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Hacking up Honda's ECU
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 Post subject: Re: VSS sensor signal
PostPosted: Tue Oct 21, 2003 5:23 pm 
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Joined: Tue Jul 27, 2004 2:36 am
Posts: 86
Location: Hungary / Europe
Maybe you are right. But I will not create a simple divider, but a device like HKS:

"The HKS Speed Limit Defencer (SLD) device works by intercepting the VSS signal and substituting its own signal to the ECU. This device has four wires, two of them for power and ground and of the other two, one receives the VSS signal and the other feeds a substitute signal into the ECU.
When the SLD device detects that the VSS signal is indicating that the car is travelling at 180kph, it substitutes a signal to the ECU indicating a lower speed. Because the VSS signal is not a major parameter used by the engine ECU to control engine operation, this method effectively bypasses the artificial 180kph top speed limit in the best manner."

Source:
http://www.vtec.net/articles/view-artic ... le_id=7575

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 Post subject: Re: VSS sensor signal
PostPosted: Fri Oct 24, 2003 1:53 am 
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Joined: Tue Jul 27, 2004 2:14 am
Posts: 429
i have found that the mph and hz are close...it's been awhile but i remember that 30mph was close to 30hz or 300hz (can't recall the factor being 1 or 10).

i would LOVE to see a diagram for the division circuit you guys are refering to...please if you could help i'd appreciate it.

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Post Edited (10-24-03 01:54)


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 Post subject: Re: VSS sensor signal
PostPosted: Fri Oct 24, 2003 5:15 am 
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Joined: Tue Jul 27, 2004 2:36 am
Posts: 86
Location: Hungary / Europe
Delude: Where have you find this information? I have measured it.

My last general question:
Does the VTEC activation depend on VSS signal or not?

If it is depend on, I can't create speed limit defencer because the activation speed is about 180 kph in my car. :))

Has somebody got a good link about VTEC activation?

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 Post subject: Re: VSS sensor signal
PostPosted: Fri Oct 24, 2003 12:20 pm 
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Posts: 429
Vtec engagement is VERY dependant on a minimum vss signal...you just need to clamp/limit the output of your device to just under the value that causes the speed limiter.

again: can anyone share the simple frequency divider circuit that is mentioned in this thread? even a link or data sheet...i'm not PIC-savey nor STAMP-proficient, but i'd pay for a working prog if that is how you are doing it.

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 Post subject: Re: VSS sensor signal
PostPosted: Fri Oct 24, 2003 1:18 pm 
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Posts: 86
Location: Hungary / Europe
Delude: I have only a device with microcontroller and a small program.

Image

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 Post subject: Re: VSS sensor signal
PostPosted: Fri Oct 24, 2003 2:04 pm 
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Joined: Tue Jul 27, 2004 2:09 am
Posts: 4380
Location: Cincinnati, Ohio
hondainfo: the VSS - vtec interaction we are talking about is very simple. The ECU checks to make sure the car is going a minimum of 25mph (40kph) in the US before activating Vtec.

as long as your device does not alter the frequency until the frequency is greater than ~120HZ, your car should run perfectly.

In |out (HZ)
1 | 1
.. | ..
119|119
120|120
121|120
122|120
123|120
...|...|

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 Post subject: Re: VSS sensor signal
PostPosted: Sat Oct 25, 2003 9:18 pm 
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Joined: Tue Jul 27, 2004 2:36 am
Posts: 86
Location: Hungary / Europe
HELP ME!

I've created the new code and I have tried it. I think it works fine BUT:

My car doesn't want to switch to VTEC at 4th gear. I speed 200 kph at 6000 RPM in 4th gear without VTEC.
Acceleration to 200 kph above 170 kph is very slow because missing VTEC.

WHY?

(Conditions: 1997 Honda Prelude 2.2VTI, P5M ECU, 4 gear automatic transmission, VTEC switch point: 5250 RPM, It works fine at 1st, 2nd and 3th gear )

A question has occured to me: at all, have P5M got artifical speed limit, or not (my car works badly)?

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 Post subject: Re: VSS sensor signal
PostPosted: Mon Oct 27, 2003 6:44 pm 
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Location: Hungary / Europe
Here is a picture of the prototype:

http://193.91.73.232/honda/vssdev.jpg

Code:
;------------------------------------------------------------------------------
; Hondainfo's Speed Limit Defencer
; AT89C4051 mikrokontroller assembly program
; V1.2 2003.10.22
;------------------------------------------------------------------------------

$mod51

;------------------------------------------------------------------------------
; Theory:
;
; The VSS signal (measured data)
; At 60 km/h   Freq: 42 Hz
; At 100 km/h   Freq: 70 Hz
; At 120 km/h   Freq: 84 Hz
; At 170 km/h   Freq: 119 Hz
; duty in all case:50%
;
; This program is a simple signal copy when the frequency of signal is below 119 Hz
; Above 119Hz, the program switches to Virtual mode and sends Virtual
; 119 Hz signals to ECU independ on Input signal frequency.
;
;------------------------------------------------------------------------------
;------------------------------------------------------------------------------
; Memory variables:
;------------------------------------------------------------------------------
; pin definition

VSS_IN    EQU P3.7    ; Recieve VSS signal here
VSS_OUT   EQU P1.7   ; artifical VSS signal to ECU (0: transistor is closed, 1: transistor is opened, pull the signal to Ground)

VIRTUAL   bit 001h   ; mode: =1 Virtual, =0 real signal output
VSS_OLD   bit 002h   ; altering of sampled signal

COUNTR   data 030h   ; Real Counter counts the time beetween two VSS signal
COUNTV   data 031h   ; Virtual counter for artifical VSS signal output

;------------------------------------------------------------------------------
; Címdeffinition, interrupt table
;------------------------------------------------------------------------------
  RESET code 00000h
  org 0000h               ;starting here after Reset
   ljmp kezdet
  org 0003h               
   reti
  org 000bh               ;Timer 0 interrupt
   ljmp T0_int
  org 0013h               
   reti
  org 001bh               
   reti
  org 0023h               
   reti
  org 002bh   
   reti
  org 30h      

;------------------------------------------------------------------------------
;   22.1184 Mhz quartz
;   Timer 0 interrupt aprox: 0,0434 ms time base for measuring milisecs
;   - run 23040 times per a second
;    time period: 43 us
;    runing time max: 30 us
;------------------------------------------------------------------------------
T0_int:      PUSH PSW
      mov TL0,#0B0h      ; software reload
      mov TH0,#0FFh
      mov TCON,#050h
;*****MEASURING VSS SIGNAL
      jb VSS_IN,Ti0      ; jump if no signal (1->0 edge)
      jnb VSS_OLD,Ti0      ; jump if previous sample similar
      mov a,#192d      ; there is signal, check the counter
      clr c         ; 192x0,0434ms=8,33msec (119 Hz)
      subb A,COUNTR
      cpl c         ; If <= 8,33 msec then switch to virtual signal mode
      mov VIRTUAL,c      ; If > 8.33 msec then switch to Real signal mode
      mov COUNTR,#0ffh   ; Initial Real Counter
Ti0:      mov c,VSS_IN      ; sample altering
      mov VSS_OLD,c
      mov a,COUNTR
      xrl a,#250d      ; increment Real Counter, but max: 250
      jz Ti1         
      inc COUNTR      
;*****VIRTUAL COUNTER
Ti1:      mov a,COUNTV
      xrl a,#192d      ; increment Virtual Counter 0-192 cycle
      jnz Ti11
      mov COUNTV,#0ffh
Ti11:      inc COUNTV      
;*****REAL MODE SIGNAL COPY
Ti2:      jb VIRTUAL,Ti3      ; jump if Virtual mode
      mov c,VSS_IN      ; In Real Mode simple SIGNAL COPY
      cpl c
      mov VSS_OUT,c
      sjmp Ti4
;*****VIRTUAL MODE ARTIFICAL SIGNAL OUTPUT
Ti3:      mov a,#096d      ; Virtual signaling above 170 kph
      clr c         ; send 0 to output (pull to the ground)
      subb A,COUNTV      ; when Virtual Counter <=96
      cpl c         ; send 1 to output (release)
      mov VSS_OUT,c      ; when Virtual Counter >96
Ti4:      POP PSW
      reti         ; END OF INTERRUPT

;------------------------------------------------------------------------------
;Starting after Reset, int init
;------------------------------------------------------------------------------
kezdet:    clr VSS_OUT      ; init output
      mov c,VSS_IN      ; first altering
      mov VSS_OLD,c
      mov COUNTR,#250d
      mov COUNTV,#000d      
      clr VIRTUAL
      mov TMOD,#021h      ; init timers T1 mode 2 (Auto Reload, Serial Port)
      mov TL1,#0FFH       ; T0 mode 1 (16 bit timer, software reload, Interrupt)
      mov TH1,#0FFH       ; serial port timing 9600 baud (use for testing)
      mov TL0,#0B0h      ; 65536d-80d-t to the counter init
      mov TH0,#0FFh      ;
      mov SCON,#052H       ; serial port mode 1
      mov TCON,#050h      ; Timer1 , Timer0 indul
      mov IE,#092h      ; RI/TI int enabled, T0 int enabled
ciklus:      sjmp ciklus
end


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 Post subject: Re: VSS sensor signal
PostPosted: Mon Oct 27, 2003 6:48 pm 
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Joined: Tue Jul 27, 2004 2:36 am
Posts: 86
Location: Hungary / Europe
Oh shit, the phorum has fucked the TABULATORS :((

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 Post subject: Re: VSS sensor signal
PostPosted: Sat Nov 01, 2003 6:54 pm 
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Joined: Tue Jul 27, 2004 2:35 am
Posts: 111
i all know that the sensor outputs 4000 pulses for 1 mile travelled.


i'm in the works of build a digital speedometer..


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 Post subject: Re: VSS sensor signal
PostPosted: Mon Nov 03, 2003 3:22 pm 
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Joined: Tue Jul 27, 2004 2:36 am
Posts: 86
Location: Hungary / Europe
crxsirvtec:

Have You got a digital multimeter with freqency feature?
Measure the signal for us please. I very interest this freq data in similar speeds in CRX.

thnx

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 Post subject: Re: VSS sensor signal
PostPosted: Sat Nov 08, 2003 7:22 pm 
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Joined: Tue Jul 27, 2004 2:36 am
Posts: 86
Location: Hungary / Europe
Holly shit!

It developed today my car has no got 180kph speed limit!
All my VSS development was useless or not?

I think my speed limit defencer device works properly. I beleive my job was no pointless. I will try it on a real limited car.

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