Accel Enrichment w/ Variable TPS

[Golfer_705]

With the TPS disconnected I'm now getting a 380ADC count. Jumping TPS to VREF makes no change to the ADC. What do you recommend checking around the TPS pin on the main board? I do not have any wires shorting/rubbing and the board doesn't appear burnt did I miss anything?

[MercyFlush]

With the TPS disconnected I'm now getting a 380ADC count. Jumping TPS to VREF makes no change to the ADC. What do you recommend checking around the TPS pin on the main board? I do not have any wires shorting/rubbing and the board doesn't appear burnt did I miss anything?

I'd suggest having a look here

http://www.diyautotune.com/diypnp/docs1_5/main_assembly.html

and download the BOM and use that to show you what the following resistors are.

Use an online resistor coloured chart to speed up the process as needed.

Input 1: R14, R15, R29, R30, Q8, U3
Input 2: R16, R17, R18, R19, Q9, U3

Check those as you might have put a resistor in wrong and it's buffering the input too much or wrong etc.

The following has a pinout for the microsquirt board (white one) which plugs into the main board. You could even put a wire directly to the pin 13 of J2 and try that.

http://members.cisdi.com/~anesthes/projects/prom/megasquirt/docs/module.html

[Golfer_705]

I'd suggest having a look here

http://www.diyautotune.com/diypnp/docs1_5/main_assembly.html

and download the BOM and use that to show you what the following resistors are.

Use an online resistor coloured chart to speed up the process as needed.

Input 1: R14, R15, R29, R30, Q8, U3
Input 2: R16, R17, R18, R19, Q9, U3

Check those as you might have put a resistor in wrong and it's buffering the input too much or wrong etc.

The following has a pinout for the microsquirt board (white one) which plugs into the main board. You could even put a wire directly to the pin 13 of J2 and try that.
http://members.cisdi.com/~anesthes/p...cs/module.html

Thanks for the feedback.

I tested input 1 and 2 circuit, the resistance was good, all seems well

I opened the case to test TPS Sig and J2 pin 13 live voltage.

TPS Sig-SG showed .82V (same voltage as testing harness closed throttle) but steadly fell to 160mV. Same result testing testing from J2 pin 13.

ADC still starts low and floats to ~380ADC

Seems like something wrong with the main board or the ms module

Thanks for all your help

[MercyFlush]

Thanks for the feedback.

I tested input 1 and 2 circuit, the resistance was good, all seems well

I opened the case to test TPS Sig and J2 pin 13 live voltage.

TPS Sig-SG showed .82V (same voltage as testing harness closed throttle) but steadly fell to 160mV. Same result testing testing from J2 pin 13.

ADC still starts low and floats to ~380ADC

Seems like something wrong with the main board or the ms module

Thanks for all your help

Hmm very odd! I'm glad to help

I'd suggest taking a multimeter and checking for continuity between TPS Sig and Pin 13 of J2. It sounds like the solder pad for TPS sig might have been damaged at some point, or even the pcbs traces were damaged. You might be able to run your tps directly to pin13 of J2 and bypass all the other stuff, but that's probably a last resort.

If you hook the diypnp up as usual (with the white board installed), and power it up and run a multimeter from ground to pin 13 J2 reading in voltage you should get a varying voltage with the movement of the pedal. If not then the circuit from the tps sig to the J2 connector is not right. It might pay to remove the white board and probe pin 13 as before and see if the value changes, as that might indicate an issue with the white board.

I guess you could try and see if you can trace the tps sig track back to another spot where you can hook into (if the actual tps sig solder pad is broken). Sometimes if the heat is too hot you can accidentally take the copper pad off the board and break the connection.

I'm kinda just throwing these ideas out there but how the voltage seems to rise to a value that sounds exactly like what my tps did BEFORE I hooked it up. So this is why I believe that the signal is not actually getting to the main board.

[Golfer_705]

Hmm very odd! I'm glad to help

I'd suggest taking a multimeter and checking for continuity between TPS Sig and Pin 13 of J2. It sounds like the solder pad for TPS sig might have been damaged at some point, or even the pcbs traces were damaged. You might be able to run your tps directly to pin13 of J2 and bypass all the other stuff, but that's probably a last resort.

If you hook the diypnp up as usual (with the white board installed), and power it up and run a multimeter from ground to pin 13 J2 reading in voltage you should get a varying voltage with the movement of the pedal. If not then the circuit from the tps sig to the J2 connector is not right. It might pay to remove the white board and probe pin 13 as before and see if the value changes, as that might indicate an issue with the white board.

I guess you could try and see if you can trace the tps sig track back to another spot where you can hook into (if the actual tps sig solder pad is broken). Sometimes if the heat is too hot you can accidentally take the copper pad off the board and break the connection.

I'm kinda just throwing these ideas out there but how the voltage seems to rise to a value that sounds exactly like what my tps did BEFORE I hooked it up. So this is why I believe that the signal is not actually getting to the main board.

Retested this morning. TPS voltage was stable at pin 52 off the adapter board but started to fall testing from either of the pin 52 outputs on the adapter board.

Trimmed Pin 52 header from the adapter board and soldered direct to the TPS sig on the main board. Voltage is stable now and the TPS calibrates normally. something screwy going on within the adapter board shorting to ground. Seems to be fixed now. Time for a test drive! :D:D:D

Thanks again MercyFlush

[MercyFlush]

Retested this morning. TPS voltage was stable at pin 52 off the adapter board but started to fall testing from either of the pin 52 outputs on the adapter board.

Trimmed Pin 52 header from the adapter board and soldered direct to the TPS sig on the main board. Voltage is stable now and the TPS calibrates normally. something screwy going on within the adapter board shorting to ground. Seems to be fixed now. Time for a test drive! :D:D:D

Thanks again MercyFlush

Whooo!!

Glad you got it sorted ;)
Enjoy Acceleration Enrichment, it really makes a big improvement not to mention how much better your idle can be with closed loop!

[McGyver]

It's not that I don't trust the internet, but I like to have a reference for all of the wiring as I build/install MegaSquirt.

I am using the following manuals from wedophones.com
http://wedophones.com/Manuals/BMW/19...g%20Manual.pdf
http://wedophones.com/Manuals/BMW/19...g%20Manual.pdf

Looking at the 1989 325i Manual on Sheet 1360-7:

Pin 1: Closed Throttle (Idle)
Pin 2: GND
Pin 3: Wide Open Throttle



Looking at the 1994 Manual:

m42 DME 1.7 on Sheet 1210.9-05:

Pin 1: 5V
Pin 2: Signal
Pin 3: GND



m50 MS40 on Sheet 1210.10-05:

Pin 1: GND
Pin 2: Signal
Pin 3: 5V



m50 DME3.3.1 on Sheet 1210.13-05:

Pin 1: GND
Pin 2: Signal (incorrectly also lists this as 5V)
Pin 3: 5V



s50 DME 3.3 on Sheet 1210.14-05:

Pin 1: Signal
Pin 2: 5V
Pin 3: GND



Per Realoem.com, the m42, m50, and s50 all use the same sensor (13631721456). As long as the signal is being read on Pin 2, the only difference between swapping Pins 1&3 (5V and GND) would having the TPS read Idle to WOT as 0 -> 5V or 5 -> 0V.

I don't understand why the s50 has the signal on Pin 1. Did the ETM incorrectly label the pins for the s50?!?!