I am just begining to tune my UTEC and I notice that driving around town at moderate RPM's my AFR's are like 13-14. I am talking cruising like 35-45mph at 3-4k rpms. The dashboard says I am at 0 load (that doesn't make sense to me either but ok).

So how do I make those afr's drop down? I have open loop fueling on and I thought this is the range where it kicks in.

Also some other observations... when I open up my logs in that nifty graphical logger program (can't remember the name off the top of my head) I never reach 100 % load. Also sometimes my injectors are near 94% duty cycle at WOT. Now I didn't think that I would be anywhere close to that range. I am not even running nitrous or alky ...YET.

I am running a larger walbro fuel pump. Would that be enough to throw off the afrs that much at OLF mode?

 

It would help to see some logs. That way we can give you a little better advise

 

0% load site will usually result in closed loop operation, your AFR's should be around 14.7:1 (more or less, 13-14 is normal) in low load cruising..

 

I would agree. My AEM ems is programmed with its wideband to cruise in the 13's. If you are at high boost, higher rpm, then I would worry.

It helped me a lot to have a dyno complete with the log at all rpm levels. Im still learning about a lot of this, but this made everything much more simple.

 

Im not convinced that the UTEC reports the Duty Cycle on the injectors properly. At 21psi with a TBE the UTEC would show me at 98% DC, which is just not possible. Especially since my AFR's were all fine. I really think it mis-reports that. Any tuner that has done a lot of work on hundred, if not thousands, of Evo's will tell you that your stock injectors are fine until you get a bigger turbo. Even then, you only need 660's.

 

believe it, I have tons of logs with evos at 97-99% DC.

Unless you are taking out a bunch of fuel up top , your DC will be very high there. The evo runs rich up top without a tune, once you tune it, your DC's will drop.

 

This was with a tune of 11.2:1 AFR's. I hooked up a different scanner to the ECU and it only reported the DC to be 64%, while the UTEC reported 98%. Just to be safe, I installed 800cc injectors, then I found that, even with scaling, the UTEC reported I was at 78% DC. Just not possible. Its reporting the information incorrectly, or I have some setting set improperly in the UTEC.

 

Closed loop? I think I may have my terms mixed up again. Anyhoo, I was trying for a more fuel efficiency but If I can't get the afr below 13 I don't see how I can build a map for that.

 

Closed loop adjustment is kind of a pain. You have to modify the 0% load column, and more importantly, you need something to look at your long and short term fuel trims. Any standard OBD-II scanner will do. Basically, you can add / remove fuel from the 0% column for your RPM range to try and help the LT and ST fuel trims get closer to 0. The issue here is the ECU will always shoot for 14.7:1 using the front O2 sensor. So no matter how much fuel you add or remove, teh stock ecu will always shoot for this value in closed loop. The only indication you have that you are making any changes is with the LTFT's and STFT;s.

 

13-14 afr at 0% load is typically what I see cruising around town. The utec leaves the control to the ECU when OLF isn't engaged. You can set when OLF takes over (I have mine set at 20%).

When I had the older software version on my Utec, I was showing a peak of 98% injector duty using the UCC. After I upgraded to 1.7 and turned on OLF, for some reason my IDC is around 75% at the same boost and close to the same AFR's.

 

And what scanner did you use?

 

Yeah, I tried taking away fuel in the 0% column but I still seem to hang around the 13-14 afr...Not having the ability to tune the crusing afr seems kinda silly. I understand the need for keeping afr rich and under ECU control at idle for problems like tipin and starting. But for crusing...this seems like a waste of expensive Chevron premium gas but what do I know...

 

"I was trying for a more fuel efficiency but If I can't get the afr below 13 I don't see how I can build a map for that"

To be more fuel efficient than a 13 AFR, you would want it HIGHER, not lower. Hhigher AFR means more AIR, less FUEL. Less fuel means better mileage.

 

doh..yeah..thats what I meant....man I wish I hadn't smoked all that weed when I was a kid.

 

I don't use a Utec, but I feel inclined to answer since adjusting fuel no matter if it's an AFC or another computer it's pretty relative.


This is normal, cruising AFR's should be around 14.7 but it will fluctuate a lot.

You don't want to make the AFR's go down, unless you like getting really crappy gas mileage.

I'm not sure why you don't see 100% load, like I said, I don't tune with UTec but I assume that you're referring to 100% throttle position voltage. 94% duty cycle is VERY believable depending on what kind of gas you're running and what amount of boost you are running.

That being said, ALKY should REDUCE not INCREASE your duty cycle because it acts sort of as a fuel. The only reason the duty cycle would increase would be because of increased boost.

It sounds to me like you need to read up a lot before going any further. The knowledge that you gain from doing that will save you time, energy and cash in the long run.


Posting logs always helps when you make a post like this as well, because even though you've described your issue, there might be something there in the logs that someone will see that you haven't seen.

Hope this helps.