Been doing lots of datalogging as of late and lots of experiments with the timing tables..

Have one question:

Where is extra timing being added to what i have in the MSA (and ext.) coming from?

During cruising situations its adding roughly 1-2 degrees additional and under WOT conditions im picking up 30 degrees timing where 28.9 should be the actual?

Its making things kind if difficult to pin down knock and the like when im getting some added timing in there

Am i missing something or is something I'm forced to deal with?

All highway mode is disabled as well as EGrR functions...

Any thoughts suggestions welcome

Later and thank s
Jeremy

 

I had some mystery timing being added to the MSA too.
This is where my timing imputs where from.
"Base Cool Adv. Correction VS Load VS Coolant Temp"
Table.

and A test thats performed by the ECM at Coolant Temps above
95deg C Coolant Temp, Do a search and Check this thread out.
(Spark advance for coolant temp ? )

 

Which calibraton? Some calibrations have a 'low-octane" routine which pulls timing. While some add timing.

Also, watch your MAP values. I noticed that while on sea level the MAP sensor started to decrease from 100 kpa to 97 kpa as my RPMs increased. Because my spark advance has a higher value for 95 kpa than 100 kpa, it caused an increase in the spark advance as the rpms increased and the MAP sensor gave a slightly lower reading.

 

Nice seeing you have time to work on your won stuff.

If you want to pin down where it's coming from then set all the biases and tables to 0, and then one by one reactivate them to see what's going on. Slow and time consuming but gets to the nitty gritty.

That's also a reason to watch the MAx timing allowed value.

How's the drivibility?.

 

Just trying to isolate the max timing constant as well, may get the lady and have her drive while i use the romulator. Quick and easy way to zero and add a table at a time :-)


lol Just hate getting ever closer yet finding the nitty gritty details now that u get so close :-( it never stops lol


Will re-read my logged runs and see if what Glenn said may have any bearing(sounds like somethign to definitely look at).

I dont believe the coolant correction tables are having an effect at this point....between my cooling system and that wonderful Flow Kooler water pump, i dont have any coolant temp rise unless im doing sustained high speed :-) (will verify again however)


Driveability is actually pretty good as of late, with the cooler temps outside now im looking to start picking apart the open loop, cold engine driveability end of things....Im not happy so ill keep playing until i am (anyone got some information on that i would be more than grateful)

thanks and later
Jeremy
PS Bruce when i get a chance i will call u and u can beat editing code into me

 

doh forgot

Its a AUJP based $8D on my 91 Formula

 

Here are the timing constraints:

The max at L8026 is added to the inital value (in the bin) and that is the maximum timing that can be had. With the bin inital set to 6 deg (common) the max will be 48 deg.

The minimum is just that, the minimum timing allowed. Again the inital is added to it. These max & min values are defined by the distributor. The distance in degrees from one plug post to the next in the cap.

RBob.

 

Ahhhhhhhhhhhhhhhhhh interesting point Rbob hmmmm

So if mt initial is set to 8 and not 6 then i would be seeing an additional 2 degrees possibly ?


6+42=48

8+42=50

hmmmmmmmmmmmm Doesnt seem like that would be it, seem stoo blatantly straight forward .................

So setting the max timing constant 2 degrees less than what i have in the MSA(and ext) and maximum timing?

hmmmmmmmm


Shows the 42 as added to initial so the 8+42 =50 seems valid hmmmm and mine seems to be only off in the 1-2 degree range......... well if i get a chance i will try this latest theory out

we will see eventually(or im nuts)
thanks
Jeremy

 

If you are using TunerCat, the recent $8D definition has been modified to have the Main Spark Table include the base timing. Thus if you alter the base timing the Main Spark Table will assume that you ALSO have modified the distributor advance, and thus give you the same Main Spark. In the past, you needed to add the base to the Main Spark to get your total timing.

But, if you alter the base and it does not match the actual base, you will not get the proper timing the ECM is commaning based on the Main Spark Table.

For example, lets say at 100 kpa @ 4,800 rpm the Main Spark table is 28* and you have a base timing of 6*. The 28* already includes the 6* base and the ECM will add 22* of timing at the distributor. This 22* is the "relative timing" that will show on your scan tool and the 28* is the timing that will show on the Total Spark Advance on your scan tool.

As long as your base is truly 6*, then you will get your 28*. If you lie about the base and set it to 10*in the ECM but don't alter the distributor and leave it at 6*. The Main Spark Table will still show 28*, but only give the distributor 18* "relative timing", thus your REAL spark advance is only 24* (28 - 10 + 6). It will show 18* Relative Timing" on a scan tool and 28* Total Timing on the Scan tool. But you really only have 18* + 6 from the distributor.

Lastly, you need to add the amount of spark from PE less any retard from the Knock Sensor routine. This retard will not be accounted for in your TOTAL SPARK on a scan tool, but will be accounted for in the "relative spark advance" displayed by the scan tool.

There is now the "Octane Retard Routine" that also pulls timing away from the spark advance when knock in WOT is encountered and then slowly let's it return provide no more knock is encountered. You can seen these "Octane Retard" parameters on the Constants for $8D. I did a write up a couple of years ago on the "Low Octane Routine" that explains how to disable this routine. You very well may be encountering it as it tries to add spark back.

 

Im not crazy,(comma added for Leanne's benifit) just ignorant sometimes. Going back thru everything to pick it apart a table at a time , i did indeed have a goof i managed to miss repeatedly.

Was playing around with cold starting/timing/driveability and had moved my coolant table bias(constants) back to 18.3 and had not caught the fact that it had changed my entire coolant correction table by a +1.8 degree advance on timing :-)

Learn something new everyday :-( So i moved the bias back to 20 degrees and took away the extra timing and zeroed it back out and now all is happy in Formula land.

thanks guys
Jeremy

 

Good. Now you should do some experimenting with the "Low Octane Routine".