8.1 Swap tune

[Bocephus79]

Had my pcm tuned mail order before I finished the swap. At this point it runs awesome in open loop. closed loop I'm seeing KR and it seems low on power. Anything over half throttle it falls on its face. Thanks in advance for taking a look

[jimbos'ss]

Is this Ed?

[Dr.Auto]

I'm working with a 8.1 right now. I have noticed there are a few spark multiplier tables you need to consider or zero out. Be sure to check those out. Also.... it doesn't seam to matter how much I tone down my spark table from stock. Its seams as though the knock sensor on this engine is extremely sensitive. I don't know if it's block design, sensor design or if there really is that much spark knock happening for real. I'm not sure... and there doesn't seam to be many people in the know out there playing with the 8.1 that have been able to say. I am curious also however because I am having the same problem. Not to mention a few other issues I have listed in a another thread a few spaces away from this one. People in the know please chime in.

[STR8BALLN]

Your High Octane spark advance table in your part throttle areas are higher than the max torque timing tables.

You are running alot of spark advance.

[Bocephus79]

thanks for checking it out. Like I said this was from a reputable tuner. Obviously it's a canned tune, before I had the software. Now time to keep the reading up and slowly figure itout

[STR8BALLN]

thanks for checking it out. Like I said this was from a reputable tuner. Obviously it's a canned tune, before I had the software. Now time to keep the reading up and slowly figure itout

There is a guy in another thread who has a 8.1 and look at his timing tables as well. Then find the stock 8.1 and you will get an idea of how high your spark advance is. Most mail order tunes I have seen are mild for safety, yours is definitely on the aggressive side.

[Bocephus79]

I'm working with a 8.1 right now. I have noticed there are a few spark multiplier tables you need to consider or zero out. Be sure to check those out. Also.... it doesn't seam to matter how much I tone down my spark table from stock. Its seams as though the knock sensor on this engine is extremely sensitive. I don't know if it's block design, sensor design or if there really is that much spark knock happening for real. I'm not sure... and there doesn't seam to be many people in the know out there playing with the 8.1 that have been able to say. I am curious also however because I am having the same problem. Not to mention a few other issues I have listed in a another thread a few spaces away from this one. People in the know please chime in.

Dr Auto, Went to friends and drove his 2003 bone stock 8.1. Logged tons of KR all over the place. He has over 150k on it and 100 of it is pulling a 9000lb camper. Starting to think you may be on to something about the sensitivity.

[Bocephus79]

There is a guy in another thread who has a 8.1 and look at his timing tables as well. Then find the stock 8.1 and you will get an idea of how high your spark advance is. Most mail order tunes I have seen are mild for safety, yours is definitely on the aggressive side.

Thanks! yeah did some comparing and tweaked some. Without a dyno it's hard to tell, And considering How I saw a ton of KR in the stock truck as well I think I may leave it very close to stock