I recently switched my turbo 60 degree V6 application 730 ecm, from the 8F Turbo Grand Prix code to code59 after rearranging the harness. Although not completely tuned and road worthy before the change, the car cranked and ran consistently and had reached as high as 7psi.

After the wiring and code change, the engine cranked and ran harmoniously for about 2 seconds repeatedly, giving off a few small pops and flames before stalling out.

I connected the Moates APU-1 and noticed that the engine would move towards stall just as the timing advance count started to increase. The TPS sensor was wired backwards due to a difference between the round terminal and flat terminal sensor assignments. Coincidently that was during the first start attempt and the engine struggled and ran longer with that fault than it did after it was corrected.

After it was corrected it dropped to about 2sec run times. I also found with a timing light and oscilloscope that the coil packs were firing intermittently which made no sense and the crank position sensor(still new) produced an abnormal waveform. While looking over some wiring diagrams I discovered for the first time that the CPS sensor wires are to be twisted together not less than 9 times per foot, they had been unwound during the harness change and clean up.

You are probably aware by now that the problem is with timing constants in the code. I changed the ref angle to 59.8 deg which is the constant for the DIS V6, but apparently that is not enough. The car is at home nearly 500 miles away and it was after leaving that I discovered the following constant mismatches:

________8F DIS vs. 59 distributor
Max adv_ 80.16 __46.76
Max ret __20.04___ 0
Ref ang __59.8____ 0
Initial adv_ 9.1 ____?

There are a few other addresses in code59 that I was not able to find in 8F: ESC max retard 24.96 for example so I'm not sure that making the changes to code59 to match the 8F values in the tables listed above will be enough to fix the problem. It appears the timing is being retarded to the 59s 0 deg.

I don't have much time between school and work to get back home and work on it but need it running soon. Its been down for a year and a half due to the swap.

Any help in solving the problem would be greatly appreciated.

86 Pont Fiero, 07 3900 V6, 06 6 spd transaxle, twin T3s .60/.48.

 

i'm guessing you have already asked over on the 59 board and read this link. but i figured it couldn't hurt to repost it anyways

http://www.diy-efi.org/twiki/bin/view/Gmecm/DISdist


good luck. looks like a fun setup to drive

 

Thanks, I reviewed that write up a while back, but it comes across as more suggestive than definitive to me. I need a little more detail for a firmer grasp of what exactly is happening particularly regarding a negative value for a timing constant.

An old thread I found that was written up by Grumpy regarding timing logic is excellent, however, it does not clue me in on the negative value proposed for a DIS system either.

It did take in a step by step approach to delivered timing involving other tables that take part in the logic calculation making me aware that more values are involved than what was listed in the twiki briefing.

I also received input on the code59 forum suggesting a max retard value in 59 of -70 deg although for the DIS code 20 was listed. Perhaps it's a formula difference associated with a distributor system.

 

i'm still hoping to convert a v8 in the next few months. so i hope i have a easier time than you seem to be having.

have you tried asking over on the diy side. i'm pretty sure more than one person is running it. i also belive that "Hudini' on the 59 board has a setup close to yours that works right.

 

I know of no one that is successfully running code59 with DIS ignition. turbodig one of the editors of the code on the 59 forum helped me out but I was still unsuccessful and just finished reinstalling the harness after repinning it for 8F Turbo Grand Prix code which it ran successfully on.

Hudini to my knowledge has not made in headway either since the last time I was in contact with him. Code59 is very impressive and I hopse someone succeeds in getting it to work with DIS so I can switch back to it.

Right now I'm trying to shake the fear of the engine still not starting eventhough I've returned it back to 8F code in order go make an attempt.

So far I drained the old fuel, regapped the plugs to .035 which is more OBD1 friendly and checked compression which is above 212 on all cylinders. If it doesn't start I'm not sure what could be wrong.

 

^ Try reaching out to Six Shooter & junkcltr, they will more than likely know for sure....

 

Six Shooter provided me with the most help up to this point. However the problem still persisted up until yesterday when I converted the harness (one wire change) back to 8F code compatibility. The engine runs great so far although after the code change it took some effort to get the engine started, once that hurdle was cleared it started and ran consistently so maybe it will be more responsive to future attempts with code59 to figure out the timing mismatch if one really existed as opposed to a possible error somewhere on my part.

To date I don't know of anyone running code59 with DIS ignition.

I'm about to start putting everything together and installing intercooler plumbing in hopes of getting a test drive out of it today.

 

just happened up on this post. looks like atleast one person is running.


http://www.code59.org/index.php?opti...=5960&catid=12


sounds like kind of a around about what. but seems to work for him.

 

I'm the reason that information was posted, it was sent to me in an email first in response to a question about what he did to get code59 to work with his ignition system, it cleared up a lot, especially the bias spark table needing to be set to 0 to actually advance the timing. It's a very definative explanation.

Thanks for the heads up though.

 

What is happening, particularly, regarding a negative value for a timing constant is that the area between the maximum and minimum constants must not be outside the range of the values typically expected as the result of the equation "desired timing minus reference angle equals delivered timing." If you need a graphical representation of the values typically expected for your engine, make a 3 column chart with the first column labeled "desired timing" and numbered from 0 to 60. The second column should be "reference angle" and in your case should be 60. The third column is "delivered timing" and contains the result of column 1 minus column 2. All but one of the values in column 3 will be negative, with the greatest value (most positive) being 0 and the least value being -60.

The TWIKI specifically mentions reference angle, max advance, and min advance (max retard). Changing the reference angle alone is not enough.

You've been bamboozled. The magnitude and sign of the $8F numbers are not correct Why? The timing values are 16 bit numbers but many of the earlier distributor calibrations ignored the upper 8 bits. It may have started a convention among the early tuning software and hac authors to only read / modify the lower 8 bits. Worse yet, it would likely get even more confusing if $8F were to show max and min timing values as negative numbers.

The max and min values are based on the ignition system and the physical limitations of the engine. They are not in place to prevent tuning errors, but to prevent major catastrophes. You can adjust them closer to the range of timing values you expect to see, but GM does not use them in this way. The easiest way to get the exact values GM used is with a hex editor to view / copy the values directly from $8F into $59. Remember they are 16 bit twos complement numbers, so they will begin with $FF. In $8F they are located at $001D and $001F and are $FFE4 and $FF39, same as those on the TWIKI.

To calculate your own, you can use this method:
Desired limit(decimal) * 256/90 = engineering unit (decimal)
engineering unit (decimal) = engineering unit (hex)
$FFFF - engineering unit (hex) = limit value for calibration. It's about 256/90 off from exact, but it will work with windows calculator in scientific mode.

Also keep in mind that the "max retard" and "max advance" values have to fall on the outer boundaries of the typically expected values from the result of "desired timing minus reference angle equals delivered timing." For a reference angle of 60 degrees and desired timing of 0 to 60 degrees, the maximum value found is 0 for 60 degrees advance and the minimum is -60 for zero degrees advance. Also note that $58 does not use an "initial spark advance" value. As this value is 10 deg in $8F, I believe it's not a bad idea to set the max at 0 and the min at -60.

HTH

 

Thanks for the input, I've also received other valid guidance that I've not been able to put into play as of yet but plan to do so at a later date in favor of switching back to 59.