IAM at .5625, hot weather, bad gas?

[MasAyinde]

So I have been tweaking my tune to get it just right and last week it was great. IAM at 1, no learned knock in the tables but a few random medium load knock events. Today I checked my LV and my car is adding timing and the IAM is .5625. The weather is about 35 degrees hotter than when I tuned it, and I just filled up 3 days ago. It was since that fill up that the car felt like the performance had degraded a bit, but that was also when the weather got hot. I wasn't able to get a log just yet, but is it common for the IAM to drop that much if it gets bad gas or the weather gets hot?

[Spec B]

Hot weather should not effect IAM...but it happenes sometimes; depends on the tune. I would be worried about the medium load knock tho...I do not think anything other than low load (less than 1.25) knock is acceptable.

[black318i]

Someone here ran 87 and IAM went down to like .8xx. There is a table that adjusts timing based off of IAT, but I've never heard of anyone needing tweak it. You need to post some data to get real answers though.

[rtbrjason]

The car should be pulling some timing as intake temps rise. It is possible you just need it to pull a bit more rather than actually tweaking the timing table. This is assuming you did not have any medium load knock events when you tuned 35 degrees cooler. Agree with Spec B that anything over 1.2 or so should be fixed..

[ClimberDHexMods]

I haven't looked into the following idea much, but here goes: There is a dynamic advance or timing advance table that references the IAM/DAM multiplier. I use both Cobb and RomRaider, so I'm not going to try keep their different names for the same thing straight. This advance table is added onto your base timing table. What you COULD do is fill up on 87 octane, then tune your timing. Then compare your 87 timing map to your 93 timing map, and that would yield an optimized timing advance map. That way if you ever did fill up on 87 accidentally, or you bought some really sketchy gas, you would be covered in all the right places by the IAM feature, in all proper proportions. Would be a cool exercise in tuning timing. Many tuners just make the timing advance table an arbitrary but healthy number such as 5.98, above a certain load threshold when bad gas starts to produce knock.

[black318i]

Timing is pulled when IAT is about 100+ degrees, but it does not show up in LV.

[rtbrjason]

Timing is pulled when IAT is about 100+ degrees, but it does not show up in LV.

 

It's a 2D table. Mine is pulling about a degree by 80* or so and more as it gets hotter.

[ClimberDHexMods]

That table is fantastic if you have a TMIC, and it makes a hot-air intake very useful in terms of the ECU. If you have a FMIC then you can probably zero out or significantly reduce most of those upper values. Would have to go to death valley to tune that table for anything other than stoplights and bad traffic.

[black318i]

Here is what mine looks like.

[MasAyinde]

I see that yours is tuned for warmer weather than mine. Here are the values for mine:

 

-40: 3.16

-22: 3.16

-4: 3.16

14: 2.11

32: 1.05

50: 0

68: 0

86: -1.05

104: -2.11

122: -3.16

140: -3.87

158: -4.92

176: -5.98

194: -5.98

212: -5.98

230: -5.98

 

I'm guessing that in 97 degree weather and stop and go traffic, IAT is well over 100, which would mean I'm pulling 3 degrees of timing. Would driving like this for long enough cause the engine to change the IAM value instead of using the IAT compensation table? I flashed a new map to take care of the medium-load knock, got the IAM to 1, drove about 40 miles and it's still there at 1. Gas is the same as before.

[rtbrjason]

That looks mostly stock. You would be pulling 3 degrees while in stop and go and probably closer to 1.5 degrees while moving in 97* IAT. IMO that is probably about right and if you're getting some mid load knock you might be better off addressing it in the timing table first.

 

If you're positive that you didn't have any of the mid load knock around 70* though, you can try pulling a bit more (maybe .7*) from the values at 86* through 140*.

[black318i]

I'm pretty sure my IAT comp table is stock. I believe my rom ID is 522n

[bugblatterbeast]

That table is fantastic if you have a TMIC, and it makes a hot-air intake very useful in terms of the ECU. If you have a FMIC then you can probably zero out or significantly reduce most of those upper values. Would have to go to death valley to tune that table for anything other than stoplights and bad traffic.

 

You shouldn't zero that table. You will either knock like hell at some temps or have a tune which produces much less power than possible while cold.

 

I spent a bunch of time driving with thermocouples attached to both a FMIC and TMIC core and the intake to get a correlation between the IAT and IC core temps for both setups. Using that data I generated a correction for the timing vs IAT tables for my particular FMIC setup. The corrected table still needed tweaking at each temperature point. This step took the longest as I had to wait for weather conditions to right and re-optimize timing each time. I like to keep the car within 1 degree of the knock threshold at every temperature point.

[ClimberDHexMods]

Very aggressive. Would you be able to post your findings? (data/table values)