Combinedft at WOT

[M4s73r]

So I have my combinedft at idle looking real good. Right between 0-2.1. After doing some WOT pulls I noticed my combinedft was at -3.9. What am I missing here? Shouldn't it be at 0.0%?

 

[Boostdriven]

You need to log both, combinedft and short term ft, stft. Your fuel trims are adjusted anything your car is in closed loop mode. So when your cruising they are being use/adjusted. Wot does not effect your fuel trims.
What you need to do is take your car out for a drive and and start a log while logging your combinedft, stft and closed loop. Drive your car for 5-10 minutes whole staying in close loop mode. Stop your log and right click on your screen anywhere, window will pop up, select MAFadjust from from combinedft. That will make suggested changes to your MAF calibration. It might be a little choppy so smooth it out a bit, save changes to the ecu. Now go to the top if your screen and click on ECU and reset your fuel trims. Repeat the process few times and you will c how your fuel trim will get better.

This will only make changes to your MAF calibration in closed loop mode, wot calibration you will have to do manually. If you get on ecmlink website there is a lot it useful info there as well. Hope this helps.

 

[M4s73r]

Been there and did all that. Stft is good. Maybe I need do do another maf adjust.

 

[Boostdriven]

Your fuel trims will fluctuate a little with temperature change. When your car is cold your combinedft will go negative but once it warms up and u drive the car a bit they should level out closer to 0. As long as they stay around +/-5 you should be ok.

 

[M4s73r]

And I'm seeing that at idle. It's just when I'm at wot do I get the -3.9. And it locks in and stays there.

 

[Wildside22]

So the issue is that your comninedft at idle is good but at wot it drops and stay at -3.9 during the pull?

 

[Boostdriven]

Yeah that should be fine as long as your car runs and drives good. When I made 580 whp, my tune was what most people would consider backwards

 

[M4s73r]

Yeah it's running ok. I'm just starting the tuning on it. Getting little .4, .7 blips of knock. Not sure of that's knock or phantom knock

 

[Boostdriven]

At what rpm/throttle/boost are you seeing knock

 

[M4s73r]

http://www.dsmtuners.com/forums/newbie-forum/457927-wot-pulls-need-help-advice-little-issues.html

Here's a log that shows it.

 

[dacowgod]

FuelTrims are not applied at WOT... combinedFT is only used for Idle/Cruise (i.e. Closed loop operation) .. WOT is open loop... so do not use CombinedFT when dialing in WOT.. use a logged Wideband value compared to target AF Ratio to tune at WOT... .

.4 and .7 and 1.1 is almost always noise... its usually not repeatable in any way or fashion.. I start paying attention to knock at around 2 degrees and higher..

 

[Boostdriven]

I can't look at your log cause I'm doing this off my phone. The knock you're seeing is not a big deal, .4-1.1 isn't much. It could be because you're running so rich. You need to get your air/fuel ratios to about 11.5 in boost.

There are few ways you can go about this. First you want to calibrate your MAF sensor and make sure in your log boostestimate matches your actual boost, I'm assuming you have a map sensor wired in to your ecu for logging purposes.

Depending on the boost you're planning to run, 3" GM MAF will start to be over ran at about 3000 htz. You mint have to use a MAF clamp option in your link. If you end up using that option set your cross over point to MAF clamp at about 2700 htz. The sliders in that window function similarly as your MAF adjust. You will have to adjust them accordingly to get your boostest to match your actual boost.

When you get those things close there are two ways you can adjust your fuel. You can either use fuel sliders on live access under fuel or in direct access under max octane. Since your car is running so rich I'm assuming you haven't messed with your fuel cells in you directory access under max octane. If you open that window your fuel map will probably be stock and in the upper rpm and load the cells will have numbers that are around 9.5 or maybe even in the mid 8s, you can change that whole fuel table and use it just to tune your air/fuel ratios, or you can just leave that alone and just use the fuel sliders in your live access under fuel. That's how I had my car turned when I made 580 whp. I don't have a way right now to post a picture if my fuel table but if I get next to a computer I'll do that. I run SD now so I use my VE table to do all the tuning, my fuel sliders are set to 0. My max octane table is set to where I would like my air/fuel to be. In higher rpms and load I have my cells set to 11.5 that way when I tune all I have to do is match my actual air/fuel ratios to my estimated air/fuel ratios which is displaying whatever I have in my max octane table at a given load and rpm.

If you do decided to use your max octane table to do you tuning, changing those values will change your air/fuel ratios so be careful how much you change them so you don't lean out. Your easiest option would be to use your fuel sliders in live access under fuel.

Hope this helps. Once you start playing with it you will see how things work and what does what. Let me know if you need anything else.