Updated Throttle Position Switch (TPS) Simulation

I recently started to suspect that I had made a mistake with this simulation, getting the timing of the outputs relative to the throttle position incorrect. I’ve now completed re-measuring this and yes, it is wrong, so here is the method, results and correction.

First step was to remove the TPS from my car and then 3D print a way of holding a scale and a pointer so I can move the TPS through it’s range and make measurements.

I hooked up a multimeter and recorded some positions. The scale I made does not line up with the TPS so that zero on the scale is zero degrees (angle) of the TPS so an adjustment needs to be made.

The full range of the TPS measured from 11 degrees to 114 degrees, giving a range of 103 degrees. It would have been nice if Bosch had designed it to give 100 degrees of range, ah well…

This corresponds to 0% – 100% throttle giving 103 / 100 = 1.03 degrees per %.

The idle output is grounded from 0 degrees to 1.5 degrees, which corresponds to 0% to 1.45%.

The WOT output is grounded from 83 degrees to 103 degrees, which corresponds to 80.58% to 100%. This was a surprise. Previously I used 90% which I believe I read from somewhere but I cannot remember where. I will come back to this value in a bit.

Now for the enrichment pulses. These pulses alternate on pins nine and 20 as the TPS is moved through it’s range.

Pin nine is first grounded at nine degrees and is last grounded at 64 degrees, which corresponds to 6.8% to 62.14%. It remained grounded from 62.14% to 100%.
That is a range of 57 degrees.

Pin 20 is first grounded at three degrees and is last grounded at 62 degrees, which corresponds to 2.91% to 60.19%. It remained high (not grounded) from 60.19% to 100%.
That is a range of 59 degrees.

I didn’t measure when each enrichment pulse started and stopped because I don’t think my 3D printed scale doo-dad is accurate enough, instead I decided to calculate it.

Here is a image taken from SW-EM Bosch D-Jet Notes in which I have made measurements.

There is a slight angle to the image so the measurements won’t be highly precise. The red line is the base line – it indicates where the idle pin stops being grounded.

Working backwards from the red line 1.5% is the limit of travel of the mechanism. All other measurements are made from this line.

Measuring the enrichment fingers I got 54.93 degrees which is close to my measured value for pin nine’s range of 57 degrees, two degrees off. Looking at this range we can see it is divided into 37 segments, alternating PCB trace and no trace.

57 / 37 = 1.54 degrees for each finger and gap width, which corresponds to 1.49%.

From this we can now calculate the throttle % for the start and end of each enrichment pulse.

he 83 degrees point that WOT is grounded is strange. I’ve drawn it on the image but it doesn’t correspond to the traces. My guess is that the PCB in our TPSs is different and has the WOT point earlier than this PCB seems to indicate. I’ve already taken my TPS apart once to clean it and I am afraid of breaking the plastic tabs so I won’t be taking it apart again just to see. If anyone has a picture please post it so we can compare.

Here are the results of the calculations.

Here is the new simulation model. Copy and paste into a file called TPS.lib.

* D-Jetronic Throttle Position Switch
* Version 2.0, September 2022
* (C) andy@britishideas.com 2022

.subckt tps position enrich_en idle full_throttle enrich_a enrich_b vcc gnd

.model DIODE D 
.model BCY58 npn 
.model BSX95 npn 
.model AUY21 pnp 

XS2 0 Net-_R11-Pad2_ POSITION 0 vcs close_v=0.083
R2 VCC Net-_R11-Pad2_ 1k
Q2 Net-_Q1-Pad3_ Net-_Q2-Pad2_ 0 BCY58
R11 Net-_Q2-Pad2_ Net-_R11-Pad2_ 10k
R10 Net-_Q1-Pad2_ Net-_R1-Pad1_ 10k
Q1 PA_1 Net-_Q1-Pad2_ Net-_Q1-Pad3_ BCY58
R1 Net-_R1-Pad1_ 0 1k
XS1 VCC Net-_R1-Pad1_ POSITION 0 vcs close_v=0.068
R9 VCC Net-_R18-Pad2_ 1k
XS9 0 Net-_R18-Pad2_ POSITION 0 vcs close_v=0.0145
Q9 IDLE Net-_Q9-Pad2_ 0 BCY58
R18 Net-_Q9-Pad2_ Net-_R18-Pad2_ 10k
* R23 VCC IDLE 1k
R40 Net-_R40-Pad1_ 0 1k
XS18 VCC Net-_R40-Pad1_ POSITION 0 vcs close_v=0.8058
Q18 FULL_THROTTLE Net-_Q18-Pad2_ 0 BCY58
R45 Net-_Q18-Pad2_ Net-_R40-Pad1_ 10k
* R46 VCC FULL_THROTTLE 1k
R19 VCC PA_1 1k
XS11 0 Net-_R25-Pad2_ POSITION 0 vcs close_v=0.1428
R25 VCC Net-_R25-Pad2_ 1k
Q11 Net-_Q10-Pad3_ Net-_Q11-Pad2_ 0 BCY58
R33 Net-_Q11-Pad2_ Net-_R25-Pad2_ 10k
R32 Net-_Q10-Pad2_ Net-_R24-Pad1_ 10k
Q10 PA_2 Net-_Q10-Pad2_ Net-_Q10-Pad3_ BCY58
R24 Net-_R24-Pad1_ 0 1k
XS10 VCC Net-_R24-Pad1_ POSITION 0 vcs close_v=0.1278
R41 VCC PA_2 1k
XS20 0 Net-_R48-Pad2_ POSITION 0 vcs close_v=0.2026
R48 VCC Net-_R48-Pad2_ 1k
Q20 Net-_Q19-Pad3_ Net-_Q20-Pad2_ 0 BCY58
R56 Net-_Q20-Pad2_ Net-_R48-Pad2_ 10k
R55 Net-_Q19-Pad2_ Net-_R47-Pad1_ 10k
Q19 PA_3 Net-_Q19-Pad2_ Net-_Q19-Pad3_ BCY58
R47 Net-_R47-Pad1_ 0 1k
XS19 VCC Net-_R47-Pad1_ POSITION 0 vcs close_v=0.1877
R63 VCC PA_3 1k
XS28 0 Net-_R68-Pad2_ POSITION 0 vcs close_v=0.2624
R68 VCC Net-_R68-Pad2_ 1k
Q28 Net-_Q27-Pad3_ Net-_Q28-Pad2_ 0 BCY58
R76 Net-_Q28-Pad2_ Net-_R68-Pad2_ 10k
R75 Net-_Q27-Pad2_ Net-_R67-Pad1_ 10k
Q27 PA_4 Net-_Q27-Pad2_ Net-_Q27-Pad3_ BCY58
R67 Net-_R67-Pad1_ 0 1k
XS27 VCC Net-_R67-Pad1_ POSITION 0 vcs close_v=0.2475
R83 VCC PA_4 1k
XS36 0 Net-_R88-Pad2_ POSITION 0 vcs close_v=0.3223
R88 VCC Net-_R88-Pad2_ 1k
Q36 Net-_Q35-Pad3_ Net-_Q36-Pad2_ 0 BCY58
R96 Net-_Q36-Pad2_ Net-_R88-Pad2_ 10k
R95 Net-_Q35-Pad2_ Net-_R87-Pad1_ 10k
Q35 PA_5 Net-_Q35-Pad2_ Net-_Q35-Pad3_ BCY58
R87 Net-_R87-Pad1_ 0 1k
XS35 VCC Net-_R87-Pad1_ POSITION 0 vcs close_v=0.3073
R103 VCC PA_5 1k
XS4 0 Net-_R13-Pad2_ POSITION 0 vcs close_v=0.3821
R4 VCC Net-_R13-Pad2_ 1k
Q4 Net-_Q3-Pad3_ Net-_Q4-Pad2_ 0 BCY58
R13 Net-_Q4-Pad2_ Net-_R13-Pad2_ 10k
R12 Net-_Q3-Pad2_ Net-_R12-Pad2_ 10k
Q3 PA_6 Net-_Q3-Pad2_ Net-_Q3-Pad3_ BCY58
R3 Net-_R12-Pad2_ 0 1k
XS3 VCC Net-_R12-Pad2_ POSITION 0 vcs close_v=0.3671
R20 VCC PA_6 1k
XS13 0 Net-_R27-Pad2_ POSITION 0 vcs close_v=0.4419
R27 VCC Net-_R27-Pad2_ 1k
Q13 Net-_Q12-Pad3_ Net-_Q13-Pad2_ 0 BCY58
R35 Net-_Q13-Pad2_ Net-_R27-Pad2_ 10k
R34 Net-_Q12-Pad2_ Net-_R26-Pad1_ 10k
Q12 PA_7 Net-_Q12-Pad2_ Net-_Q12-Pad3_ BCY58
R26 Net-_R26-Pad1_ 0 1k
XS12 VCC Net-_R26-Pad1_ POSITION 0 vcs close_v=0.4270
R42 VCC PA_7 1k
XS22 0 Net-_R50-Pad2_ POSITION 0 vcs close_v=0.5017
R50 VCC Net-_R50-Pad2_ 1k
Q22 Net-_Q21-Pad3_ Net-_Q22-Pad2_ 0 BCY58
R58 Net-_Q22-Pad2_ Net-_R50-Pad2_ 10k
R57 Net-_Q21-Pad2_ Net-_R49-Pad1_ 10k
Q21 PA_8 Net-_Q21-Pad2_ Net-_Q21-Pad3_ BCY58
R49 Net-_R49-Pad1_ 0 1k
XS21 VCC Net-_R49-Pad1_ POSITION 0 vcs close_v=0.4868
R64 VCC PA_8 1k
XS30 0 Net-_R70-Pad2_ POSITION 0 vcs close_v=0.5616
R70 VCC Net-_R70-Pad2_ 1k
Q30 Net-_Q29-Pad3_ Net-_Q30-Pad2_ 0 BCY58
R78 Net-_Q30-Pad2_ Net-_R70-Pad2_ 10k
R77 Net-_Q29-Pad2_ Net-_R69-Pad1_ 10k
Q29 PA_9 Net-_Q29-Pad2_ Net-_Q29-Pad3_ BCY58
R69 Net-_R69-Pad1_ 0 1k
XS29 VCC Net-_R69-Pad1_ POSITION 0 vcs close_v=0.5466
R84 VCC PA_9 1k
XS38 0 Net-_R90-Pad2_ POSITION 0 vcs close_v=1.00
R90 VCC Net-_R90-Pad2_ 1k
Q38 Net-_Q37-Pad3_ Net-_Q38-Pad2_ 0 BCY58
R98 Net-_Q38-Pad2_ Net-_R90-Pad2_ 10k
R97 Net-_Q37-Pad2_ Net-_R89-Pad1_ 10k
Q37 PA_10 Net-_Q37-Pad2_ Net-_Q37-Pad3_ BCY58
R89 Net-_R89-Pad1_ 0 1k
XS37 VCC Net-_R89-Pad1_ POSITION 0 vcs close_v=0.6064
R104 VCC PA_10 1k
Q54 Net-_Q54-Pad1_ PA_1 Net-_Q54-Pad3_ BCY58
Q55 Net-_Q54-Pad3_ PA_2 Net-_Q55-Pad3_ BCY58
Q56 Net-_Q55-Pad3_ PA_3 Net-_Q56-Pad3_ BCY58
Q57 Net-_Q56-Pad3_ PA_4 Net-_Q57-Pad3_ BCY58
Q58 Net-_Q57-Pad3_ PA_5 Net-_Q58-Pad3_ BCY58
Q59 Net-_Q58-Pad3_ PA_6 Net-_Q59-Pad3_ BCY58
Q60 Net-_Q59-Pad3_ PA_7 Net-_Q60-Pad3_ BCY58
Q61 Net-_Q60-Pad3_ PA_8 Net-_Q61-Pad3_ BCY58
Q62 Net-_Q61-Pad3_ PA_9 Net-_Q62-Pad3_ BCY58
Q63 Net-_Q62-Pad3_ PA_10 0 BCY58
XS6 0 Net-_R15-Pad2_ POSITION 0 vcs close_v=0.0441
R6 VCC Net-_R15-Pad2_ 1k
Q6 Net-_Q5-Pad3_ Net-_Q6-Pad2_ 0 BCY58
R15 Net-_Q6-Pad2_ Net-_R15-Pad2_ 10k
R14 Net-_Q5-Pad2_ Net-_R14-Pad2_ 10k
Q5 PB_1 Net-_Q5-Pad2_ Net-_Q5-Pad3_ BCY58
R5 Net-_R14-Pad2_ 0 1k
XS5 VCC Net-_R14-Pad2_ POSITION 0 vcs close_v=0.0291
R21 VCC PB_1 1k
XS15 0 Net-_R29-Pad2_ POSITION 0 vcs close_v=0.1039
R29 VCC Net-_R29-Pad2_ 1k
Q15 Net-_Q14-Pad3_ Net-_Q15-Pad2_ 0 BCY58
R37 Net-_Q15-Pad2_ Net-_R29-Pad2_ 10k
R36 Net-_Q14-Pad2_ Net-_R28-Pad1_ 10k
Q14 PB_2 Net-_Q14-Pad2_ Net-_Q14-Pad3_ BCY58
R28 Net-_R28-Pad1_ 0 1k
XS14 VCC Net-_R28-Pad1_ POSITION 0 vcs close_v=0.0889
R43 VCC PB_2 1k
XS24 0 Net-_R52-Pad2_ POSITION 0 vcs close_v=0.1637
R52 VCC Net-_R52-Pad2_ 1k
Q24 Net-_Q23-Pad3_ Net-_Q24-Pad2_ 0 BCY58
R60 Net-_Q24-Pad2_ Net-_R52-Pad2_ 10k
R59 Net-_Q23-Pad2_ Net-_R51-Pad1_ 10k
Q23 PB_3 Net-_Q23-Pad2_ Net-_Q23-Pad3_ BCY58
R51 Net-_R51-Pad1_ 0 1k
XS23 VCC Net-_R51-Pad1_ POSITION 0 vcs close_v=0.1488
R65 VCC PB_3 1k
XS32 0 Net-_R72-Pad2_ POSITION 0 vcs close_v=0.2235
R72 VCC Net-_R72-Pad2_ 1k
Q32 Net-_Q31-Pad3_ Net-_Q32-Pad2_ 0 BCY58
R80 Net-_Q32-Pad2_ Net-_R72-Pad2_ 10k
R79 Net-_Q31-Pad2_ Net-_R71-Pad1_ 10k
Q31 PB_4 Net-_Q31-Pad2_ Net-_Q31-Pad3_ BCY58
R71 Net-_R71-Pad1_ 0 1k
XS31 VCC Net-_R71-Pad1_ POSITION 0 vcs close_v=0.2086
R85 VCC PB_4 1k
XS40 0 Net-_R100-Pad2_ POSITION 0 vcs close_v=0.2834
R92 VCC Net-_R100-Pad2_ 1k
Q40 Net-_Q39-Pad3_ Net-_Q40-Pad2_ 0 BCY58
R100 Net-_Q40-Pad2_ Net-_R100-Pad2_ 10k
R99 Net-_Q39-Pad2_ Net-_R91-Pad1_ 10k
Q39 PB_5 Net-_Q39-Pad2_ Net-_Q39-Pad3_ BCY58
R91 Net-_R91-Pad1_ 0 1k
XS39 VCC Net-_R91-Pad1_ POSITION 0 vcs close_v=0.2684
R105 VCC PB_5 1k
XS8 0 Net-_R17-Pad2_ POSITION 0 vcs close_v=0.3432
R8 VCC Net-_R17-Pad2_ 1k
Q8 Net-_Q7-Pad3_ Net-_Q8-Pad2_ 0 BCY58
R17 Net-_Q8-Pad2_ Net-_R17-Pad2_ 10k
R16 Net-_Q7-Pad2_ Net-_R16-Pad2_ 10k
Q7 PB_6 Net-_Q7-Pad2_ Net-_Q7-Pad3_ BCY58
R7 Net-_R16-Pad2_ 0 1k
XS7 VCC Net-_R16-Pad2_ POSITION 0 vcs close_v=0.3282
R22 VCC PB_6 1k
R31 VCC Net-_R31-Pad2_ 1k
Q17 Net-_Q16-Pad3_ Net-_Q17-Pad2_ 0 BCY58
R39 Net-_Q17-Pad2_ Net-_R31-Pad2_ 10k
R38 Net-_Q16-Pad2_ Net-_R30-Pad1_ 10k
Q16 PB_7 Net-_Q16-Pad2_ Net-_Q16-Pad3_ BCY58
R30 Net-_R30-Pad1_ 0 1k
XS16 VCC Net-_R30-Pad1_ POSITION 0 vcs close_v=0.3881
R44 VCC PB_7 1k
R54 VCC Net-_R54-Pad2_ 1k
Q26 Net-_Q25-Pad3_ Net-_Q26-Pad2_ 0 BCY58
R62 Net-_Q26-Pad2_ Net-_R54-Pad2_ 10k
R61 Net-_Q25-Pad2_ Net-_R53-Pad1_ 10k
Q25 PB_8 Net-_Q25-Pad2_ Net-_Q25-Pad3_ BCY58
R53 Net-_R53-Pad1_ 0 1k
R66 VCC PB_8 1k
XS34 0 Net-_R74-Pad2_ POSITION 0 vcs close_v=0.5227
R74 VCC Net-_R74-Pad2_ 1k
Q34 Net-_Q33-Pad3_ Net-_Q34-Pad2_ 0 BCY58
R82 Net-_Q34-Pad2_ Net-_R74-Pad2_ 10k
R81 Net-_Q33-Pad2_ Net-_R73-Pad1_ 10k
Q33 PB_9 Net-_Q33-Pad2_ Net-_Q33-Pad3_ BCY58
R73 Net-_R73-Pad1_ 0 1k
XS33 VCC Net-_R73-Pad1_ POSITION 0 vcs close_v=0.5077
R86 VCC PB_9 1k
XS42 0 Net-_R102-Pad2_ POSITION 0 vcs close_v=0.5825
R94 VCC Net-_R102-Pad2_ 1k
Q42 Net-_Q41-Pad3_ Net-_Q42-Pad2_ 0 BCY58
R102 Net-_Q42-Pad2_ Net-_R102-Pad2_ 10k
R101 Net-_Q41-Pad2_ Net-_R101-Pad2_ 10k
Q41 PB_10 Net-_Q41-Pad2_ Net-_Q41-Pad3_ BCY58
R93 Net-_R101-Pad2_ 0 1k
XS41 VCC Net-_R101-Pad2_ POSITION 0 vcs close_v=0.5675
R106 VCC PB_10 1k
XS26 0 Net-_R54-Pad2_ POSITION 0 vcs close_v=0.4628
XS17 0 Net-_R31-Pad2_ POSITION 0 vcs close_v=0.4030
XS25 VCC Net-_R53-Pad1_ POSITION 0 vcs close_v=0.4479
R108 VCC Net-_Q44-Pad1_ 1k
Q53 Net-_Q52-Pad3_ PB_10 0 BCY58
Q52 Net-_Q51-Pad3_ PB_9 Net-_Q52-Pad3_ BCY58
Q51 Net-_Q50-Pad3_ PB_8 Net-_Q51-Pad3_ BCY58
Q50 Net-_Q49-Pad3_ PB_7 Net-_Q50-Pad3_ BCY58
Q49 Net-_Q48-Pad3_ PB_6 Net-_Q49-Pad3_ BCY58
Q48 Net-_Q47-Pad3_ PB_5 Net-_Q48-Pad3_ BCY58
Q47 Net-_Q46-Pad3_ PB_4 Net-_Q47-Pad3_ BCY58
Q46 Net-_Q45-Pad3_ PB_3 Net-_Q46-Pad3_ BCY58
Q45 Net-_Q44-Pad3_ PB_2 Net-_Q45-Pad3_ BCY58
Q44 Net-_Q44-Pad1_ PB_1 Net-_Q44-Pad3_ BCY58
Q67 VCC Net-_Q67-Pad2_ Net-_Q65-Pad3_ BCY58
Q65 VCC N_ENRICH_EN Net-_Q65-Pad3_ BCY58
Q43 N_ENRICH_EN ENRICH_EN 0 BCY58
R107 VCC N_ENRICH_EN 1k
R109 VCC Net-_Q54-Pad1_ 1k
R113 Net-_Q65-Pad3_ 0 1k
R117 VCC Net-_Q69-Pad1_ 1k
Q69 Net-_Q69-Pad1_ Net-_Q69-Pad2_ 0 BCY58
* R121 VCC ENRICH_A 1k
Q71 ENRICH_A Net-_Q71-Pad2_ 0 BCY58
R115 Net-_Q69-Pad2_ Net-_Q65-Pad3_ 1k
R119 Net-_Q71-Pad2_ Net-_Q69-Pad1_ 1k
R111 Net-_Q67-Pad2_ Net-_Q54-Pad1_ 1k
Q66 VCC Net-_Q66-Pad2_ Net-_Q64-Pad3_ BCY58
Q64 VCC N_ENRICH_EN Net-_Q64-Pad3_ BCY58
R112 Net-_Q64-Pad3_ 0 1k
R116 VCC Net-_Q68-Pad1_ 1k
Q68 Net-_Q68-Pad1_ Net-_Q68-Pad2_ 0 BCY58
* R120 VCC ENRICH_B 1k
Q70 ENRICH_B Net-_Q70-Pad2_ 0 BCY58
R114 Net-_Q68-Pad2_ Net-_Q64-Pad3_ 1k
R118 Net-_Q70-Pad2_ Net-_Q68-Pad1_ 1k
R110 Net-_Q66-Pad2_ Net-_Q44-Pad1_ 1k

.ends

.subckt vcs in_pin out_pin vcc_pin gnd_pin close_v=5.0
.model vcs_switch sw vt={close_v} vh=0.01 ron=1 roff=1Meg
S1 in_pin out_pin vcc_pin gnd_pin vcs_switch
.ends

and the corresponding chart showing it’s operation.

Download the PDF for the measurement rose (print at 100%, US letter size), the base STL and the pointer STL.

Base:

Pointer: