Running Lean

[snamtrac]

Ok, I was making some runs yesterday on a local road. My setup is as follows:

Big 16g ported, 550cc injectors, 2.5" exhaust, safc II, AEM wideband, ported 1g manifold, ported o2 housing, brand new plugs and wires, and I think the last time I checked the fuel pressure was around 34psi, running 19lbs of boost.

So I was driving along and while in 4th and WOT from like 3500-5000 it was 11.5-11.8 A/F ratio, but after that it started to climb. Now my settings two days ago were all -16% and it was 11.5-11.8 A/F ratio all the way to 7000rpm, but today at 5000 it started leaning into 13's so I richened it up to like -11% and it was 11.5-11.8 A/F ratio then at 6000 it would shoot up to the 14's. I richened it up again to -8% and it was still when making runs in the 13's (A/F ratio). It was wierd because this has never happened before. I would put it to -16% all the way up to 7000 and it would be fine, but yesterday it started to sorta buck at 6000. I cant think of anything.

Thanks for the help,

Kyle

 

[5150DSM]

Just an idea but...
Has the weather changed much during the past few days, like say a 10 or more degree temperature change?

 

[snamtrac]

Ya it did, but I didn't think it would make that BIG of a difference.

 

[Tevenor]

It does.

 

[ITSME4G63]

Ya since the weather changed, my shit is spitting black liek no other.

 

[1LE]

Yeah, weather is a huge factor it seems. The colder it gets, the leaner my car goes. I hate messing around with the settings all the time, so I just do my tuning when it's in the 40 degree range. I run rich when it's hot, but not too awful. If it's below freezing I don't have enough traction to go WOT so that's not a problem

 

[Tevenor]

Air mass per volume increases as temperature decreases and density increases.

 

[CanadianTSi]

Put your FP at 37psi where it should be.