*SOLVED*SPARK RETARD AS RPM INCREASE

[ZOOMZOOMs]

recienprendio.msq

As stated, spark retard as rpm increase, checked the obvious distributor locked, timing locked , correct reluctor polarity...
is a heavy retard, maybe 30 degres from 800 to 2000 rpm.
car formerly works nice, it seems to happen after the latest firmware reflash, tried to reuse old firmware, but find impossible to load it! ...very strange behavior..
engine is a chevy bbc 496 , uses locked up dizzy from msd (i know is not usual, but i use this setup a lot, with very good results, )and a msd 6a to trigger the coil... i even try using bip373 and direct coil control, thinking that the fail may be caused by the msd.

now the car is on direct coil control mode , triggered from pin7 of the procesor socket
attached failing msq and the last good working

sparkcrazyretard.msq

msq

i´m looking for ideas and suggestions, because this is a new and completelly unusual fail to me

[slow_hemi6]

I looked at the MSQ and saw you have a trigger angle of 108 degrees. That doesn't seem right on a V8 distributor as there is only 90 degrees between reluctor points and H/T towers. So 108 before is actually 18 before on the preceding H/T tower. 18 before is also in the disallowed trigger angle range. I am wondering if all this is what is causing the timing error. I would try to set it up with a trigger that is in the allowed range probably 10 to 12 before. Always make sure your rotor phasing is good when using a distributor.

[Paul_VR6]

Double check your output edge settings. Timing wander with rpm is usually inverted output.

[ZOOMZOOMs]

the 108 number, is just casual, i tried at 97 , and check and double check dizzy phase, this is a usual set up for me... on the other hand, i tried the spark output low, because i think the same about drifting spark.. but it does not help.

but!! using tthe same msq i changed the spark output to tacho out, only in the software, so i supossed that there´s no chance to have spark, or start the car...to my surprise the car starts, and have very retarded spark, that is not affected by the trigger angle...

what i think is that i´m having the real spark output signal, and a phantom one... that mess my timing... but dont know what causes the "phantom one" i checked my i/o pins usage, and nothing seems odd...

any suggestion would be appreciated!!! thanks a lot!

[ZOOMZOOMs]

so.. after a lot of try and fail, i decide togive a chance to my own car ecu, a first gen ms3x that uses fw 1.2.4 (the same that the troubled ecu use to have) and call a restore point from the old f.w, and now it works as it should.

i tried again to load the 1.2.4 fw in the troubled ecu, but found impossible to make it....

anyone can explain, what changes in the new firmware that could cause this?

[billr]

Are you saying that once 1.4.1 is in the MS you can't go back to 1.2.4? Why try, why not use 1.4.1 in both of them? Then you will have (the latest) "apples-to-apples" when comparing how it runs with the two ECUs.

[slow_hemi6]

From the Release note that come with the firmware.

6. Serial protocol
The firmware now uses the "newserial" protocol. This requires
compatible tuning software and firmware loaders.
(Note, it you want to revert to an older firmware version you will need to use
the new firmware loader, or use the boot jumper.)

[ZOOMZOOMs]

thanks a lot!! i miss that info!!! now i can play with all the fws!
well my last report was optimistic! but after a little work in the idle ,the drifting spark return... so i work hard all the day trying to isolate the problem and have a few finds:

i can lock the timing and the timing goes static if:
the rpms are over 1500 rpm and/or (still isolating this circunstances) the tps over 8-10%
when i lift the throttle the timing keep on the spot for maybe 1 second, after that it slowly (takes maybe another second and a half) advances 35 degrees more
if i accelerate again, it keeps advanced for 1 second, and then slowly retard to the spected advance, where it keeps spot on as long as i dont let it idle again.

maybe is a long time problem, but never diagnosed, because this car formerly use a very aggresive cam, and idles above 1200 rpm wish may hide the fail!!

up to date i try, 1.2.4 , 1.3.1 ,1.1.2 and 1.4.1 fw without any noticeable improvement
use msd 6a triggered via tacho out (as stated in the manual)
use direct coil control with bip 373 triggered by led spark (connected to pin 7 of u1)
try two diferent ecu´s with all the mentioned fw variants, and all the polarization and edges of capture possibles
the only thing that never touched is the distributor, but i already checked to keep locked and rechecked the phasing like a 1000 times!

but can´t imagine what kind of distributor problem can cause this.

thanks to all for the support !!

still open to any ideas!!

[billr]

Have you made a dizzy cap with a hole in it, to use a timing light to confirm the spark is drifting relative to the dizzy rotor?

[ZOOMZOOMs]

off course.. i have a modified cap... as i said earlier in this post , this is a regular installation for me!

[jsmcortina]

I looked at the MSQ and saw you have a trigger angle of 108 degrees. That doesn't seem right on a V8 distributor as there is only 90 degrees between reluctor points and H/T towers.

I agree with the above, that won't work.

James

[ZOOMZOOMs]

early this morning, i rephase de dizzy (msd pro billet) as suggested in the instructions from diyautotune, now it works at 10 degrees trigger angle... same problem

[Matt Cramer]

Now that you've got the right trigger angle, increase the spark latency number until the timing is correct across the board.

[ZOOMZOOMs]

Thanks for your suggestion Matt! but is a lot of drifting , to be corrected by hardware latency...
i tried, but as xpected it wont work.

the think, is that i can lock timing, and it won´t move , stays spot on, as long as the rpms are over 1500 rpm.. but if i let it idle.. it slowly advances around 35 degrees!!
is not a switch situation, because i can see how much it would advance step by step by 20 or 30 flashes from the timing light... and can hear how the idle deteriorates to a over advance hunting mode!

today i giveup and decide to check the timing gear, find everything o.k but decide to install a trigger wheel because now is easier having all the pulleys and damper removed... hope to have better news tonight!

thanks again!

Juan

[ZOOMZOOMs]

well this morning with everything dismantled, i tried to check the cam (roller mechanical) for end play...nothing(maybe because is hard to move the cam with the heavy springs working over the lifters i tough)... so i decide to remove the cam gear and check physically how is the torrington seating... surprise!!! the torrington is not even close to seat at the block!!! this is a l21 block, and supossed to have a wear plate bolted to the block that the torrington uses as a base... the people that build the engine forgot about it!!! there´s almost 5 mm end play at the cam, that can explain the spark drift at low oil pump effort!!! (idle) ...

maybe in another hour (6:30) we hope to test it!! crossin fingers now!

thanks to all for the help and guide!!

update!!! 7:40 pm spot on spark now!!! triggering from dizzy !

[billr]

You should have detected that "cam walk" by shining the timing light through the hole in the dizzy cap. I guess I should have given more details when I asked if you had a cap with a hole... If the dizzy rotor "stays put" relative to the cap (locked dizzy!) but the crank moves relative to it's pointer, then there has to be slop in the connection between crank and the dizzy.