This is on a OBDII LT1 car.
Had the PCM dyno tuned with a LPE 211/219 cam a few years ago and recently went with a larger cam. I know I need tuning but the problem is I just autotapped this car a few weeks ago and I was seeing mostly -30 to -40* of timing being pulled.
02's are reading over 1000mv as well. Long term fuel trim is over 15% so yeah.. the car is running PIG rich.

My question is, does the crank trigger sensor serve more purpose than to read misfires? The crank trigger harness was damaged and a new pig tail was installed yet I'm not sure if the individual who connected it fastened all wires in their proper place.

Car runs good. Just real rich.

If anyone wants to see the file, let me know.

 

In looking at this file further it looks as though timing values are correct but showing a negative number.

 

It is just the way the tool you are using displays the timimg advance. Some tools show the - and some don't.
If you think about it, timing advance is rightfully going to be a negative number because it is BTDC. Your engine would barely or not run with 40º of timing pulled.

 

I appreciate the reply. I know all of about nothing when it comes to tuning or using autotap. The one that was on my car belongs to a LS1 owner. Not sure if there is a difference between LT1/LS1 autotap or if the difference is between OBDI and II.

 

Autotap will be the same for LT1 or LS1, but depending on the version you run I believe, it will display the timing as negative values.

Mine does for my car.

 

Hey Brian..... what's up?

You might want to read this. .

From the section on spark timing:

The crank position sensor is only used for misfire detection.

 

Thanks!

Hey Fred,

That's good to hear. Kinda freaked me out for a bit especially since it displays positive numbers for my friend's LS1.
Thanks for the reply and I'll be paying more attention to your webpage on autotap values here shortly.