Bringing TBI and Multi Port Fuel Injection to a New Level.     EFI Conversions and Tuning! Seattle to Portland! E-mail Tuning Consultant!
Page 13 of 14 FirstFirst ... 3891011121314 LastLast
Results 181 to 195 of 207

Thread: 1997 F-Body ECM

  1. #181
    Fuel Injected!
    Join Date
    Jan 2012
    Location
    Poland
    Posts
    140
    Here are my findings for the unused pins:
    Attached Images Attached Images

  2. #182
    Fuel Injected!
    Join Date
    Jan 2019
    Location
    Canada
    Posts
    135
    Quote Originally Posted by dzidaV8 View Post
    Here are my findings for the unused pins:
    Thank you for this. I believe you may have given them to me earlier in my investigation. Problem I have is that one pin lacks Rs and Cs to make the connection to the pin. I wanted to see if someone knew what the function was or if it was used on some other car.

    I guess the function was still born. It will be interesting to see if TPU uses the input to modify spark or fuel.

    Thanks,
    Tom

  3. #183
    Fuel Injected!
    Join Date
    Jan 2019
    Location
    Canada
    Posts
    135
    Some troubles to report (all my fault). As my code got larger it crossed a location that the GM code TPU initialization uses. I had not taken enough care to see this happening and lost some hours debugging. Now I understand, the problem is simple but when it happened I figured watchdog timer, NMI, blowen stack and hundreds of other problems. My code now jumps over the location and all is back to normal.

    I need to re-run a bunch of testing to be sure result is not corrupt. <sigh>

    -Tom

  4. #184
    Fuel Injected!
    Join Date
    Jan 2019
    Location
    Canada
    Posts
    135
    Quote Originally Posted by kur4o View Post
    Now I have some other question related with interrupts.
    On 94-95 code eside can communicate over the aldl bus. It has E4 ID and the communication is handled by the SCISS. It works great when the engine is not running and I can log some memory regions real time for better understanding of the code. Somehow when the engine is started eside stops communicating. It just doesn`t handle the requests. Do you have ideas what can stops the pcm from servicing the SCISS requests. I will really like to get that fixed if possible. At least on lower rpms there will be plenty enough time for the pcm to handle communication.
    Hi,
    So my ESide does not use the sci, but GM seems to be big on code re-use. And why not, their code is very well written and tested. Perhaps this code snip will be of some use:

    Code:
    *************************************************
    * VECTOR AT $FFD6
    *
    * SCI INTERRUPT
    *************************************************
    4D8C  B6 10 00    	LDAA   $1000		; READ PORT A
    4D8F  97 7A       	STAA   @$7A		; SAVE IT 
    4D91  84 DF       	ANDA   #$DF		; SELECT FLASH BANK 0
    4D93  B7 10 00    	STAA   $1000		; 
    
    4D96  CE 10 00    	LDX    #$1000		; POINT AT REGISTERS
    
    4D99  1F 2D 20 09 	BRCLR  $2D,X,$20,$4DA6	; BRANCH RX NOT READY: SCCR2
    4D9D  1F 2E 20 2A 	BRCLR  $2E,X,$20,$4DCB	; IF NO CHARACTER, DONE: SCSR
    
    4DA1  BD BF 35    	JSR    $BF35		; PROCESS RX BYTE
    4DA4  20 25       	BRA    $4DCB		; DONE
    
    4DA6  1F 2D 80 09 	BRCLR  $2D,X,$80,$4DB3	; BRANCH TX NOT ACTIVE
    4DAA  1F 2E 80 1D 	BRCLR  $2E,X,$80,$4DCB	; IF TX REG NOT EMPTY, DONE
    4DAE  BD C1 2A    	JSR    $C12A		; PROCESS TX BYTE
    4DB1  20 18       	BRA    $4DCB		; DONE
    
    4DB3  1F 2D 40 14 	BRCLR  $2D,X,$40,$4DCB	; BRANCH COMPLETE NOT ACTIVE
    4DB7  1F 2E 40 10 	BRCLR  $2E,X,$40,$4DCB	; IF TX NOT COMPLETE, DONE
    4DBB  86 26       	LDAA   #$26		; SET FOR RX, WAKE MODE
    4DBD  A7 2D       	STAA   $2D,X		; 
    
    4DBF  CE 18 02    	LDX    #$1802		; IOR CHIP PORT B
    4DC2  1D 00 40    	BCLR   $00,X,$40	; DISABLE ALDL OUTPUT
    4DC5  15 7D 40    	BCLR   @$7D,$40		; UPDATE EXPANDER PORT A SHADDOW
    4DC8  15 7E 01    	BCLR   @$7E,$01		; CLEAR IGNORE MESSAGE FLAG
    
    4DCB  13 7A 20 08 	BRCLR  @$7A,$20,$4DD7	; FIND PREVIOUS BANK
    
    4DCF  F6 10 00    	LDAB   $1000		; RESTORE TO BANK 1
    4DD2  CA 20       	ORAB   #$20		; IF PREVIOUS 
    4DD4  F7 10 00    	STAB   $1000		; 
    
    4DD7  3B          	RTI			; DONE
    This is a commented section of code from TSide that is the interrupt service for sci.

    -Tom

  5. #185
    Fuel Injected!
    Join Date
    Jan 2019
    Location
    Canada
    Posts
    135
    Now that TPU's initialization problems are behind me (? i hope), I got a few things done this morning.

    I wrote bootstrap code that initializes the TPU and reads&buffers it's registers (all of them). The code then waits 12.5ms and re-reads&buffers the result. The results can then be moved into excel for analysis. I have done a bit of this and can see a number of the undocumented locations that are not used in the code. This gives me a better look at how the internal TPU code is working with the signals.

    While messing with the above code, I had a good look at the interrupt structure. While I still have no life on the ignition signals, I was able to get the interrupts to fire on the fuel side. That will enable me to understand all of the registers connected with fuel or at least I hope so. I will get back to this tomorrow.

    -Tom

  6. #186
    Fuel Injected!
    Join Date
    Mar 2013
    Posts
    791
    Thanks for the input on the SCSSI. After some trials and some bricks I managed to make the eside talk while the engine is cranking.
    First I tried to reenable comms at oc4i. It didn`t worked as expected. I ended oraa $20 to the SCCR2, which make the comms worked on a very rare random basis.
    I was tired of experiments and skipped the scssi disable code in the irq. This made the eside talk. It is not clear what will happen on a higher rpms, so I think to put a rpm threshold and reenable the comms at oc4i after the rpms drop. I will also cut all aldl chatter on the bus. I suspect the interrupt is activated on any aldl bus activity.

    I wish I have an opti simulator for testing. How hard will be to make one like yours with a knob to regulate rpms.


    The plan for cracking the tpu from the backdoor is solid. You can chart the unused pins ram locations and possible found more things left on the table from factory.
    Tpu and eside exchange data each run of the irq. Eside calculates cyl fire id and sends it back to the tpu. I also found some code used for loss of sync[cyl ID] situations and resync on the fly. Really good job from GM.

  7. #187
    Fuel Injected!
    Join Date
    Jan 2019
    Location
    Canada
    Posts
    135
    Quote Originally Posted by kur4o View Post

    I wish I have an opti simulator for testing. How hard will be to make one like yours with a knob to regulate rpms.
    You are welcome to the code on request. It isn't sophisticated and not finished in a nice way. Just a crude tool I knocked out to try and get an understanding. There is no "knob" to adjust RPM but it can easily be added. Do you have any dead PCMs? If yes, why not fit the code into the EEPROM and run it there. I think this was what was in my mind when I started things. My board is a tester from way back in the 1990s. It runs at 4MHZ but with 0 effort will just scale to the 12 used by GM.

    Let me know what you need, and I will post. Easy way to work will be through bootstrap. I can give code, instructions++

    -Tom

  8. #188
    Fuel Injected!
    Join Date
    Jan 2019
    Location
    Canada
    Posts
    135
    Good fortune this morning, I got working with the fuel side and started to characterize some of the parameters. I don't have a great scope, but it looks to me as if the injector pulse width defined in the 16b registers at $1400 - 0E work like this:

    GM's crystal frequency
    12.5829 MHZ
    12582900 HZ

    Resulting Eclock frequency
    3.145725 MHZ
    3145725 HZ

    Clock period
    79.473E-9 Crystal
    317.892E-9

    Injector pulse width for locations $1400, $1402, $1404, $1406, $1408, $140A, $140C, $140E
    n * 15.259E-6


    Still a bit of uncertainty if the divisor is 48 or 50. If I squint just right I can see one or the other. One of these days I need to trade up from my army surplus scope. I will bypass the drive circuits&FETs to measure and resolve this Q.

    Also got the ignition to fire this morning. Real happy with that. On we go...

    -Tom

  9. #189
    Fuel Injected!
    Join Date
    Mar 2013
    Posts
    791
    That is some great breakthrough. Now can we find out what is the usage of high res signal. Is it only used for spark triggering or it does affect fueling also.
    Cranking is really hard without high res signal but that is because the pcm needs some cranking before setting the code. I also traced some tpu bits changed on the error.

    The pcm outputs 5v on low and high res pins and the opti drives the signal low on empty slot I guess.
    The simulator should be pretty easy if I had a spare pcm.

    n * 15.259E-6
    That scalar is used for all time based units in the tpu. It will be nice to confirm it. Now it is something more of a guess based on Gm conversion data of bpw.

  10. #190
    Fuel Injected!
    Join Date
    Jan 2019
    Location
    Canada
    Posts
    135
    Quote Originally Posted by kur4o View Post
    The pcm outputs 5v on low and high res pins and the opti drives the signal low on empty slot I guess.
    The simulator should be pretty easy if I had a spare pcm.
    I thought you might already have what you would need. Otherwise, almost any of the single board computers available for a few $s can easily do. It is logistically easier if the part is 5V based but almost anything will do. Doesn't need to be Motorola at all. A PIC or an old intel 8051/31 type board would be ideal. In fact now that I think of it... your PC could output the pulse train through a parallel port under dos. I wouldn't want to use windows/linux/some big OS because the timing will be un-steady due to latency. Also the larger OSs might be slower and limit "RPM". Even so, you could try it under windows and see if it meets your need.

    -Tom

  11. #191
    Fuel Injected!
    Join Date
    Jan 2019
    Location
    Canada
    Posts
    135
    Still working on TPU but,

    I have a question regarding MAF. My understanding is that the MAF unit produces a frequency that is interpreted by the TPU. Is the frequency proportional to air flow or air flow mass? I know mass will be affected by temperature (IAT) and pressure (Barometer) the question is, does the MAF unit factor all this in or is it actually a measure of air flow and uses software to come up with the mass rate? I think the MAF might be mis-named (?)

    If anyone can provide some clarity it will be a help.

    -Tom

  12. #192
    Fuel Injected!
    Join Date
    Mar 2013
    Posts
    791
    Maf is a mass air flow, It measures mass with a heat element being cooled. It is supposed to compensate for temperature and pressure, however humidity kind of screw the reading. However in the code there is only baro correction and some temperature correction for subzero temperatures. The corrections might not be output related but different engine requirements at that range.It also updates so quickly that gm put some smoothing routine to compensate for rapid changes.

    The TPU outputs 4 maf values and eside gets an average of them for final calculation. It uses the raw TPU output for a maf table lookup and takes the value from table and interpolates between 2 adjacent cells. The first byte of RAW output is the vector for the table lookup and the second byte is the interpolation factor 0-255 or 0.01-0.99.

    I will try to find a 68hc11 pcm to run a custom code for opti simulation. For variable rpm output I think a table for 1 high res pulse vs time vs rpm needs to be done and low res will just follow the high res.

  13. #193
    Fuel Injected!
    Join Date
    Jan 2019
    Location
    Canada
    Posts
    135
    I took a deep dive into injector offset. This parameter is set in the TPU at address $14B2. I believe the calculation goes like this:

    -Read ignition voltage from A/D ch0
    -Apply a transfer function to the voltage value such that points on the table are further apart under abnormal conditions and close together in the normal working area
    -Transfer function is then used in an interpolation routine
    -The output is an 8b value, a 16b value is developed by multiplying by 2
    -That 16b value is the one applied to the TPU

    Given the table for a '97 Z28, this is the stock graph. PS... missed some of the graph. Red is transfer function, green is injector offset. Decimal point missing in the voltage...
    InjectorOffset.jpg

    I plan to try various values for offset to determine how this is applied into the calculation of end of injection and/or pulse width. More work is needed on my end to understand when this parameter is calculated. I see it done in at least two places with code that is for the most part the same. Not sure why it is duplicated.

    -Tom
    Last edited by Tom H; 1 Week Ago at 10:28 PM.

  14. #194
    Fuel Injected!
    Join Date
    Mar 2013
    Posts
    791
    It is done at reset and than at oc4i.
    The update of offset value is every 100ms and it is stored at the TPU every 112.5 ms. I am sure it will be the same or close at the 96-97 code.
    It will be nice to figure how it is handled by the tpu. The 16bit value is converted to ms by the same factor for BPW and low res signal.
    I suspect that tpu adds the offset to the BPW before commanding the injector. Since you are at the injectors side, do you think that there is a setting in the tpu to fire injectors in batch mode. Does it use some average bpw value or still use the ind cyl bpw but fire 4 of them at the same time with the bpw set different for each cylinder.

  15. #195
    Fuel Injected!
    Join Date
    Jan 2019
    Location
    Canada
    Posts
    135
    Quote Originally Posted by kur4o View Post
    It is done at reset and than at oc4i.
    The update of offset value is every 100ms and it is stored at the TPU every 112.5 ms. I am sure it will be the same or close at the 96-97 code.
    It will be nice to figure how it is handled by the tpu. The 16bit value is converted to ms by the same factor for BPW and low res signal.
    I suspect that tpu adds the offset to the BPW before commanding the injector. Since you are at the injectors side, do you think that there is a setting in the tpu to fire injectors in batch mode. Does it use some average bpw value or still use the ind cyl bpw but fire 4 of them at the same time with the bpw set different for each cylinder.
    Thank you for the details.

    I wrote a simple test that writes a table of values to $1400 and $14B2. I believe $1400 to be injection pulse width and $14B2 to be injector offset. While monitoring the injection signal, I changed both PW and Offset. I looks like the two are added and the pulse width is the sum of both. Next is to measure pulse width vs EClock.

    -Tom

Similar Threads

  1. Tuner Pro XDF 1999-2000 F Body + Y Body
    By john h in forum OBDII Tuning
    Replies: 33
    Last Post: 3 Weeks Ago, 11:12 PM
  2. 94-95 LT1 $EE Y-body vs. F/B-body PCM differences
    By johnny_b in forum GM EFI Systems
    Replies: 4
    Last Post: 01-15-2019, 06:48 PM
  3. Replies: 31
    Last Post: 09-20-2018, 06:00 AM
  4. F-body engine install to B-body
    By serge_an in forum GM EFI Systems
    Replies: 4
    Last Post: 09-22-2016, 02:51 PM
  5. 95 F-body Fuel Pump with 95 B-Body Engine/Tank
    By EPS3 in forum GM EFI Systems
    Replies: 7
    Last Post: 09-19-2016, 02:40 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •