GT350 CAI--"High" IATs causing timing/knock sensor activity?

[strengthrehab]

Weirdest thing.
I started having positive knock sensor activity (per ngauge) lately. I began doing some datalogs.

Generally, in the AM when IAT's are lower (about 8 degrees above ambient), I get max timing and neg knock numbers on the ngauge. WIthout changing anything except higher iat's, my timing drops about 3 degrees and get slight positive knock sensor activity.

Anyone have this issue? Higher IAT dropping timing?

Sponsored

 

[markmurfie]

In the stock tune there is a table that modifies your spark based on the IAT along with many other tables. Most tuners "0" this table out to gain more control over the timing and to know what it is doing. I am against doing this because it gives the ECU less control in varying environments. You also get what you are asking about. Some will "0" it, tune, then replace the table. This is the least a tuner can do. I would recommend taking two logs and sending it in to see if they can modify the tune to compensate for the IAT. You want your ECU to rely on the knock sensor as little as possible.

 

[strengthrehab]

I've sent in lots of logs. LiKe 10. I have a few different issues going on.

It is frustrating as I'mentioned in Houston. If my tune is going to pull this much timing, I may as well get rid of the car in the summer.

 

[markmurfie]

What its the actual total timing difference?

 

[strengthrehab]

Well today it was 5 degrees 28 vs 23. I was battling a fuel issue also but the above runs were same fuel, only difference was 15-20 degrees of ACT/IAT

 

[markmurfie]

Well stock every 10* above 100* IAT is minus 1* of spark timing at the WOT range. Every 10* below 100* IAT is 1/2* of added timing until 70* then it get even less.

If the 2* that were spouse to be removed were not the knock sensor could easily turn this into 5*. Knock sensors are safety nets. Relying on them will save your engine before allowing it to make power.

Now if your tune was dialed in at 70* IAT with 0 IAT modifier this could translate into 4.5*. Then the knock sensors would be responsible for the extra 1/2* and are doing a great job. Still prefer not to rely on them and just have a dialed in ECU.

Most people give up and switch back to an enclosed intake. They usually run cooler IATs.

 

[strengthrehab]

I'm going to go back to stock this afternoon and see how it goes with IAT's. I can barely get them below 20-25 above ambient while driving in town once the car heats up. Highway is about 7-10.

 

[Jn2]

Sounds like your IAT modifier tables need some adjusting...I'm in Austin, only a few hours away from you and have them set up to work pretty well for the heat we tend to get during hot summers...gimme a sec and ill post a pic, you are welcome to share it with your tuner to try on yours

Edit:

This set up works really good with our weather, yes it means you will run less timing in the middle of summer when even ambient is over 100f*, but during these times you weren't going to get full timing anyway.

 

[craigsix]

i noticed my fuel lines were not looking like they were running along the intake properly. but i never compared them to the stock gt im. i was thinking they might be running hotter than with the stock im routing.

Sponsored