[Guest]

I've noticed under drag race conditions that engine timing while in WOT is only about 18 - 22 degrees.
That seems too low and costing HP.
At idle it's 17 and at highway speeds 41 degrees.

Have you monitored your timing while in WOT, and if so what was the timing at with no knock ?

What is the best way to bump the timing for WOT conditions?

Thanks,

 

[Bob57]

I guess it takes the snap on scanner for this, right? Or is there some other Cheaper way to do this?

 

[Guest]

Another PCM diag tool that runs on yout laptop P/C is called Autotap.

It allows you to drive while the diag tool records/collects what the PCM monitors/controls.

I highly suggest anyone with a C4 or C5 to learn how to monitor your E/PCM so you know exactly what the heck is going on within your engine functions

John

 

[Hib Halverson]

Don't take what you see on the scan tester as the total spark advance.

What scanner tells you is only the spark advance the PCM sets. It does not take into account the physical location of the crankshaft sensor and it's relationship to TDC.

You have to know that figure to be able to compute the total advance from the scan tester number.

For example. If the crank sensor is located 10 deg ahead of TDC and the scan tester shows 22 deg, you have 32 deg. total advance.

As to where the crank sensor is in relation to TDC in a LS1/6?

Good question that will take some research.

Rest assured, however, that the spark curve, regardless of what you see on the tester, is being maintained at the most aggressive value it can with the engine not in detonation. That's the advantage of ESC (electronic spark control) and a feedback loop using the knock sensor as input.

 

[N4C5S]

Nice one Hib......

I've been wondering about that stuff myself.....

JC

 

[BADASSZ06]

Do the LS1/LS6 have a mark on the balancers for TDC. If so couldnt you use this to figure the position of the crank sensor. I really think the Spark Knock system is great, but I bet Gm didnt put it on the edge because of varences in cars. Sometimes people take GMs word and theory a little far. In all reality ever car is different. Thanks for the info TeamZR1 I am looking to buy the diacom soon, mabey we can compare our notes to figure it all out.

Thanks

 

[Guest]

On 2001-08-01 13:24, BADASSZ06 spewed forth this drivel:
Do the LS1/LS6 have a mark on the balancers for TDC. If so couldnt you use this to figure the position of the crank sensor. I really think the Spark Knock system is great, but I bet Gm didnt put it on the edge because of varences in cars. Sometimes people take GMs word and theory a little far. In all reality ever car is different. Thanks for the info TeamZR1 I am looking to buy the diacom soon, mabey we can compare our notes to figure it all out.

Thanks

IMHO, think the knock sensors or their programming in PCM is a bit too sensitive esp when your running headers and a more radical cam.
A 2 resistor network on each sensor can cure that or have someone like Ron Zimmer tweak your PCM code to cure some of the knock issue.
I find though most of the knock is due to LSX running too lean and I can dial knock out pretty easy now.

BTW, Diacom is only for non OBD-II cars/trucks. For C5s you need like Autotap or any compliant OBD-II monitor diag tool.

John