Decel Fuel with AEM

[FattyBoomBatty]

I seem to only see the gauge read lean on decel at very low rpm (around 1500 and below), anything higher and it will go very rich on decel.

in the little box for decel fuel my settings are:
Fuel off above RPM: 2000 RPM
Fuel off below load: -12.06 PSIg
Fuel off below TPS: 1.95 %
Fuel off Coolant min: 30 degrees F

I may have just answered my own question when I saw the TPS was labeled in percentage and not voltage.

I did a quick check with the calculator and 1.95% is like .08775 volts (assuming 4.5 is the maximum which it is pretty close to that).

Can I raise that percentage up to say, 15%? Because I've watched on the computer with the car running, sometimes the closed throttle voltage will vary a bit, and go higher than .08 volts (like up to .45 volts once if I recall correctly (I may have done a TPS reset then)).

[Shane@DBPerformance]

You might need to raise the "Fuel off below load". You want the TPS % to a little over whatever it is with your foot off the gas. You usually need some amount of room for flaky readings or slight changes in voltage.

Let off the gas at 3000-4000 rpms and see how much vacuum the car pulls on decel. Set your "Fuel off below load" a bit above that. If it pulls 12 psi of vaccum then try 11.5 or something. You just don't want decel fuel cut happening when you are actually trying to cruise.

[FattyBoomBatty]

Makes perfect sense, thanks!

[FattyBoomBatty]

Finally got this done, and it's much better now. I didn't touch the TPS setting, just the load was good enough, I set it to -10.89, anything lower than that wouldn't trip the function until below 3 grand. It just doesn't pull a ton of vacuum. I also set the rpm limit to 1800 since I am usually still decelerating there. It could even go lower, but it seemed fine to me for the time being.

[FattyBoomBatty]

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?

[Shane@DBPerformance]

Check the air temp compensation table and try adjusting it versus the air temps you are seeing. With no air temp correction at all, it should run richer when it's hot and leaner when it's cold. If it is way over compensating(too much fuel) in the air temp table for colder temps then try lowering it down some at that temperature. Going from 14-15s to 12s though seems like way too much though for the kind of values you normally see in the air temp table. Make sure your air temp sensor or coolant temp sensor hasn't failed and inturn giving extremely cold readings to the AEM and making it run really rich.

[FattyBoomBatty]

Ok, I will do that. I wasn't able to find an air temp compensation table earlier today when I was looking, but I'll just search the PDF instructions. :)

nevermind, found it. Just being dumb.

[niterydr]

Ok, I will do that. I wasn't able to find an air temp compensation table earlier today when I was looking, but I'll just search the PDF instructions. :)

Fuel --> advanced fuel --> fuel trims.

[FattyBoomBatty]

Thanks! :)

[FattyBoomBatty]

Well, if the intake temps were low enough, it might have been adding fuel, but driving around town, it was acting fairly normal, so I don't know. I'll be observing and noting things over time. I did start messing with the Accel pump function because it was herky-jerky if I tipped in too much, and I had often seen a lean reading in the beginning, but had trained myself not to stomp the gas, but rather roll on the pedal.

So, I added more fuel, tried it out, same thing, added some more, and after a few repeats of this process, I decided it was getting worse, so I took out a bunch of fuel, and things started improving, and eventually I got it so I can romp on the thing off boost in any gear and it just goes, no missing or whatever, then the turbo comes on and things start making loud noises. It's great and the car actually feels faster because of it. I guess it's because I can give the turbo maximum load so it probably spools faster/sooner, or I'm just delusional.

Anyway, it's all working out, but I have another question in regards to the accel fueling. What is a good AFR to shoot for upon tip-in? right now it usually goes into the 10's then evens out in the mid 11's like it does on boost. Should I take a bit more out and make it so tip in only goes to low or mid 11's or is it better to have a good, rich squirt of gas? The reason I ask is because if less fuel made it run good, maybe even less will make it run great?