Did you ever just loose 10 degrees timing? Math?

[EagleMark]

10 degrees has been found! Comerz did it while emulating and data logging. Removed Altitude Spark Bias and instantly got 10 degrees timing in data log (and ran better), which now matches Closed Throttle Spark Advance table. Have not tested Open Throttle Spark Advance table.

He said truck would not start with stock memcal and no jumper. From data log this was a cold start, no start. This motor is no where near stock. Same bin file in both.

Now why? Why would altitude bias effect Closed Throttle Spark Table? Memcal jumper? We did check by running vehicle and unchecking CPI/MPFI with no results? Test may have been inconclusive?

Bin was BJYK that came with truck, converted by write ups to MPFI.
BJYK bias were not changed, lost 10 degrees as compared to other $0D TBI data logs.
Only bias changed now in BJYK is Altitude Spark Bias from 9.8 to 0.0 and got 10 degrees back.

Looking at a CPI bin there is no Altitude Spark Bias or Main Spark Bias.

Other change between CPI and TBI BJYK bin is BJYK has 0.0 MAT Spark Bias and CPI has 9.8 Mat Spark Bias, this is not surprising as CPI has a MAT and TBI does not.

Bins, data log, uploaded if anyone wants to look. Datalog is short, but can see immediate 10 degrees re-appear when Altitude Spark Bias was removed towards end. I've compared the 2.9 to 2.9.1 bins and only change is Altitude Spark Bias.

Bin has not been tuned and there have been some cheats for cold start issue that was probably more related to missing 10 degrees at startup, so there may be issues that need to be reversed.

I included my ADX and XDF with data tracing for spark ready to use.

[JeepsAndGuns]

I am not running any altitude spark bias, its set to zero in my bin. Didnt you say mine was missing this 10* also?

[EagleMark]

I am not running any altitude spark bias, its set to zero in my bin. Didnt you say mine was missing this 10* also?

Thought so, you added a lot. I'll look at your logs again.

[comerz1]

Mark,

The truck DID start with the stock memcal without jumper, just didn't run very well. I didn't run it long because I could instantly see the SA was still missing. Just wanted to clarify that for others reading as well. Also, WBO2 was showing around 10.XX, so maybe it was just loading up? Here is a datalog, which can be viewed with the adx that Mark posted in post #61.

stock memcal.xdl

Not sure I am getting attachment on there....

[EagleMark]

Mark,

The truck DID start with the stock memcal without jumper, just didn't run very well. I didn't run it long because I could instantly see the SA was still missing. Just wanted to clarify that for others reading as well. Also, WBO2 was showing around 10.XX, so maybe it was just loading up? Here is a datalog, which can be viewed with the adx that Mark posted in post #61


Not sure I am getting attachment on there....

There's still something strange about your timing with jumpered Memcal?

Looking at this log, timing was still short by 10, but it had immediate spark correction/change with Idle Spark Enabled Flag False, still timing was moving.

Looking at other log with jumper memcal, timing was locked at 16 until you changed Altitude Spark Bias, then it changed to 26 so we are not short 10. But timing was still locked, no adjustment until almost the end of log, when Idle Spark Enabled Flag came on it started adjusting?

[comerz1]

Could that have been because it was still in the cold start sequence? Everytime I have looked at data when I first start it, it takes a few seconds/minute for the idle to settle then the timing starts moving around. I just assumed this is the way it worked.

[comerz1]

Well I tried to edit my previous post, couldn't get it to work.

Anyway I just reread your last post Mark. My brain is fried today, took a minute for that to sink in. So idle speed timing kicked in right away with stock memcal, but takes a while to start flucutating with the modified memcal? See I just thought I was making progress again today and then my parade gets rained on.

I didn't change ANYTHING else. Simple memcal swap on the log I posted. On the log I sent you and you posted, the only thing I did was zero out altitude bias with the jumpered memcal.

[JeepsAndGuns]

Ran some errands this morning, when I got back home I checked the timing. It was at what I have programmed into the bin.

[dud]

I have an 8625 pcm and have tried several $E6 masks including BDJZ, BDKC and BDJY. Also tried $OD BJLH. Guess I had the same trouble with all of them. I'm green so I finally decided I just wasn't understanding something and that I was probably getting full timing even though it wasn't showing up in the logs.
Stumbled upon this thread, removed "Altitude Spark Bias" and WOW did my engine really come to life! I've tried many things trying to compensate for the lost timing that I really didn't understand I had lost. Had a lot of detonation at 80+ map & 1600-2400 rpms. Now it's pretty much gone. Never thought lack of timing would cause such problems.

[Kitch]

Is the "Altitude Spark Advance Correction vs Baro vs Vacuum" table the same thing as "Altitude Spark Bias"?

[dud]

Is the "Altitude Spark Advance Correction vs Baro vs Vacuum" table the same thing as "Altitude Spark Bias"?

"Altitude Spark Advance Correction vs Baro vs Vacuum" is a "Table". What you're looking for is a "Scalar". Go to Tools > Paramater Finder in TunerPro and do a search for Altitude Spark Bias. If you want to "Turn it off", set it to 0.0.

[Kitch]

I didn't think it was quite right, I'm using the BJYL-$0D-5.7-Auto.bin and a search for "Altitude Spark Bias" came up with nothing.

[Aksl]

Hi everyone, on my 5.7 Silverado Z71 1990, i have made a vortec heads swap, with all of the vortec manifold and CFSI system, as well as black box pcm/ecu, i left the original block, only changed pistons for KB flat top, left the original 4L60E transmission. Now my issue is that after puting this all together and making it run, i have misfires in the exhast, and by cheking with timimg light on crank, i misout 13°-15° earlier.
Another issue, is that i have not yet found, what exactly under the dash, i should conect to pcm/ecu (black box), and to what pins, for pcm to recognize the gearbox, becouse now it is not conected at all.
Sorry, forgot to mention that I have comp cam installed 08-467-8.
Thank you all in advance.

[sturgillbd]

I didn't think it was quite right, I'm using the BJYL-$0D-5.7-Auto.bin and a search for "Altitude Spark Bias" came up with nothing.

In Parameter View, Look under Spark Table Biases. Third one in the list.

[Kitch]

Thanks for that, found it.
So does that mean at sea level I'm getting an additional 9.8° added on top of whats actually shown on my main spark table or is it being removed as the thread title alludes to?

Aski, sorry I can't offer any advice about your question but you might want to start a new thread so that more people might see it.