In boosted applications and with nitrous it is sometimes necessary to change the amount of timing. When you spray you have to retard timing. A permanent change in tune would make you slower when not spraying than you would be with full timing. If you wanted to up the boost for some reason and wanted to make sure it was safe, you could lower the timing raise the boost and start raising the timing back up until you see knock retard then lower it to the optimal point. It would come in handy in multiple places. In an NA car there is no reason to change timing. You put it at a certain spot in the tune and for the most part it won't need to be changed until other modifications are done.

This would come most in handy for nitrous/alcohol injection (both of which I had and needed the IAT selector) applications, but SC and turbo could benefit. They already sell ignition boxes for nitrous kits that retard timing. Don't know how they go about it, but I do know that if this could be done that it would be much easier and cheaper... if that table was found in the PCM.

 

IAT only affects A/F ratio in speed-density. Your 97 LT1 has an MAF, which accurately measures the mass air consumption of the engine. The PCM does not need IAT to calculated the mass air flow like it does in the 93 speed-density LT1.

I believe there is a small adjustment made, like adding 3* of timing, based on IAT. But that appears to be (if I understand the tuners correctly) a simple adjustment, based on a single temperature point. If IAT gets really high, it doesn't add the 3* of timing, as I understand it. But if you IAT actually gets that high, you do need to avoid the extra advance, so its logical protection for the engine. A more frequent problem would be the heat soak the the LT1 IAT seems to suffer from, because of its location, and some people appear to have avoided the high temp timing penalty by relocating the sensor to a point where is more accurately measures the incoming air temp.

Switching to Moderator hat..... there was no reason to call someone who expressed a valid opinion "clueless". Flaming is not acceptable.

 

It still seems strange to me. Everything you'd think would have the same program "setup" the gtps have MAFs as well. They react very similar with the stock tune doing he same thing as each other does meaning that they work off the same table as each ithe when stock... So why does everyone say the lt1 PCM doesnt have something that the GTP does have. I know you guys are VERY knowledgeable but have you personally looked through the pcms? Again, I just want to know cause it seems like a worthwhile mod to me and you guys seemed quick to discount its ability to even be done

 

I'll have to admit.... I never looked into the details of the GTP PCM. I have however, spoken face-to-face with the guy who wrote LT1_Edit... not sure what that's worth in your view. They ran a simulator to vary the inputs to the LT1 PCM, so they could measure the effects on the outputs.

If you're so sure its a good idea, try it and tell us how it works, rather than criticizing everyone who doesn't happen to think its the greatest idea since sliced bread....

 

The people that have developed different versions of LT1 tuning software have not given us ignorant people a table to manipulate. You would think they would have found this table by now.

 

I'm not criticizing you. Tell me its a bad idea, great! I dont really care. Everybody keeps saying it can't be done. Thats the idea of this thread. I was just trying to find out what you guys were basing this immediate "no" answer off of. I know you guys know your stuff but I dont know if you know tuning our specific PCM. clearly you do. Now I know. This thread can now die. I have my answer.

 

nope, I think I'll have the last word.....





I have a "Happy ****"

 

....... how uncalled for