ECM upgrade (1227730) for stock 2.8 (Page 102/107)
Darth Fiero AUG 07, 02:42 AM
Lots of new info so be prepared for a long read... (still working with the $8D mask)

RPM
Before today I was running TTS Datamaster $8D to watch and record live data with. I noticed in Datamaster that there were two RPM readouts: "RPM" and "RPM/16". The RPM reading was correct. The RPM/16 reading seemed to be 3/4 that of actual. I wasn't concerned with this at the time because the engine was idling where it was supposed to and changes I made to the fuel and spark tables were taking effect at the exact RPMs I wanted them to. However, today I had my GM Tech 2 scan tool hooked up and it was only displaying the 3/4 of actual RPM reading (which was displayed as RPM/16 on Datamaster). I did some experimenting with the rev limiter in the chip tune and set it to 3000 to test a theory. I revved the engine up to 3000, 3100, 3200....3500 - no rev limiter. The rev limiter finally cut in at 4000 rpm.

I did some digging in the "code" and found there is a FILTERED RPM and what I'll call a RAW RPM (seems to be a number displayed as "8 x 16" in the disassembly). The FILTERED RPM is the RPM all the major fuel, spark, idle, etc tables in the ECM use. The RAW RPM is what the Rev Limiter and probably some other minor functions like shift light and such use.

It looks like RAW RPM might have something to do with the engine running logic quoted below:


quote

***************************************************
* EST Minor loop
*
* Eng running logic
*
*
*
***************************************************
LB7B7: LDAA #0 ; CLR COP
STAA L400C ; CPU COP
;
; 8 cyl equiv RPM val
;
LDX #L00B3 ; CURRENT MNR LOOP DRP PERIOD
LDAA $8009 ; 0 = 8 CYL
BNE LB7C8 ; BR if Cyl NE 8
; .... else
LDD L00B3 ; CURRENT MNR LOOP DRP PERIOD
BRA LB7CB ; Save cnts
LB7C8: JSR LE33F ; No, scale to 8 cyl ref
; (8 x 16 MULT)
LB7CB: STD L0467 ; ECM IM RAM, NUM OF 65.5Khz cnts
; between DRPs
;-------------------------------------
; RPM, RPM P, RPM/25 & RPM/12.5
;
; Q = (153.6/RPM RER) * 2 ^8
;
; PER = 1/65.5 Khz per bit
;--------------------------------------
PSHB ;
PSHA ;
;
ASLD ; SET DIVIDE OPER
PSHB ;
PSHA ;
;
PULX ;
LDD #0307 ; 15 * (512/25) or 153.6 * 2
FDIV ; do division
PSHX ;
TSX ;
LDD 0,X ;
CMPA #96 ; 2400 RPM
BCS LB7E9 ; Br IF RPM <= 2400 RPM, (LO RANGE)
; .... else
ADDD #16512 ; ROUND Q & ADJ to HI RANGE (2400-4800)
BCC LB7F0 ; IF IN HI RANGE RPM/25
; ... else
LDAA #255 ; If > 4800 RPM limit to 4800, (255d)
BRA LB7F0 ;
;
;-----------------------------------------
; Mult by 2 in lo range, 1 bit = 12.5 RPM
; Round (2Q) and adj for lower range
;-----------------------------------------
SUBD #8064 ;
;
LB7E9: ASLD ; x2, RPM.12.5
BCC LB7F0 ;
; ... else
CLRA ; CLEAR RPM
;--------------------------------
; (-400 RPM ($20) + 128 to round)
; 0 CTS = 400 RPM
;--------------------------------
LB7F0: STAA L0057 ; RPM/25
PULA ; Pull RPM/25
PULB
PSHB
PSHA
ADDD #128 ; Round off
BCC LB7FD ; BR if no overflow
; ...




quote

*******************************************************
* 8X16MULT.SRC
*
* 8 x 16 Multiply with 16 bit result result rounded
* to the upper 16 bits.
*
* CALL WITH:
* A Reg = 8 BIT Multiplier
* X Reg = Adderss og 16 bit Multiplicand
*
* RETURN WITH:
* A Reg = MSB of 16 bit result
* B Reg = LSM of 16 bit result
*
* Exec time: 66 Cycles
* Code length: 20 Bytes
* Stack req: 3 Bytes
*
* ORG $E33F
********************************************************
LE33F: PSHA ; SAVE MULTIPLIER
LDAB 1,X ; GET LSB OF MULTIPLICAND
MUL ; MSB PARTIAL PRODUCT
ADCA #0 ; ROUND
PULB
PSHA ; SAVE PARTIAL PRODUCT
LDAA 0,X ; GET MSB OF MULTIPLICAND
MUL ; MSB PARTIAL PRODUCT
PSHX ; SAVE
TSX
ADDB 2,X ; ADD IN LSB PARTIAL PROD
ADCA #0 ; ROUND
PULX
INS
RTS ; RETURN TO CALLER
*******************************************************



If anyone knows how to fix this, I'm all ears. But from what I'm finding as I search the net for an answer, it does not appear as though anyone else is aware of the problem because they are only changing what I'm changing in the $8D to make it work with a 6 cyl and there is no mention of this other "RAW RPM" calculation or setting anywhere.


PE SPARK
Watching the spark advance PID on the scanner, when I go to WOT (activate PE mode), the spark advance dropped to about 20 and didn't go much above that. Knock retard is disabled (no knock sensor) so that's not the problem. Main Spark Advance table mirrors stock Fiero ECM tune settings which is 28.8 Deg Adv @ 4800 rpm and the PE Spark Advance Table also mirrors stock Fiero which is about +2 deg (added in PE mode) across the board. I'm not sure what is going on here but I went ahead and plugged 8 deg in the PE Spark Advance table @ 3200 RPM and 10 deg in @ 4800 RPM which resulted in a total spark advance of 27 - 31 deg at WOT / PE Mode at those respective RPMs - which is what I wanted.
TheKingOfBattle AUG 07, 05:10 AM
Darth-
Your post above confuses the snot out of me with all the technical details, but I guess that just means I have some reading to do.

Unrelated to the above posts, yet very relevant to the 7730:
I've run across these two threads on adding DIS on the stocker V6
http://www.fiero.nl/forum/Forum2/HTML/122002.html
http://www.fiero.nl/forum/A...110502-2-103834.html

I'm planning on building Gravitic Anomaly's setup, as I don't really want to tear open the motor. Would this require swapping code masks on the 7730 if I start my 7730 swap off running a distributor and then go distributorless?
I can turn a wrench, so please forgive my ignorance when it comes to the ECM side of the house, as I am new to the whole ECM tuning thing. I have been reading your threads, but I need to get smarter on some of the more basic concepts of computer tuning.

[This message has been edited by TheKingOfBattle (edited 08-07-2013).]

Darth Fiero AUG 07, 12:01 PM

quote
Originally posted by TheKingOfBattle:

Darth-
Your post above confuses the snot out of me with all the technical details, but I guess that just means I have some reading to do.

Unrelated to the above posts, yet very relevant to the 7730:
I've run across these two threads on adding DIS on the stocker V6
http://www.fiero.nl/forum/Forum2/HTML/122002.html
http://www.fiero.nl/forum/A...110502-2-103834.html

I'm planning on building Gravitic Anomaly's setup, as I don't really want to tear open the motor. Would this require swapping code masks on the 7730 if I start my 7730 swap off running a distributor and then go distributorless?
I can turn a wrench, so please forgive my ignorance when it comes to the ECM side of the house, as I am new to the whole ECM tuning thing. I have been reading your threads, but I need to get smarter on some of the more basic concepts of computer tuning.




Chet says he has run $8D with the DIS. I would like to hear some more details about how that worked out for him and if he has had (or still is having) any issues with doing that. While digging around for my most recent RPM problem in the disassembly, I found some stuff on ignition coil dwell. I do know that dwell time is going to be different between a 1-coil distributor system and a 3-coil DIS system. So I wonder if Chet was able to find the dwell tables in the $8D mask where changes need to be made to make it work right with DIS or if it really even matters (which it may not).

This is just one issue in a whole host of issues you run into when you try using something designed for one engine on another engine.
TheKingOfBattle AUG 07, 12:28 PM
Darth, thanks for the insight. I'm going to try it out. If I end up destroying the motor in the process, it's a perfect excuse to swap in a 3800sc.
sleevePAPA AUG 07, 01:07 PM
Its been done with $8D using N* coil, maybe even EDIS iirc...

http://www.thirdgen.org/tec...1-do-away-dizzy.html

http://www.thirdgen.org/tec...aujp-v4-setting.html
Darth Fiero AUG 07, 04:03 PM

quote
Originally posted by sleevePAPA:

Its been done with $8D using N* coil, maybe even EDIS iirc...




Using the $8D with a V6 distributor application has also been done before but there is a problem with it as I have discovered. And NOBODY else has said anything about it (at least none that I was able to find in my research). I mirrored exactly what "everybody else" has done in the conversion I just did and I found a specific problem outlined above. I just wonder how many people are driving around with problems they don't know they have. Not that it is a big deal; because, as I said, the "RAW RPM" reading isn't used by anything major in the ECM. But being the perfectionist I am, I want it all working 100% if possible.
Darth Fiero AUG 07, 11:41 PM
Ok, I talked to John at TunerCat and he told me what I assumed was "RAW RPM" really isn't. He said the scanner's definition file (both TTS Datamaster's RPM/16 and the Tech 2 RPM reading) assume the $8D system is always an 8 cyl application and what is being displayed is based on that calculation; and that's why I was seeing 3/4 of actual RPM readings on these scanners.

He also said the rev limiter setting in the $8D tune is based on distributor reference pulse period. The conversion equation for this is RPM = (65536 x 120) / (N * # Cylinders).

So, in a nutshell, we don't need to worry about the 3/4 of actual RPM "problem" and we'll just need to calculate the rev limiter setting any time we use the $8D code mask for a V6.
Darth Fiero AUG 09, 01:37 AM
I have a report from the customer. He said before he brought me this car that I just did the 7730 ECM swap using $8D in, the best highway fuel economy he could get out of it was 30-31 mpg. He said it now gets 35 mpg. This is pretty much a bone stock 88 GT w/ a 2.8L V6 & 5-speed getrag.

Highway mode fuel (lean cruise) is enabled in this tune. I've got it set up so it can only stay in highway mode fuel for 7 seconds at any one time. Then it must kick out (to give the ECM time to check the fuel trims) for 10 seconds before hwy fuel mode will re-enable. So that's 7 sec on, 10 sec off, 7 sec on, 10 sec off; etc etc etc. When I drove the car, you couldn't tell when the highway mode fuel was engaged or not unless you were looking at the scan data. The feel (power) of the engine did not change.
chetw77cruiser AUG 10, 09:01 PM

quote
Originally posted by Darth Fiero:


Chet says he has run $8D with the DIS. I would like to hear some more details about how that worked out for him and if he has had (or still is having) any issues with doing that. While digging around for my most recent RPM problem in the disassembly, I found some stuff on ignition coil dwell. I do know that dwell time is going to be different between a 1-coil distributor system and a 3-coil DIS system. So I wonder if Chet was able to find the dwell tables in the $8D mask where changes need to be made to make it work right with DIS or if it really even matters (which it may not).

This is just one issue in a whole host of issues you run into when you try using something designed for one engine on another engine.



Keep in mind that this was a "Few" years ago (2003) and I no longer have the car. I experimented on a 1991 corsica engine that was in a "project car" and had a manual trans and no A/C. With that said, the engine originally came with the 1227730 and $A1 code. I was in the middle of my tuning days and wanted to try something different. I used the $8D code because I was familiar with it. After a bit of experimenting and reviewing other factory bin's, I finally found the settings that allowed me to use the $8D code with DIS. Needless to say, the spark settings to allow this was the easy part. Fuel, spark, and other tables/settings had to be transferred or modified to get this mutt to run well. I only ran this for about a year before the car was retired do to a significant fender bender. During that time, I had no problems running the DIS with the code that was not intended for such use. The dwell code between both the $A1 and the $8D code function about the same, no settings need to be modified or to be found in the $8D. As far as the ecu in concerned, it is still controlling a single coil where the DIS module takes car of all the switching.

Here is what I changed to get this to work:

Spark Advance Initial from 5.98 to 59.77 for DIS
Spark Advance Max from 41.84 to -9.84 for DIS
Spark Retard Max from -3.87 to -69.96 for DIS

These may not make sense to most, but they do work.

If anyone is interested, PM/email me for a copy of the files.

Chet W.
Darth Fiero AUG 13, 04:51 PM

quote
Originally posted by chetw77cruiser:

Spark Advance Initial from 5.98 to 59.77 for DIS
Spark Advance Max from 41.84 to -9.84 for DIS
Spark Retard Max from -3.87 to -69.96 for DIS

Chet W.



Question: When making the above changes, is reported spark advance in the scan data correct (actual) or not?