DRP interval

[Chas54]

Ive noticed that on my elanscan traces, the DRP interval wnaders about a bit. Its a measure in milli second but I don't know if it is significant or not. Im trying to sort out my occasional engine revs dipping when stopping problem. The ignition advance also seems a bit erratic.
Anyone know what the DRP is?

[Chas54]

I think now it might be Distributor Reference Pulse.

[GeoffSmith]

'tis. It makes a lot more sense if you plot the data against engine speed on the X axis. It makes even more sense if you plot 1/DRP!

[Chas54]

Thanks Geoff.
That's a very satisfactory looking curve. I wondered was this plotted within Elanscan of did you plot the DRP reciprocal using Excel?

I was looking at a raw data curve , but I now think I may have to convince my windows 10 PC to allow me to use my ancient Office2003 Excel version.

Thanks again
regards Charlie

[dapinky]

....but I now think I may have to convince my windows 10 PC to allow me to use my ancient Office2003 Excel version.

Bloody modernist!

I still install Office '97 as a default on most machines.

[GeoffSmith]

You can select engine speed for the x axis within ElanScan. The reciprocal was plotted with Excel 2003 on W7.

[Chas54]

After some messing mangaged to install excel,

Looking at my data i've noticed the ignition advance when idling wanders about and this corresponds to my drop in idling speed. The drop is sometimes to 925 and intermittently to 900.

Cant see anything wrong with MAT , MAP , Coolant temp or engine speed sensors , and the knock sensor never shows anything except zero, knock retard shows the same zero.

I Have taken the cam timing device off for a look but there is very minimal play in the reluctor disc corresponding to the play in the drive slot pin I think.

I am no wondering if the Zero reading from the knock detection is causing the ignition advancing and retarding during idling. I know the knock detector retards the ignition when it detects late detonation and then advances it again , but with having no knock registered, could it be doing something anyway?

I am awaiting a new IAC after roving mine and finding it very shiny on one side and pitted on the other at the valve face, I might see if I can get my hands on the Knock sensor whilst I have the bonnet off.