Help identifying Hyundai crank sensor

[Bubba Zanetti]

Hi,

My name is Velibor, and I am new to this forum - I have some problems with Hyundai Accent and can't find unfortunately any info on the web.


This is the story :

I recently installed Megasquirt in Hyundai Accent with Coupe 2.0 16V engine swap.

Car started immediately but I have some strange problems with ignition input - car want rev past 2500 RPM no matter what I do

After little investigation it seems that problem is with crank position sensor output that doesn't work well with MS ignition input that I enabled (VR input btw).


Too cut a long story :

Crank sensor has 3-wire connector, and when measuring resistance between pins I get over 1Mohm in any combination - so it isn't standard variable reluctance sensor - but I wan't to be sure, this is the pic of the sensor:

http://img.photobucket.com/albums/v3...ank_sensor.jpg

It has permanenet magnet though, but why can't I measure coil resistance ?

Anybody has a clue what type of sensor is this?


Tnx in advance,
Velibor

[thegrim]

its a hall effects type sensor, i think thats how its spelled anyway.

[Bubba Zanetti]

2 thegrim:

Sorry, I'm not really sure what do you exactly meaned by that - you probably think hall effect sensor?

[mike626t]

What year is your engine?

Anyway, measure the voltage on the pin of the connector (ecu side ) with the key on/engine off. If your sensor is a Hall effect, you will have the following : one 12v, one 5v and one ground. If you have a balanced magnetic sensor (VR) you will have 2 wires going to the ecu and the third will be for the shield (grounded).

hope this helps!

[xxl_05]

hey dude....i had a similar prob with mine..it wouldnt rev past 4000rpm.i fixed it by looking at the positioning of it...apparently the way it is positioned affects the readings of the sensor.wen u hit teh max rpm in ur car does teh car backfire or jus jerk?

[Bubba Zanetti]

2 mike626t:

Unfortunately I don't know exact engine year - in fact, I've had to little time too check many things on that car, including such simple thing

But I've of course measured voltage on all 3 pins and I've got +12V on one pin, ground on second pin, and third pin gave nothing...all that was measured when engine was off, key contact was on.

I even scoped sensor output on idle and it gave me some strange, triangle shaped waveform - Hall effect sensor should give uniform square output , so I thought "OK, it's maybe VR sensor - it has permanent magnet inside afterall".


But when I measured all pin combination(as I mentioned before) I couldn't find reasonable coil resistance (400 - 1500 ohm) - so it isn't VR sensor, at least not some usual type.

If it isn't Hall effect, and if it isn't VR sensor - on which principle does it work?




2 xxl_05:

Interesting thought, but I can't understand how could be possible to move that sensor to another position - it's crank position sensor that is mounted in engine block, and reads 60-2 wheel that's inside engine block - an engine block has only one hole for sensor and another smaller threaded hole for bolt that holds sensor - it's impossible to move it to another position without some serious mods.

You had oem Hyundai ECU or also had MS installed when that happened to your car?

This car backfires very ,very badly when it hits "magic wall" at 2500 RPM - car was (and still is) in dyno shop , so I didn't test drive it yet - but I suppose it's totaly useless to drive it untill I solve " 2500 RPM " problem.


2 ALL:

Please forgive me about my boring and un-creative questions - but I'm totally, totally without ideas, literally exhausted from constant searching over web past few weeks for some meaningful Hyundai sensor info - tnx all for help

[mike626t]

If you have "some weird triangle shape" it's a VR sensor. The shape is called a Sine wave, it should switch between positive and negative voltage and the shape looks exactly like a wave. Those sensor are affected a lot by their distance from the teeth of the wheel. If it's too far from the teeth the voltage will be too low for the ecu to actually see it.

Also check with the scope if the voltage peaks higher (both + and - peak) as rpm increases, if it does then you definately have a VR sensor.

[Bubba Zanetti]

2 mike626t:

Sorry , I wasn't very clear with that - I know how standard VR sensor sine wave waveform look like - it has of course positive & negative half-periode , with amplitude that increases with RPM ...

Or shortly & more understandably , it will look like this:

http://www.picotech.com/auto/wavefor...ve_running.png

Well this sensor has different waveform on output - triangle shaped and only positive (!), without swinging to negative...and what's funny, it doesn't increases with RPM - amplitude stays the same.

Is it possible that this sensor type has some tiny electronic conditioning circuit inside, to filter AC signal from coil , remove negative half-periode and bring triangle shaped output with constant amplitude that doesn't vary with RPM ?

[mike626t]

If it's only positive is has to be either a Hall effect or optical sensor. Anyway with either one you would have a square wave. Just a tough, but i've seen some strange wave shape on scope that were'nt fast enough (sampling speed too slow). Maybe you could backprobe the signal and check the reading by slowly turning the crank manually to see the signal switch between the high and low point. if it's a hall or optical sensor you should suddenly switch from 0v to 5v or the other way around. By turning it slowly the sampling speed does'nt affect the reading.

It would really help if you could give us the year/model of the engine or the wiring diagram.

[Bubba Zanetti]

2 mike626t:

Optical must be totaly out of question - sensor is totaly closed, with permanent magnet inside and it reads 60-2 wheel mounted inside block.

When scoping voltage on sensor output , it was very low - much lower then 5V, I think even under 1V - which should be immposible for normal Hall sensor.

I found some ECU schematics - in fact I found schematic that should be correct for that Coupe engine , please go to this link:

MSx/Extra EFI :: View topic - Hyundai 2.0 coupe ignition problems

This is thread on Msefi.com where I presented my problem with some more details and complete story , and I put some links & schematics (that were very hard to find btw).