The weather broke today and temps got up to ~40* today, so I unbagged the max, connected my laptop (with datscan 1.52) to the Consult port, and went for a drive to try and log a WOT run, just because I could and the sun was shining.

Attached is one graph showing a WOT 1-2-3 street pass, with RPM and Timing on the graph. I was surprised to see so much variation in ignition timing before and after the WOT pass. Is this normal ??



Another view..



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Nobody sees a problem with the timing fluctuations ??

 

I see a problem with your timing AND rpm fluctuations. When I run this program on my car or when Im just watchin it on streetz' car its a smooth line for both timing and rpm...

Look Although I was not about to export the graph, I just wrote down the values and I put em on an excel graph back when I was trying to figure out the timing differences bet'n MAFs and correction settings. This is what that looked like....

 

Hey, thanks for responding.. The time span of the top chart is for 10 minutes or more of street driving, just compressed into a short graph. There is a slow-roll, then WOT with a automatic in stock mode so shifting at 6400 RPMs through first, second, and into third up to 90 MPH or so, with one let-off of the throttle when the wheels spun in third. The bottom graph shows a shorter chunk of the same WOT run, so fluctuations are much less.

Remember, this car is cammed up and doesn't like to idle below 1000 most times.

The timing, however, looks weird. During the WOT run, it was stable around 23*, except where I let up for an instant, but just driving around shows a wide span of ignition, from 0* to 47* advance. I thought maybe a flakey cam or crank sensor might do this, but no codes.

Maybe when today's snow melts off I can do more digging..

Thanks again.
EDIT- if this graph is correct, I should be able to connect a timing light to a plug and see the timing fluctuation at the marks on the crank pulley, right? Kind of a sanity check for this apparent timing flutter..

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Your timing looks fine.

It is pointless trying to compare timing with other people at anything other than WOT conditions.

At idle, your timing will be around 10-15 deg.
At cruise, (steady throttle pressure) it will be in the neighbourhood of 35-45 deg.
Anytime you are decelerating (lift off throttle), your timing will go to approximately 0.

At WOT, you will be in the 20-30 range.

 

a so its 10min compressed into the graph! ok now it makes more sense for it to be jumpy like that. My records started when I'd go WOT and end when I let off.

 

Thanks for the feedback - that's about what I'm seeing when the charts are examined in small increments.

More interesting, on the blaZt forums, there is a discussion of the Timing measurement that is exactly backward from what I thought it meant.

http://www.blazt.biz/forum/viewtopic...a847a55b3bc035

These's lots more, but "Yes, nothing can show your actual timing except a timing light. " is a quote. Apparently the Timing graph is a representation of what the ECU thinks the timing should be, not what it is.

Guess it's working OK - WAD.

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It depends what you are using to monitor timing with. If it is through the OBD-II or Consult port, then yes, you get what the ecu believes it to be.

However, if you are monitoring the ignition pulses directly (ie oscilloscope, EU, UTEC, etc) then you get what it actually is.

Unless you are strappped down on the dyno, monitoring timing with a light during a WOT pass may be a little hazardous.

 

I'm using Datascan, through the Consult port - hence the Datascan graph in post #1. But you bring up a good point - how to monitor and record Actual ignition timing ?? WOT or normal driving, an underhood timing light is no help at all. All crank/cam sensor triggers and ignition coil pulses are on the ECU in the cabin, but the signals would require something extra to interpret the ignition advance from those signals. I wonder if there is an existing box that can do it ?

Google-time...

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