VEMS Community Forum

Technical => Wiring & Sensors => Topic started by: ranz on May 15, 2010, 04:22:47 AM

Title: RPM (engine speed) input - to what pin?
Post by: ranz on May 15, 2010, 04:22:47 AM
I´m building my own wiring harness and now when I was about to connect RPM to ECU, I don´t find to what pin to connect it?
The car is Audi S2 with 20VT engine.
I´m using standard VEMS ECU because I want to use my car with distributor, at first anyway :P
So what pin?
Title: Re: RPM input - to what pin?
Post by: gunni on May 16, 2010, 02:12:47 AM
http://www.vems.hu/wiki/index.php?page=MembersPage%2FPhatBob%2FUserGuide

Use this guide for your wiring
Title: Re: RPM input - to what pin?
Post by: ranz on May 16, 2010, 04:34:24 AM
Quote from: gunni on May 16, 2010, 02:12:47 AM
http://www.vems.hu/wiki/index.php?page=MembersPage%2FPhatBob%2FUserGuide

Use this guide for your wiring
Is it just me or what? but I can not finde the RPM input pin?
I use the same guide for it... but there are only VR, hall, and other sensor inputs, but no RPM sensor input.
Title: Re: RPM input - to what pin?
Post by: [email protected] on May 16, 2010, 05:50:36 PM
I guess a lot is lost in translation, searching on Rev Counter (what we call them in the UK)
heres a couple of suggestions
http://195.159.109.134/vemsuk/forum/index.php/topic,1090.0.html
http://195.159.109.134/vemsuk/forum/index.php/topic,191.0.html
Title: Re: RPM input - to what pin?
Post by: mattias on May 16, 2010, 06:25:13 PM
Key words : "primary trigger"
Title: Re: RPM input - to what pin?
Post by: ranz on May 16, 2010, 08:46:13 PM
Quote from: mattias on May 16, 2010, 06:25:13 PM
Key words : "primary trigger"
Primary trigger is the sensor next to RPM (rev counter) sensor, and the primary trigger is already connected. But where to connect the other sensor? or does it even need it?


Rob, S2 gets tacho signal from ecu, so I have no wire from sensor to tacho from where to take the signal. Right now I have connected the RPM signal from ecu to tacho from P259 ch0, but from where gets the ECU the engine speed?
Title: Re: RPM (engine speed) input - to what pin?
Post by: mattias on May 16, 2010, 09:25:42 PM
The ECU gets the engine speed from the primary trigger.

Are you sure the "RPM sensor" you are referring to is not an RPM output to signal the gauge in the gauge cluster?
Title: Re: RPM (engine speed) input - to what pin?
Post by: ranz on May 16, 2010, 11:09:08 PM
Quote from: mattias on May 16, 2010, 09:25:42 PM
The ECU gets the engine speed from the primary trigger.

Are you sure the "RPM sensor" you are referring to is not an RPM output to signal the gauge in the gauge cluster?

Yes, I´m sure, see this picture of 3B sensors and stuff:
http://www.s2central.net/images/3B_ECU_Schematic.jpg
From left bottom, there is oxygen sensor, air mass sensor, reference sensor and engine speed sensor.
Top right there is output to tachometer.
Title: Re: RPM (engine speed) input - to what pin?
Post by: gunni on May 16, 2010, 11:56:22 PM
Engine speed sensor will be the VR/Hall sensor.
i.e Trigger input.
Title: Re: RPM (engine speed) input - to what pin?
Post by: ranz on May 17, 2010, 02:34:25 AM
Quote from: gunni on May 16, 2010, 11:56:22 PM
Engine speed sensor will be the VR/Hall sensor.
i.e Trigger input.
But there is already also a hall sensor witch is connected to secondary trigger input.
Primary triger is the reference sensor
Secondary trigger is the hall sensor

Thats why this topic was made... I have all other inputs located, but i do not know where to connect the engine speed sensor :P
Title: Re: RPM (engine speed) input - to what pin?
Post by: mattias on May 17, 2010, 03:00:34 AM
The "reference sensor" is for the single tooth on the flywheel, which masks the audi trigger. It is NOT the primary trigger.
Title: Re: RPM (engine speed) input - to what pin?
Post by: ranz on May 17, 2010, 03:07:34 AM
Quote from: mattias on May 17, 2010, 03:00:34 AM
The "reference sensor" is for the single tooth on the flywheel, which masks the audi trigger. It is NOT the primary trigger.
WTF ??? did I really got all it wrong???
But the manual says:

Swapping the “Crank Home” pins:

         Inside the engine bay underneath the black plastic power output stage cover you'll find a row of electrical plugs.  Locate the 3 pin black female connector that leads to a black 3 pin male connector that goes to one of the VR sensors attached to the bell housing on the transmission.  This is the sensor that reads the pin on the flywheel, and two of the pins on the car harness need to be swapped.  To do this... etc.

So, from it I understand that primary trigger is the single tooth on flywheel.

Also, RPM sensor reads endless tooth on the flywheel, there is no missing tooth or anything else what is usable for somekinde of trigger???
Title: Re: RPM (engine speed) input - to what pin?
Post by: peter_jensen on May 17, 2010, 04:15:07 AM
Some hints

http://www.vems.hu/wiki/index.php?page=MembersPage%2FPeterJensen/AudiSwiring


G28 pin 47 Engine speed sensor
G4 pin 49 Ref tooth
G40 Hall sensor 
Title: Re: RPM (engine speed) input - to what pin?
Post by: ranz on May 17, 2010, 04:27:18 AM
Quote from: peter_jensen on May 17, 2010, 04:15:07 AM
Some hints

http://www.vems.hu/wiki/index.php?page=MembersPage%2FPeterJensen/AudiSwiring


G28 pin 47 Engine speed sensor
G4 pin 49 Ref tooth
G40 Hall sensor 
I have these schematics, but the concerne is: This schematic is NOT done yet and there can become errors.
And I have already made some modifications to that.
Also, can someone explane me how can be the primary trigger RPM sensor what reads endless tooth on flywheel???
Title: Re: RPM (engine speed) input - to what pin?
Post by: peter_jensen on May 17, 2010, 05:09:48 AM
The schematic i made is working but it is not like the Vems web shop PnP.

The primary trigger senses the 135 teeth on the flywheel. The hall and sec trigger must come at the same time and when that happens the ecu knows that cyl1 is in compression I,e 62 BTDC and then we start counting the tooth on the flywheel.

The Audi trigger is complicated to understand for a newbie but don't pay attention how it works, just do like people tell you to do.

Peter   
Title: Re: RPM (engine speed) input - to what pin?
Post by: ranz on May 17, 2010, 05:19:15 AM
Thaks for helping :)
So, do I get it right.
Primary trigger: Engine speed sensor VR
Secondary trigger: Hall sender
And analog CH7/VR: Reference sensor

When I order my ecu, do I need specify some extra stuff? or it is same as PnP Audi AAN, but wiht standard conector?
Title: Re: RPM (engine speed) input - to what pin?
Post by: mattias on May 17, 2010, 08:08:15 AM
Just order a standard ECU with primary VR and secondary "auditrigger", read the notes in the webshop:
http://shop.vems.hu/catalog/assembled-controller-p-48.html

If you want more personal support, turn to a local reseller and arrange to buy everything from them.

The secondary trigger is the VR/inductive reference sensor, that is why ECUs made for this trigger have two VR circuits (LM1815) to filter the signal. The cam sync (Hall) is masked by the reference tooth and is wired to a third input.

Relevant link:
http://www.vems.hu/wiki/index.php?page=VemsAudiAan