So I switched to Open Loop fueling today and spent a couple of hours getting the AFR's in the right spot. One thing I noticed right away is that the car is real sluggish at partial throttle due to really rich conditions. Hard to find all those spots.. Anyway, was also surprised to find that my idle and cruise trims are running 14.3 instead of the standard 14.8 but I could not find a way to adjust the 0% load columns. Is this even possible? I will be putting cams in soon so I want to ensure that I will be able to adjust the fueling at 0% properly. Looking in the parameters section for open loop fueling it looks like the soonest you can start applying map changes is at 20% throttle.

 

You can alter the base setting in two ways, use the 0% column, or use the scaling feature (original) and set it slightly higher or lower until your basic trims are closer to what you want (Mine are almost at 0)

Remember, the 0% load site uses MAF offset until you cross into another load site.. and If I recall, over 4500rpm in the 0% load site also crosses into open loop.

Here's the trick (and it applies to all cars, but more so with guys with flashes already on the car)

Watch the injector duty cycle and timing from when you cross over from 0% load site, to the 10% load site.. If there's a large jump in either, you'll feel a hiccup..

Now.. The sluggishness you feel is a combination of timing and boost, you can bump the timing within reason, but if you look at your boost map, its probably very low in the 10-30% load site, I have it set alot higher so boost sets on very quickly, unfortunately this can result in a boost spike under certain circumstances. (and sometimes results in a CEL when the ECU thinks its an overboost condition that it can't remedy by disabling the solenoid)

Hope this helps a little.. on my blowthrough setup, I get the hiccup and other anomolous things pretty fequently as the MAF curve is very linear compared to the stock drawthrough, so it takes time to match the output so the timing is and fueling are where it should beon the te transition.

 

So I have tried changing values in the 0% load column and it does nothing. I added 10 points of fuel through the whole column and nadda. There has to be another setting that requires adjustment for this to work.
The closest I could find is in the Open Loop Fueling parameters. But the lowest you can set the value of Open Loop Mapping is 20% throttle position. Since the odds of you even being 20% during cruise is low this doesnt help. So, this definitely throws out any idle adjustments in the 0% load column with no throttle position. Ill give TurboXS a call today and see what I can find out.

 

Okay.. here's the problem.. at idle the car runs closed loop, no matter what you do, it will always try to run at 14.7:1 When I make idle adjustments, I base them on the fuel trims (long term and short term) Which means you need to be connected to both an OBD-II scanner to watch the trims, and the UTEC.. when you do this, you have to make your adjustment, then sit there and watch the short term fuel trims adjust accordingly.. after a few minutes you'll see the long term trims start moving.. the key is to make adjustments and watch as the car is idling until your LTFT's (Long term fuel trims) are as close to 0 as possible (typically -11% works best since it will allow the car to crank rich and start easier) If your idle MAF reading is 30hz, the output MAF reading at 950rpm should read around 38-42hz.. If your idle drops below that, and its like 24hz at 500rpm, bump that cell higher so it reads higer, around 34hz or so.. so what will happen is you will put around 1500rpm 0%, 1250 around +10%, 1000rpm +20%, 750rpm +35% and 500rpm +40% (Give or take) Don't use these values as gospel, since injector size and an aftermarket pump will affect this (the pump will affect it slightly) so watch your fuel trims.. once you get +/- 10% within the "Happy range" that the ECU likes, you'll find your idle quality is much better and it won't hunt and reset the trims every few minutes.. don't forget to run the car wtih the AC on Max for 15 minutes after you do everything to get the secondary accessory trims set too.. but if you get close, it'll go lean for a bit, and fairly quickly get back to stoich..

 

BTW, 14.3 may be normal for your car.. the fuel pump and even the calibration/location of your wideband may be why its reading 14.3.. as long as the car isn't hunting and nearly stalling, you should be ok.. Cams will also cause the car to run a bit richer overall since engine vacuum is a bit lower, but cams also wreak havoc with the idle MAF readings, since as the MAF value gets lower and lower, the karmann "Street" (the aerodynamic generation of the vortices that are counted breaks down and becomes unstable)

 

Trying to understand what you are saying here. So, I adjust the 0% load column and watch my fuel trims using the OBD-II scanner. Is that right?

 

Yes, watch the trims with an OBD-II scanner.. Take your time because the trims lag a few minutes behind.. the short term trims will show you that your going in the right direction, then you watch the long term trims as they adjust over time.. once you hit it, the trims will stay pretty stable at the percentage you want, try to hit within +/- 10% and you'll get a car that runs really well.. then button it up, shut the car off.. Wait about an hour, then start the car up, make sure the car starts easy, and idles when cold at a decent AFR... watch the trims again and you should be real close to where you want to be.

 

I think my real issue may be the fact that I am running an O2 simulator so the stock ECU isnt getting real data from the narrow band O2 sensor. I am assuming that the ECU uses this data to determine fuel trims and since the data its getting is false there is no way it could properly make adjustments. I am going to install a switch for the O2 sensor and turn it off to get fuel trims setup properly. Thanks for the info Jack!

 

Just so you know, O2 simulator has no impact on the fuel trims, the front O2 sensor is the only sensor used for the ECU's fuel control, the rear O2 sensor is only an emission related device, its used to determine the efficiency and light-off of the catalytic converter.

IF you had the simulator on the front O2 sensor, you'd basically never have real closed loop fuel control and it would likely run pretty poorly all the time. (Hesitation, stumbling, stalling, idle surging, cruise surging, etc..)