how to fix late ignition timing

Hi this is Frz auto from how EFI works comm  and today I want to talk about spark  latency this is one of those things that  you very seldom see talked about on the  Internet, and it's amazing how many Tunes  that people send me that this has never  been set the symptom you get when you  have a spark latency problem is your  timing changes are floats as you rub the  motor and the timing is set to fix  timing in the software the cause is  ignition systems have a delay it turns  up with capacitors inductors all this sort of things in electronics there's  always some sort of delay this stuff is  not lightning-fast like you might think  I'm going to show you 

some maths the  boring stuff that gets involved in this  and then I'm going to give you some rules  of thumb on spark latency you have to note  that this must be set before dyno power  tuning if your tune has a zero in this  setting this was most likely never  checked in set by your tuner and never  blindingly accept an internet tune as  perfect this is one of the biggest  reasons you can often see six or eight  degrees of timing shift because somebody  never set this is a basic circuit  that you have wind timing a motor here  is your 

crankshaft spinning around this  particular one is drawn with four  magnets for example but more than likely  it's like thirty-six minus one tooth on  the crankshaft, and you have a set of  timing marks hopefully you have a set  for maybe 15 or 30 degrees, and you can  lock your timing in the software to the  same setting as you get at the  crankshaft you're in a crank sensor this  is a hall sensor typically or possibly a  VR sensor it could 

have some delay in it is processing its signal since it  off to the ECU where the ECU runs  calculations both hardware and software  there can be some delay in when the signal is sent to the coils to  charge up typically you're sending a five-volt signal to charge the coils  then release the five volts and off goes  the spark to the spark plug and the  timing light you can also see I've got  this drawn as a setback type timing  light or an adjustable timing light that  is the sort of thing that you really  want to avoid when doing base 

timing the  reason is they also have some delay or  latency this is the same drawing but now  I've added the cam and cranked off the  motor and on a typical Japanese motor is  very common we have a crank sensor up  on one of the camshafts well it turns up  that all this belt as it goes around is  using horsepower it is stretching a  little bit that's why we have this belt  tensioner and this also adds into the  total delay the higher the RPM the more  the delay in this case  so now let's do some basic maths a  motor turning 750 rpm 

that works out to  point zero eight zero seconds per  revolution of the motor or 4,500 degrees  of crankshaft rotation per second and if  you do the maths you'll end up with point  zero four five degrees per  microsecond now if we do the exact same  maths 3000 rpm higher we get 37 50 and  point oh one six seconds per Rev and you  go through the maths, and you end up with  point zero two to five degrees per  

microsecond so if we arbitrarily just  try the maths 165 microseconds delay  if that's what all this delay adds up to  you can see that your timing would be  seven degrees wrong at 750 rpm but a  full three point seven degrees is air at  30 750 rpm so in this particular case  we'd end up with 3 degrees timing change  given you have a hundred and sixty-five-microsecond delay as it turns up if you  have a fixed delay in your ignition this  number would just keep getting bigger  and in the case of 165-microsecond delay  you would have 

about six degrees air at  6000 to 6500 rpm so this can get to be a  big deal here's a rule of thumb if you  have your I said it's a thousand, and  then you rev it up to 4,000 at 3000 rpm  increase, and you look at your crankshaft  with your timing light and you see a 1  degree shift your timing changed from  say 15 degrees to 14 degrees that would  work out to 55 microseconds is the  adjustment you need to put in your  software and 

we'll get to that in a  little bit but if you see for example  three degrees of timing shift it would  take a hundred sixty-five microseconds  correction if you notice these two on  the right where you get into four and  five degrees change in 3000 rpm more  than likely there's something else going  on like your belt is seriously  stretching or something else  mechanically is going wrong in the motor  so be very cautious if you 

get up into  those numbers so what I'm going to do is  show you a few different software  packages where you find this it comes by  all sorts of different names in the case  of the mega skort world  it's called spark hardware latency the  easiest way to find it is going up here in  the search bar and then type in ignition  options and it'll bring up this and here  it is called spark hardware latency and  in this case, I've got 55 microseconds  

put in this is Holly's saw  where and if you go to this icon it says  EFI on it and go to ignition parameters  and if you happen to go to custom then  you can get to configure here in this  yellow box supposedly the rest of them  are already set I don't really know  and once that once you hit that box you  can see inductive delay at 40  microseconds right here in the yellow  box exactly the same setting they just  call it something slightly 

different  this is linked to g4 plus another tuning  software and there's a search function if you put in their ignition setup you will then see the ignition main and under their  ignition main you have ignition delay of 50  microseconds this is max ECU and if you  go under ignition settings and  here it is in the second slot down  ignition system delay again it's exactly  the same number as everybody else is  using this particular motor was set up  and found to be 40 microseconds is what  it took to get steady timing and motet  in one 

tune and if you go to all  calibrate type in delay, you'll find  ignition driver of delay and there it is  50 microseconds again that was the  setting for this particular motor to get  the timing stable last I want to  show you the Caltech software what you  do is go to the gear right here and then  come down to the trigger tab and you  have to turn on TDC offset angle table  enable this one is a little different  than the rest of them 

basically what you  do is the delay is essentially zero  degrees crankshaft degrees at zero rpm  but for example, if we found it 4000 rpm it took a four-degree correction to  get your timing to stay stable that's  what you put in and by the way, it would  continue to rise at that same rate all  the way up to the end of your power band  this one is a little more adjustable  than most and that you're actually  putting in degrees so in conclusion, the  goal is to get the timing at the crank  to match the timing as commanded by the  ECU it is 

best to check timing at the  crank with the ECU lot to fix timing  you should always avoid using a drop-back style timing light cheap tends to  be better than something in the $40 range  they're almost getting difficult to find any more ignition latency is called lots  of different names but can be corrected  in most all EFI standalone systems I  want to point out that if you're using  some sort of factory tune type system  you may not be able to find this setting  and if you go changing your coil packs, for example, you may have a problem 

you  cannot adjust ignition latency can  potentially come from several different  sources that all add up such as stretch  from your timing belts and ignition when  you adjust your ignition latency you  must later reset your base ignition  timing this is important for people  that want to see this in a little more  technical terms basically what we're  looking at is the red teeth or the red  trace is the 36 - one tooth pattern you  can see it 

here repeating where the blue  is your approximately three milliseconds  of dwell time that is charging the coils  and right here for example if you wanted  the spark to actually spark at the back  edge of this tooth this is the latency  correction shift you're doing what  you're moving is the dwell left to right  to get the timing to actually happen  when you want it to you can also see in  this where vertically it is voltage  coming from the hall sensor this  particular motor is coming in at about  eight and a half volts and down to zero  and you can 

see your dwell coming in from zero volts running up to about four and a half volts three milliseconds of dwell time the dwell drops hands slightly later the ignition flies these are the developers of the megawatt of your HD  it's the software I use to tune most of these motors and should you have the desire to help me stay motivated you can always donate at PayPal dot me slash how  EFI works and be sure to subscribe thank you for reading.