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FattyBoomBatty · 06-09-2009

Last week I discovered I had a vacuum leak coming from the #4 injector o-ring in the manifold. SO, I fixed that and it changed the vacuum a bit and also the fueling stuff on the AEM. I went back into the decel box and dropped the threshold to like -9.8 psi and it has been working perfectly ever since.

But my cruising afr's were way more rich all of a sudden, I figured it's because it's not getting as much air as before under vacuum conditions. So on the way back from Branson yesterday, I whipped out the laptop and did some tuning for low load cruising, and got the AFR's back up to where they should be, in the high 14's and once in a while I'd see 15, but only for a second. I managed 26mpg and 452 miles on that tank, the first bit was in some hilly terrain before leaning it out.

Then after that it started getting cold in IA, and the AFR's went rich, kindof back to wherethey were before, mid 13's sometimes high 12s cruising, it was kindof pissing me off, but I figured it had to do with air temps.

Am I right to assume that? Conversely, when it warms up again, will it go back to being leaner? or am I going to have to tune for different air temps every time a cold front passes through?

06-09-2009	#5
FattyBoomBatty Banned Join Date: Dec 2003 Location: Boulder, CO Drives: Conquest Posts: 5,049	Re: Decel Fuel with AEM Last week I discovered I had a vacuum leak coming from the #4 injector o-ring in the manifold. SO, I fixed that and it changed the vacuum a bit and also the fueling stuff on the AEM. I went back into the decel box and dropped the threshold to like -9.8 psi and it has been working perfectly ever since. But my cruising afr's were way more rich all of a sudden, I figured it's because it's not getting as much air as before under vacuum conditions. So on the way back from Branson yesterday, I whipped out the laptop and did some tuning for low load cruising, and got the AFR's back up to where they should be, in the high 14's and once in a while I'd see 15, but only for a second. I managed 26mpg and 452 miles on that tank, the first bit was in some hilly terrain before leaning it out. Then after that it started getting cold in IA, and the AFR's went rich, kindof back to wherethey were before, mid 13's sometimes high 12s cruising, it was kindof pissing me off, but I figured it had to do with air temps. Am I right to assume that? Conversely, when it warms up again, will it go back to being leaner? or am I going to have to tune for different air temps every time a cold front passes through?