saelig Online Store

smurfbus 08-04-2017 12:17 PM

Havent tried starting as there is no rpm so I dont think it would even start? By crank I mean cranking the engine. Ms3 instruction tell to first get good rpm signal and after that add relay for pump and injectors.

That scope look nice and even has sw for linux too which most of them dont. Getting one takes time so I hope to figure this one without a scope.

turbobrat930 08-04-2017 12:23 PM

is your crank pos sensor a reluctor or hall effect? You can verify a signal on either by using a LED, wired to test leads. A reluctor would have a weaker light, as it is depending on the strength of the magnetic field to get its signal from. The hall effect would have power ( +8v to 14v) supplied to it, so it would be easier to see.

Is the sensor face, centered over the tops of the teeth on the trigger wheel? ( not too much left or right) What is the air gap you are running between the sensor face and the trigger wheel? What is the specification on your particular sensor in reference to air gap?

Here is a write-up on using the LED to test, instead of an O-scope

smurfbus 08-04-2017 12:52 PM

Its a reluctor from some ford, dont have any specs but its from gsf. Its lined in the middle of the tooths jst a bit tilted. I tried different gaps but can adjust it even closer.

I will learn about the led stuff, thanks for the tip.

Im thinking it might be tunerstuio or wiring related as even msd tach out did not work.

turbobrat930 08-04-2017 01:04 PM


Originally Posted by smurfbus (Post 9688527)
Its a reluctor from some ford, dont have any specs but its from gsf. Its lined in the middle of the tooths jst a bit tilted. I tried different gaps but can adjust it even closer.

I will learn about the led stuff, thanks for the tip.

Im thinking it might be tunerstuio or wiring related as even msd tach out did not work.

I would not have the sensor tilted to either side. Completely parallel to the top of the teeth. It relies on the leading edge and trailing edge of the passing tooth for the signal. Air gap plays a BIG part in it. Too far away, and you get trigger errors by missing the teeth. Too close, and the sensor could possibly count the trigger wheel as one, long ass tooth!

You absolutely need to make certain you are getting a good signal from the sensor, (or at least on my ecu), the ecu will not fire the injectors or the plugs.

Does your ECU have a run time value menu that you can watch real time while cranking the engine over? I can look on mine and watch both the crank and the cam position sensors, real time (and also get trigger errors real time on both). Just trying to think outside of the box, or at least think of something that you might not have. Hope I have helped some ;)

smurfbus 08-04-2017 01:32 PM

The real time tooth logger has nothing to show and it should show graphig bars for tooths. I really need some out of the box thinking here so thanks

smurfbus 08-04-2017 02:18 PM

It seems the led test is to figure out correct polarity. Its easy to do with ms3 as it has sw options for it and then I have switchable connectors too on hte wires. Rpm should register with both polarities but the other is much better for uniform signal.

I will try to grind the mount for level pickup point.

I tried a normal bulb for the msd tach out but it did not light up at all.

Does anyone know if rpm is required for start up? Some questimates for idle fueling via tps ound possible.

dap930 08-04-2017 02:46 PM

Yes, you have to have a RPM signal before MS will synch and start the sequence of events to start the engine. One being after an RPM signal is sensed the fuel pump relay is energized to run the fuel pumps. I sue that relay to trigger relays for injector power, coil power, WBO power, etc. Are you using "toothed wheel" setting, rising edge for input capture, correct missing tooth angle in TS? I would think you would see some sort of signal in the composite tooth logger unless the vr sensor is bad or some setting is wrong.

smurfbus 08-04-2017 10:17 PM

TS is now st up with 36-1 set for rising, toothed wheel, 66 degrees like gsf said to use.

Will try composite next. Earlier I tryed the first choice, cant remember name, maybe tooth?

With msd tach out I had fuel only setting on TS.

I need to check my battery grounding as my voltage gauge shows about 8 volts soon after cranking it. Its a small lithium battery but cranks really good, only the volts get too low for ms3? I found one thread on msextra where someone had similar problems but could get rpm if feeding ms3 separate battery power so it does not get the low voltage from cranking but that case was never solved. Thats why I have to see if better voltage is the cure.

smurfbus 08-05-2017 06:44 AM

FOUND the problem. My MS3 ign12V went to zero when cranking! So I installed back my starter buttons, one in the console and the other at the rear fuse panel. Now I have bars on the tooth logger but the high bars are not that high compared to the low ones. Hopefully its just VR signal weakness. I have the gap at 30thousand/0.75mm which should be good enough.

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