I had my car tuned when it was around 50 degrees out on a dyno and afrs were set at approx. 11.2:1. Now when it's 80-90 degrees out my wideband is showing 10.2:1 roughly and when it's in the 70s it shows 10.5:1. I did a boost leak test and found no leaks. Car has bolts ons and stock turbo at 25 psi on pump gas. Is there something that needs to be changed in ecuflash to better compensate for weather changes? I logged the car and the intake air temp is reading correctly. The car was tuned at a well known dsm/evo shop but it just doesn't seem like there should be that much variation to me. Any ideas?

 

ROM, mods, logfile required to diagnose.

 

That's probably close to being right for safety sake. What are your air intake temp differences?

 

Hmm if it's close to being right maybe it's nothing to even worry about and I'm just too paranoid. I just assumed it would always be around 11.2 since that's the target afr. I'll have to do a couple of logs.

 

I had the same issues in tuning. The hotter the intake air temperature in the logs, the more fuel it adds which isn't bad unless you start getting knock from running to rich.

 

Yea I get why its doing it but I would have thought it would correct itself since it's always aiming for 11.2. I thought maybe there's a correction % vs air temp setting or something of that sort that just needed to be adjusted.

 

In a sense, it is correcting itself. Hotter ambient temps reduce engine cooling ability and hotter air intake temps are more prone to knock. So the ECU adds fuel to help cool the charge, reducing the chances of knock.

Im sure it can be adjusted. Just remember that you're taking some of the control away from the ECU.

You'll need to look at your data logs. My guess is if you tried running 11.2 AFR in 90F ambient temps, you could still end up at the same(or even less) power due to knock.
Of course I'm speculating here, but I tend to err on the side of caution.

 

The table you are looking for is in "global fuel" if using tephra and it is called fuel trim vs. air temp please be careful adjusting this table as others have mentioned the ECU uses fuel to compensate for increased temps, not timing... well to a degree, just be careful

George