Need help with 383 TBI

[Hellbilly]

Went ahead and fired up, set initial timing, but having ignition issues. By recommendation, I used Accel distributor (performance replacement) and wires (superstock spiral core). Pertronix Flamethrower coil. Plugs are BKR5E. Anyone see this happen before? I tried putting the distributor from my old engine in it and it did the same thingScreenshot_20230130_065738.jpg

[1project2many]

This is usually because the definition file is reading the wrong values for spark or has the wrong math to convert the computer data to correct spark numbers. The way the numbers change appears to roughly match a spark table but the values are incorrect so I would suspect wrong math.

Which definition are you using?

[Hellbilly]

This is usually because the definition file is reading the wrong values for spark or has the wrong math to convert the computer data to correct spark numbers. The way the numbers change appears to roughly match a spark table but the values are incorrect so I would suspect wrong math.

Which definition are you using?

Advanced $0D TP5 v251

[1project2many]

There are notes that instruct the user to make a change to the conversion math. You can use those notes to make sure the math in your file is set up for zero degrees distributor angle.

There are two values that need to be set for your engine, Initial Advance and Injector Flow. Initial Advance: After loading A217 $0D TP5 v250.adx into your definitions menu, and opening, go to the Acquisition menu and open Edit Definition. Click on the + sign beside the word Values. An expanded menu will open. Drop down and click on Spark Advance. Then click on the Conversion tab at the bottom of the screen. Next click on the Set button at the top and change the last number in the equation to the Initial Spark Advance. This can be found at 4133 in the bin file. The Initial Spark Advance should match the advance set at the distributor. This will correct the Spark Advance display. If you decide to leave this as is, then you will need to add the appropriate amount of Spark Advance to the displayed amount when viewing, as the definition is set-up for 0 Initial Advance

[Hellbilly]

There are notes that instruct the user to make a change to the conversion math. You can use those notes to make sure the math in your file is set up for zero degrees distributor angle.

Thanks! I missed that, somehow, I'll check it out this evening

[Hellbilly]

I cant figure out the ignition issue... when it first starts up the advance is normal. As it starts to warm up and lower RPM, it starts flashing back and forth between normal and over 23000 degrees advance. By the time it gets up to normal temp, it never shows a normal advance. I've tried replacing distributor with the one out of my old engine and also the original coil. I've reburned chips, even tried the original calibration with nothing changed except engine constants. I checked for spark at each cylinder, and put fresh plugs in. I'm running out of ideas. When it shows a normal advance value, it runs pretty decent, but once the advance goes haywire, it starts missing and backfiring if you try to give it throttle to fast or Rpm go above 3000. Both the old, Known good parts and the brand new parts act the exact same way. I do have a knock sensor fault but I think it might be the wrong one... if you look it up on Summit, it shows like 3 different ones and doesn't say what the difference is. I can swap that out with my old one but I don't see a knock sensor causing this problem. I can try another temp sensor, but temps seem to be working correctly. No other data is going haywire like advance is so I'm at a loss with what would cause this. The PCM shouldn't even be able to calculate that range, right?

[Hellbilly]

These are the files I'm using
383 4.9 timing 79Fuel.adx

383 start up.BIN
Advanced [ATTACH=CONFIG]18867[/ATTACH]D TP5 v251.xdf
383 4.9 timing 79Fuel.adx

[Fast355]

I cant figure out the ignition issue... when it first starts up the advance is normal. As it starts to warm up and lower RPM, it starts flashing back and forth between normal and over 23000 degrees advance. By the time it gets up to normal temp, it never shows a normal advance. I've tried replacing distributor with the one out of my old engine and also the original coil. I've reburned chips, even tried the original calibration with nothing changed except engine constants. I checked for spark at each cylinder, and put fresh plugs in. I'm running out of ideas. When it shows a normal advance value, it runs pretty decent, but once the advance goes haywire, it starts missing and backfiring if you try to give it throttle to fast or Rpm go above 3000. Both the old, Known good parts and the brand new parts act the exact same way. I do have a knock sensor fault but I think it might be the wrong one... if you look it up on Summit, it shows like 3 different ones and doesn't say what the difference is. I can swap that out with my old one but I don't see a knock sensor causing this problem. I can try another temp sensor, but temps seem to be working correctly. No other data is going haywire like advance is so I'm at a loss with what would cause this. The PCM shouldn't even be able to calculate that range, right?

What you are seeing is the result of a bad mathematical equation in the scanner definition file. It is a known issue that has been floating around for a while. When you are seeing that 23000 value the commanded timing is actually negative. Nothing is wrong with the actual PCM, distributor or anything like that. A knock sensor fault can cause the PCM to command less timing. Most modified engines are going to run like poop if the timing is negative.