VR Sensor and No rpm reading - sort of!

For discussing how to choose sensors and create a wiring harness for all Bowling and Grippo versions of the MegaSquirt® EFI controller.
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nevtiger
MegaSquirt Newbie
Posts: 16
Joined: Wed Dec 01, 2004 7:26 am
Location: Andover, UK

VR Sensor and No rpm reading - sort of!

Post by nevtiger »

Ford VR sensor, 36-1 wheel, Microsquirt latest version all running in shadow mode on a carb and dizzyed engine.

When i start the engine and Tuner Studio is in the default state for trigger wheels i get rpm rise and fall as per the engine but with very sill high values - 14k rpm and up.

If i set the trigger wheel to be 36-1 then i get not rpm reading at all.

Is my VR sensor U/S, wired incorrectly? Is there something i am missing?

Nev
Matt Cramer
Super Squirter
Posts: 2951
Joined: Sat Jul 03, 2004 11:35 am

Re: VR Sensor and No rpm reading - sort of!

Post by Matt Cramer »

Could be settings, or it could be the sensor is wired backwards. If swapping the wires doesn't fix it, please post your MSQ and I'll look at the settings.
pluisje
MegaSquirt Newbie
Posts: 11
Joined: Mon Apr 16, 2007 2:22 am

Re: VR Sensor and No rpm reading - sort of!

Post by pluisje »

nevtiger wrote:default state for trigger wheels
the default state is based on a spark-point system,
so 4 or 8 fires every rpm.

when looking at a 36-1 wheel, you will have 35 fires every rpm,
so it isn't a big surprice if you get 35/8 more rpm as supposed.

the problem with no rpm at 36-1 is probably in wrong wiring,
but on a VR-sensor, i have seens a wrong wired VR-sensor sending
out 2x the normal rpm.

first test your settings;
go to Ignition Set-Up/Advanced Ignition Options and fill in;
Trigger Wheel Teeth; 36
Missing Teeth; 1
Skip Teeth; 18
Delay Teeth; 9

this should get you the right rpm, no mather the nr of cilinders.
Spitfire Thuimph
2 lambda probes,
1500 EFI,
quattro cilindri octa valvole,
12 volt 4 wheels and lots of parts driving close together.
nevtiger
MegaSquirt Newbie
Posts: 16
Joined: Wed Dec 01, 2004 7:26 am
Location: Andover, UK

Re: VR Sensor and No rpm reading - sort of!

Post by nevtiger »

I shall try that this evening - thanks.

Nev
nevtiger
MegaSquirt Newbie
Posts: 16
Joined: Wed Dec 01, 2004 7:26 am
Location: Andover, UK

Re: VR Sensor and No rpm reading - sort of!

Post by nevtiger »

I put the settings in as follows:

No of Teeth = 36
Missing teeth = 1
Skip Teeth = 18
Delay teeth = 18 (wheel is 180 out on crank)

Tried with the sensor wired one way and then opposite and with another sensor but still no rpm reading. Checked that there is connection from MS plug to VR plug and i get a loop r of 0.4ohms wich is basically the meter leads.

What am i doing wrong?????
pluisje
MegaSquirt Newbie
Posts: 11
Joined: Mon Apr 16, 2007 2:22 am

Re: VR Sensor and No rpm reading - sort of!

Post by pluisje »

get the sparkplugs out, get the engine starting at contstant rpm
and try to measure the voltage in AC over the VR-sensor.
you can try with sparkplugs, but without your battery will live longer...

if you get 2volt or more, you have a good VR-sensor and triggerwheel,
if not, try another VR-sensor till you have a AC over the sensor at 200-300rpm (starter engine).
1 volt or less will give you starting problems in the winter,
so get a good strong signal.

if you do get 2volt or more,
it will probably be the wiring,
make this 2 connections on your board;
Image

now you can check if you get AC into your board
and a voltage out to the chip with a scoop;
Image

i hoop you don't need the scoop, but this way you will get it running for sure.
Spitfire Thuimph
2 lambda probes,
1500 EFI,
quattro cilindri octa valvole,
12 volt 4 wheels and lots of parts driving close together.
nevtiger
MegaSquirt Newbie
Posts: 16
Joined: Wed Dec 01, 2004 7:26 am
Location: Andover, UK

Re: VR Sensor and No rpm reading - sort of!

Post by nevtiger »

Pluisje,

I chased the voltage from the Sensor and concluded it was a good set up thus concentrated on the Tuning Software.

Finaly found that i had the ignition algorith in Predicted rather than calculated and this then gave me a good rpm!

Then the ECU stopped working and is away being looked at as we speak! Ho hum.
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