23037* Spark Advance???

[dave w]

BLM & SA updates:

[Fast355]

BLM & SA updates:

SA is looking much better overall.

Under 2,000 rpm still looks pretty lean in the upper KPA readings.

From what I remember the OP pulled the higher pressure spring out and put a stock spring back in giving him 13 psi.

I am tuning on a stock Vortec 350 with a performer rpm intake and cast iron exhaust manifolds that is running at 15 psi. I had to drop the injector flow constant to 50 lbs/hr even though the injectors calculate out to 68 lb/hr just to get enough fuel to the engine in the 1,600-2,000 rpm range. Not my prefered way of doing things. If the injectors were flowing enough fuel for WOT the flow rate constant could be programmed closer to actual rating. I would expect even a mild 350 Vortec to require about 22-26 psi with 350 injectors.

I had the VE table maxed out and was still seeing +20% fuel addition from the BLM and more still being called for from the Integrator value. I cut the injector flow rate in the PCM by 30%. The last log had fuel trims in the 105-118 range but I had 115 readings where the VE table had previously been maxed out.

Problem is just judging by the duty cycle at 3,000 rpm the injectors will be static before 4,000 rpm.

[dhworkin]

It is a glitch when the timing drops below 0 degrees. But what is causing the timing to drop into the negative? I can load a bin file without the WBO2 perameter changes , and there is no negative SA. I take the same bin file and make the WBO2 changes and the timing goes negative and it’s popping out the throttle body. I believe Jimmie, Mitch and myself are having the same problem.

[donf]

It is a glitch when the timing drops below 0 degrees. But what is causing the timing to drop into the negative? I can load a bin file without the WBO2 perameter changes , and there is no negative SA. I take the same bin file and make the WBO2 changes and the timing goes negative and it’s popping out the throttle body. I believe Jimmie, Mitch and myself are having the same problem.

It's a glitch in Tuner pro nothing else. You are confusing data logging errors with something else. I spent a long time figuring this out in my van thread. The same untouched bin using an OTC scan tool instead of Tuner Pro will log a negative number but not the crazy number. It would be physically impossible to retard the timing 26000 degrees. Remember GM never released its source code to the public. All this has been reverse engineered for free. There are mistakes. I do not doubt you have a popping problem, but you are looking at a distraction, not the cause. You seem to have isolated it in your case. Something is wrong with your wideband o2. Either in the bin or the way you have it hooked up. I would start by removing the wide band O2 completely and re attaching direct to the battery to eliminate any feedback problems you may be introducing with faulty connections or the way you chose to install. A lot of us have used the Wideband feature in tuner pro with good results. Since you are having major problems look there first.

[dave w]

I've been curious to understand why adjusting Altitude Spark Bias to ZERO will stop the negative numbers? Possibly source code that has not been reversed engineered?

dave w

[donf]

I've been curious to understand why adjusting Altitude Spark Bias to ZERO will stop the negative numbers? Possibly source code that has not been reversed engineered?

dave w

Because doing that just bumps the actual timing everywhere by the 9.8 degrees. What I did to figure all this out is set the whole table to a fixed number in tuner pro then measure actual timing with a timing light, while changing different stuff.