DIY: SAP Sim

Originally Posted by serdar255

Can you send me a link to the board you used or something you recommend?
Thanks

http://e36-electronic.com/

Originally Posted by gpeterson

http://e36-electronic.com/

thanks, but i meant to reply to op, sorry.

Hey guys, E36 have a different output than e46, I sell simulators for both. I have tested on 3 different e46 with success.. work on e46 up to 03.. Email me for more info RomoGuy@aol.com selling the e46 Units for $90 shipped through paypal.

does this also work for the sulev m56?

Yes, It should with no problem, keep in mind, within 14 days, I will issue refund if you have any issues.

The PCB came from Radioshack too. I'm pretty sure that all the parts came from there.

Drewfus2101,

I created your design with some changes.
I used a DPDT relay I had in my junk box.
As an Electrical Engineer who used lots of 7805 voltage regulators in noisy environments it would be a good idea to use a 1uF filter cap at the input to the voltage regulator and a 0.1uF filter cap at the output. The 7805 are prone to oscillation when using long wires at the output. You can actually use a 78xx as an audio amplifier to drive a speaker! Just put your iPod to the regulated pin and a speaker to the output pin and you can get great fidelity audio. In the lab we used 7812 and got 8 watts RMS of audio power.

You do not need a potentiometer/trimmer just use a voltage divider using a 22ohm resistor and a 560ohm resistor and power both DME pins on the relay.
I get 0.196V which is close enough to 0.20V.

Now a question to all of you. I have an M56 SULEV engine so there is a secondary air - air mass meter. How do I deal with this????? Anyone figured this one?

Originally Posted by jbielefeld

Drewfus2101,

I created your design with some changes.
I used a DPDT relay I had in my junk box.
As an Electrical Engineer who used lots of 7805 voltage regulators in noisy environments it would be a good idea to use a 1uF filter cap at the input to the voltage regulator and a 0.1uF filter cap at the output. The 7805 are prone to oscillation when using long wires at the output. You can actually use a 78xx as an audio amplifier to drive a speaker! Just put your iPod to the regulated pin and a speaker to the output pin and you can get great fidelity audio. In the lab we used 7812 and got 8 watts RMS of audio power.

You do not need a potentiometer/trimmer just use a voltage divider using a 22ohm resistor and a 560ohm resistor and power both DME pins on the relay.
I get 0.196V which is close enough to 0.20V.

Now a question to all of you. I have an M56 SULEV engine so there is a secondary air - air mass meter. How do I deal with this????? Anyone figured this one?

Agreed... the sims I sell have filtering caps and use a fixed voltage divider instead of pots.

As for the M56 - I've looked into building sims for cars with a SAP MAF but don't have one to test on. Many newer cars use wideband O2s as well and those will be more work to build a sim for.

Drewfus2101,

I measured the Secondary Air - Mass Air Meter output using a shop vac to simulate the moving air. This a crude test. The secondary Mass Air meter w/o air flow had 60mV output. When the shop vac was pushing air through I got 3V output.
So, for now I made a voltage divider at the plug to keep the voltage at 2.5V.
The power pin supplied 5V so I used two 10k resistors tied together. One end going to the ground pin one end to 5V pin and the signal pin went to the junction of the voltage divider. Right now I still get the P1418 code with the sim alone. P1418 is Secondary Air Hose Clamped. I am assuming the air mass meter thinks there is no air flow so it thinks the air hose is blocked ( manifold valve closed).

The O2 sensors are the 5 wire type.
Combined Narrow Band and Pump Cells (5-wire).
Red wire = Ip
Yel wire = Vs/Ip
Blk wire = Vs
Wht wire = Heater-
Gry wire = Heater+
(All on the O2 sensor side of the plug.)

The formula for the O2 sensor is:
Vs = (RT/4F)*In(pO2atm/pO2test)
so the voltage range for the sensor is 0.9V for low oxygen and 0.1V for high oxygen. Wow, this is non-linear. The most linear part of the range is between 0.7V and 0.2V
Stoich is close to 0.45V (mid-range) so 0.2V is on the Oxygen rich side.

Sorry for the rambling but, just trying to get a grip on this as I write....

Drewfus2101,

Day one, no P1418 with the air mass meeter circuit.

jbielefeld, to clarify, you still need to sim the O2's AND the SAP MAF? Or have you tried just doing a SIM for the SAP MAF and see if that alone is good enough to prevent an error code?

For the M56 SULEV: I built/installed the sim and also fool the SAP MAF. So far still no P1418 code.
So, I needed to do both on the M56 1. Add the sim as per Drewfus2101 and 2. Add the voltage divider to the MAF connector.

O--10k--- - GND pin
|
O--10k--- - 5V pin
|
O-------- - Sig pin (2.5V)

Subscribed, this is an excellent writeup.