I have both Tunercat and LT1_Edit.. unaware of the IAT vs Timing table... I'll look for it though.

20-25 should be good

I wanted to try the wideband 02 wired to both 02 inputs havent tried it yet, yes VE master uses feedback from the 02's (lterms or sterms) Good luck!

 

I just checked my LT1_Edit and cannot find IAT table. Besides, I think this would only take away timing based on hot air... not increase timing from hot air (hot air = boost). Just my thoughts I could be totally wrong.

 

I see where you are coming from. Hmmm guess my friend was full on shiiiii. I sent tc a link to this thread yesterday let’s see if he gets back to me. Since the increase is not constant i would assume that its not a table vs rpm that we are lacking but a table vs some sensor. But who knows it could be an algorithm of some sort. Im hoping he gets this one hammered out too. Cause im looking to run 14-18 deg of timing on my stock motor. I don’t need something like this being responsible for popping my motor.

Could i convince anyone else to email tc too?

 

Does that help anyone?

Maybe since were using a 2 bar map the egr is kicking in cause it see's map ranges for part throttle. So it advances the timing.

 

I got the same email from TC. EGR could be doing something, i did see it throw in 5 degrees in the past but I disabled it. Also, the MAP scale doesnt apply since we are simply halving the injector size, plus this is also happening to 1bar users correct? There's some posts below of people with 1bar having the same problem.

Hi Dan,

I'm not sure what might be causing the discrepancy in the spark advance values. Assuming the engine is up to running temperatures and the startup spark parameters are no longer active, the spark advance is derived from the 'Main Spark Advance Vs. RPM Vs. MAP' (or the 'Extended Spark Advance Vs. RPM Vs. MAP' above 4000 RPM), the 'Spark Correction Vs. MAP Vs. Coolant Temp.' and the 'EGR Spark Advance Correction Vs Vacuum Vs RPM'. Any knock retard or traction control retard values are applied and the values checked against the min and max spark values.

The spark advance vs. IAT table was not implemented in the LT1 cars until 1996. The OBDI calibrations do not have this table.

Make sure you don't have any error codes set. Sometimes error codes can result in strange behavior where default values are used instead of the normal values. The 2 bar MAP sensor might also be causing some problems since this will shift all MAP and baro parameters.

 

Good news... I did some testing tonight and found RPM is linked to the timing increase, not MAP, or 2 bar MAP... verified using 1 and 2 bar sensor (also 53kpa or 100kpa BARO @ Key On have no affect on Timing).

I've read somewhere else timing is automatically increased as RPM increases.. now we have even more proof of that.

I simulated RPM using an old opti spinning with a grinder, simulated MAP using an air compressor, from 50kpa, 75, and 100kpa.

Held Throttle WOT (and disconnected my injector driver.. ha)

Loaded a file with 10 degrees of timing in all tables beyond 50kpa at all RPM. Set all temp offsets to 0, set all min timing to 1.

1) Ran 50kpa MAP (0 boost) from 400-6375rpm, showed the following:
400-700rpm = 10 degrees timing
800-2100rpm = 11 degrees timing
2200-3700rpm = 12 degrees timing
3700-5300rpm = 13 degrees timing
5300-6300rpm = 14 degrees timing

2) Ran 75kpa MAP (7.5psi) at same RPM's as above with same timing results:
400-700rpm = 10 degrees timing
800-2100rpm = 11 degrees timing
2200-3700rpm = 12 degrees timing
3700-5300rpm = 13 degrees timing
5300-6300rpm = 14 degrees timing

3) Ran 100kpa MAP (14psi) at same rpms as above with same timing results:
400-700rpm = 10 degrees timing
800-2100rpm = 11 degrees timing
2200-3700rpm = 12 degrees timing
3700-5300rpm = 13 degrees timing
5300-6300rpm = 14 degrees timing

4) I then ran "stock" 100kpa BARO Key On with 100kpa load... same results (so I wont post them).

-----------------------------------------------------------------------------------------------------------------------------
Edit - Added the following timing tests... All were tested with varying amounts of MAP pressure from 50-100kpa with no affect on timing...

---------------Setpoint-5 degrees--10 degrees----15 Degrees----20 Degrees
400-700rpm---=--------5----------10------------15------------20
800-2100rpm--=--------6----------11------------16------------21
2200-3700rpm-=--------7----------12------------17------------22
3700-5300rpm-=--------8----------13------------18------------23
5300-6300rpm-=--------9----------14------------19------------24
6300+rpm-----=--------10---------15------------20------------24-25

 

Thats awsome!! lol well atleast we know that we just have to enter 5 degrees less or so in our timing tables. Why cant the op get his timing to below 26

 

I dont know, I asked to see his datalogs and LT1 file and never got a response. There's probably other stuff affecting the timing but the MAP/BARO had absolutely no affect on it.

 

quick reference for me to get a base tune done. what kpa translates to atmosperic? what kpa translates to say 5 psi? 9 psi?

thank you

 

Are you asking for mine? I started with your tune actually that I got from Engineermike that he slightly modified then it was doing the 26 degree timing thing.

My laptop is too old to connect to the internet so I have to go through a work computer via a floppy disk to get the tune back to where I can email it. Do you want a copy of my tune/datalog?

 

Yea if you can email the file and the datalog somehow that would be good.

I was thinking it had something to do with the BARO being half of what is normal but when I start at normal KPA (100) the timing does the exact same thing.

Only other sensors/things that werent as they usually are on a running motor are coolant temp and closed loop, but I wouldnt think closed loop would affect timing and coolant temp shouldnt matter if the values in all the coolant temp boxes are the same (0).

codytherott
@
hotmail
.com

 

Update to an older post i made about the timing

Reason: My latest non-running timing simulation shows up to 4-5 degrees of additional timing based off of RPM and I didnt know why that didnt match the one running/driving datamaster log comparing 15 and 20 degrees requested timing since those logs started with lower timing but but ended up at redline with about the same results...

I just looked back at the file I used and saw I had the stock "minimum spark advance" tables which look like this:
15@4800, 17@5200, 18@5600, 19@6000+... so this explains the reason why 15 and 20 timing settings end up close in that post...

First run I set timing to 20 in ALL wot tables, and results (using 15-19 degrees in "Minimum Spark Advance" from 4000+rpm")
4400rpm at 23 degrees,
5200rpm at 24 degrees
6100rpm at 24 degrees where I have rev limit set.

Second run I set timing to 15 in ALL wot tables, and results (using 15-19 degrees in "Minimum Spark Advance" from 4000+rpm"):
4400-5000rpm at 18 degrees,
5000-5800rpm at 20-22 degrees
5700-5900 22-23 degrees where I have rev limit set.

 

Sent TC an email about the max of 5 degrees of additional timing linked to RPM and they didnt know why that happens but wanted a look at my file so I sent it today:

Hi Dan,

Hmm, strange. I can't think of anything that would add advance based on RPM like that but if you get a chance, send me the calibration (.bin) file you are working with so I can take a look at it.

Best regards,

TC

 

I posted a few links about that in reference to how the timing increases with RPM, there is one on the first page someone asking as well, thanks for the exact numbers though, on my old setup I had the timing at 28* at 7000rpm or so so that I would get about 33* in the end, even saved a word pad, thats cool how to simulated it with an opti spinning

 

yea I didnt remember who posted it but I could remember it being talked about here and other places as well.

Strange thing in my datamaster logs is the rpm maxes out at 6375 but it appears the PCM continues to calculate RPM since the injector duty cycle increases to climb. Is that normal?

The 15,000rpm angle grinder really gets the opti spinning! Even managed to blow the rotor apart in the beginning!