View Full Version : Idle Spark Advance?


Blown Interceptor
07-11-2006, 06:18 PM
Is this for tuning in park only? I know it says drive and park, but I have been getting some detonation around 1600-2000 rpm in any gear. Is my table too high?

Thanks,
Jason

Blown Interceptor
07-12-2006, 12:57 AM
Noone has any ideas?

ninobrn99
07-12-2006, 01:05 PM
try bringing it down 2* @ 1600 and 2k and/or adding a bit more fuel.

Blown Interceptor
07-12-2006, 01:12 PM
try bringing it down 2* @ 1600 and 2k and/or adding a bit more fuel.


I'll try lowering it...thanks Nino.

ninobrn99
07-12-2006, 01:20 PM
try adding fuel if that doesnt work. Also, do it to both spark tables, idle and high octane (also low octane if you're running in SD). Id do one at a time to see which is the culprit though. If you're still getting some detenation, then try the high octane table, then the low if in sd, then add more fuel. Someone chime in if Im wrong.

Nithros
07-12-2006, 06:27 PM
You may still get the knock if what the sensors are picking up is drivetrain noise. Any way you can up the octane to check this?

Blown Interceptor
07-12-2006, 06:36 PM
You may still get the knock if what the sensors are picking up is drivetrain noise. Any way you can up the octane to check this?


Not here is ca...I could get some race gas, but I don't want to spend that much for a couple of gallons. I lowered 2*(per Nino), it helped. Now I get some knock at lower RPM's. So, I guess I need to lower it 2* from 400-800.

ninobrn99
07-15-2006, 02:49 PM
Hey Jason, any update?

Blown Interceptor
07-16-2006, 12:22 AM
Hey Jason, any update?


I took out 2* starting at 1500 it seems fine, now I get some knock at 500. So, I am gonna take out 2* there, and see what happens. Thanks for suggestion Nino! Hey, are you in San Diego, or did you move? We need to have a send off cruise for you.

ninobrn99
07-16-2006, 01:03 AM
cool. glad i could help. Im still on deployment. Ill be there soon though ;) Im not moving till the beginning of next year and yes, we do have to have a cruise! :D

GuitsBoy
07-17-2006, 02:40 PM
Not here is ca...I could get some race gas, but I don't want to spend that much for a couple of gallons. I lowered 2*(per Nino), it helped. Now I get some knock at lower RPM's. So, I guess I need to lower it 2* from 400-800.

For future reference, you can go to home depot or lowes and get a gallon of paint thinner (xylene or toluene) and put that in your tank to raise octane about 3 points.

white2001s10
07-17-2006, 03:00 PM
Is this for tuning in park only? I know it says drive and park, but I have been getting some detonation around 1600-2000 rpm in any gear. Is my table too high?
Thanks,
Jason

base spark in drive is determined by vehicle speed. Speed has to be below a certain value before you are using that base spark table.
Once speed is above that value you are using the main spark table.

98Z28CobraKiller
07-17-2006, 03:07 PM
It's probably the crappy 98 knock sensors. I had to desensitize mine as I was picking up false knock all over the place. It's a known issue and I think that GM makes a fix that includes new knock sensors and a new harness for them.

SSpdDmon
07-17-2006, 03:16 PM
base spark in drive is determined by vehicle speed. Speed has to be below a certain value before you are using that base spark table.
Once speed is above that value you are using the main spark table.
Correct. I believe it's 4mph/10mph on the f-bodies. Once TP% exceeds ~1.2% or VSS exceeds 4mph or 10mph (depending on the OS), the car switches to the high/low octane tables. Remaining timing scenarios are determined by the base spark tables.

wait4me
07-17-2006, 03:34 PM
for reference, 2002 camaro,

It uses the base timing table in drive ANY TIME your foot is off the gas and tps % is less than 1.19.

The dissabling table for that via MPH is on table B5917. which from the factory is 255mph.

Trucks however have it not use all 4 tables all the time like on ours.

98Z28CobraKiller
07-17-2006, 07:41 PM
for reference, 2002 camaro,

It uses the base timing table in drive ANY TIME your foot is off the gas and tps % is less than 1.19.

The dissabling table for that via MPH is on table B5917. which from the factory is 255mph.

Trucks however have it not use all 4 tables all the time like on ours.

I will have to check this out. It does make sense. If not, why would the base spark table have so many cells for so many RPM's?

wait4me
07-17-2006, 09:52 PM
It is right, Im positive. :)

98Z28CobraKiller
07-18-2006, 08:19 AM
It is right, Im positive. :)

I sent you a PM about getting a new 98 PCM from you as the one that we have been shipping back and forth is still having the same problem for me. I kinda need one fast. If my core is worth anything to you, I will send it back to you.

Blown Interceptor
07-18-2006, 08:54 PM
For future reference, you can go to home depot or lowes and get a gallon of paint thinner (xylene or toluene) and put that in your tank to raise octane about 3 points.



I was just reading about doing that on the Corvetteforum...people said that does not work.


If it does work...can I do that on a regular basis, or is it a once in a while thing??? Is it one gallon per tank full?

Jason

GuitsBoy
07-18-2006, 09:05 PM
some forced induction guys swear by it. F1 race cars run on a reduculous percentage of toluene, like 85%. Premium gas already contains 15% - 20% toluene right out of the pump.

You may be confusing it with acetone additive to increase milage and slightly raise octane, but this has been proven not to work.

Blown Interceptor
07-18-2006, 09:08 PM
some forced induction guys swear by it. F1 race cars run on a reduculous percentage of toluene, like 85%. Premium gas already contains 15% - 20% toluene right out of the pump.

You may be confusing it with acetone additive to increase milage and slightly raise octane, but this has been proven not to work.



Here is what I was reffering too:

http://www.ls2.com/forums/showthread.php?s=&threadid=422848


It was actually LS2.

So, can I run all the time, one gallon per tank full?

GuitsBoy
07-18-2006, 09:13 PM
Yeah, they were calling BS on acetone increasing milage, which I agree with.

Toluene or Xylene are a different matter. Heres a good link that they referenced, and Ive seen posted a bunch of times before: http://www.gnttype.org/techarea/misc/octanebooster.html

And yes, you can run it all the time, but higher octane fuel does not increase performance by itself unless youre experienceing knock from too high compression or too much spark advance.