True, bug there are some ignitions in range three as well that happened at the same time.

 

It's been documented before though that an aggressive run that hits the rev limiter with readings in ranges 1 and 2 can spill into range 3 - 4 ignitions in range 3 seems more a rev limiter issue than a mechanical over-rev (mis-shift).

 

In your reply, Why do you use 3 ignitions per rev instead 6 per rev, one per cylinder.

Bob D

 

visualize the engine running and you should be able to figure it out - you can't have all 6 cylinders firing on 1 revolution.

 

3 ignitions per rpm at 7200 rpm's = 21600 ignitions per minute
Dividing that by 60 seconds = 360 ignitions per second
The ignition event at level 3 was recorded as lasting for 4 ignitions which lasted 4/360 th of a second or .01 or 1/100 th of a second using 7200 RPM's as the number of RPM's reached.
As the RPM's reached at level 3 are higher than 7200 the time factor is less than 1/100 th of a second and so small as to be irrelevant.
Someone please correct me if my math is in error.

 

3 ignitions per revolution NOT per rpm...so there are 120 revolutions per second (7200 rpm divided by 60 seconds) therefore with 3 ignitions per revolution at 7200 rpm you get 360 ignitions per revolution NOT per second. That's the extent of my math knowledge

 

bottom line. ppi and buy. DME is perfectly good!

 

Just out of curiosity, where has this been documented?

 

Wish I could remember and provide a link but it was a response in one of the hundreds of discussions about DME and over-revs over the last 4+ years. IIRC, it was a response by one of the tuners who frequent the forum...maybe Scott Slauson of Softronic...but then as I said I don't remember exactly. Maybe someone with a better memory will respond.

 

I know that some one posted a readout that showed a total of 3 ignitions at level 3. The general consensus was that this is not mechanically possible and was an artifact of the limiter response. Btw, is it true that OP unsubscribed from this thread?

 

Go thorough a careful PPI. DME report looks fine. But you should check everything else.

 

Deal fell apart. Dealer gave me the service records they had and pulled the deal after I asked questions following the review of the records. Said I'd never be satisfied. Oh well...there are many other cars out there.

 

That sounds like there was something sketchy going on. Best to move on anyway.

 

Dadio's math is what I have heard. 360 ignitions per second in a range is a good rule of thumb. That was a good report. Not even two seconds on range 1 and a fraction of a second in range 2.

 

Sorry but it's 3 ignitions every revolution so the number of ignitions per second would vary by rpm - e.g., at 7200 rpm there are 360 ignitions per second but at 6800 rpm there are 340 ignitions per second and at 8000 rpm there are 400 ignitions per second. The overall conclusion regarding this report won't change since we're talking about milliseconds but the 3 ignitions happen every revolution not every second.