How is the DRP value calculated?

 

ok, let me see if i did this right, this should be how its done.

16 bit counter, provides 65536 bit counts per second. to get DRP, you must know your rpm, so the conversion is from minutes, so you've got

65536counts/sec X 60 sec/min X 1revolution/4 ign events(8cyl)=

983040/RPM=DRP for 8 cylinder.
1310720/RPM=DRP for 6 cylinder.

this is based on 32B/6E stuff.

 

Hmm... now I gotta wonder which is right -

TunerCats got back to me, and told me it's 60/3*rpm for the V6, or 60/4*rpm for the V8....

Who's correct?

 

You guessed it, both are right!!!

jwscab shows DRP in units of timer "counts". (And, if I might add, in a very nice dimensional analysis format!)

TunerCat shows DRP in "seconds". To be clear, the equation for V8 is : 60/(4*RPM). It is NOT (60/4)*RPM. The RPM term needs to be in the denominator. As RPM increases, the time between pulses decreases.

To convert between the two, multiply/divide by 65536 counts per second.

 

thats part of the formula i gave you. I dunno if he's not taking into account the counter parameter. I also don't know how the code you are looking at does it, what kind of value do you get for a drp running that v-6 code? say at like 2000 rpm?

 

60/(3*2000) = .01 seconds. Could also be, that I'm looking @ DRP as Distributor Refernce Period, not Reference Pulses - I'm using it in conjunction with the MAF values to figure LV8 in the 302 ecu.

 

Itll be the dist. reference period, or the time in between each recieved reference pulse/cylinder firing. The actual time in seconds is the period multiplied by 15.26 &#181sec/bit.