Jump to content
LegacyGT.com

Time to identify once and for all the source of my FKC


xt2005bonbon
 Share

Recommended Posts

  • Replies 130
  • Created
  • Last Reply

Top Posters In This Topic

Freezing temps are what I consider too cold for good gas mileage. With wind chill water would freeze, this means your transmission fluids are struggling to keep thin at this point too. Plus added air resistance, and if tires weren't pumped up reduced tire pressure, equaling to rolling resistance. If you had rain or snow, those hurt gas mileage too, since they increase drag and wheels will free spin loosing energy.

 

Back when I was more stock, I would get 24mpg when it was at freezing temps, going 70mph. I can see it being 20ish at best going 80mph.

05 LGT 16G 14psi 290whp/30mpg

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

Link to comment
Share on other sites

225/60/17 are almost 1" taller then 225/55/17 (stock), that's +3.4%, did you adjust the odometer mileage by that much before doing the mpg calculations? Basically when your odometer shows you traveled 100 miles you actually traveled 103.4miles When doing MPG calcs those extra 4 miles makes a big difference :).

05 LGT 16G 14psi 290whp/30mpg

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

Link to comment
Share on other sites

No I did not :hide:.

 

And I was just reading off the mpg gauge from the car. No actual precise computation of recording how many gallons, etc.... Yeah, shame on me.

 

Just checked tacomaworld tire calc and it looks when you think you're going 80 mph, you're actually going ~83 mph. oops.

 

How do you adjust the speedo btw?

 

In any case, already ordered a blackstone sample kit. We shall see. At least, she does not knock under high load and usually achieves boost target now (since I have adjusted the WGDC tables).

Link to comment
Share on other sites

No I did not :hide:.

 

Most people don't :lol:, this is why I stopped trusting peoples gas mileage claims. There are too many variables that most folks don't account for.

 

This really sucks because when trying to google for MPG related data, it becomes impossible to find anything meaningful. This is why I started doing testing myself :lol:

 

And I was just reading off the mpg gauge from the car. No actual precise computation of recording how many gallons, etc.... Yeah, shame on me.

 

Another tisk tisk. Gauge uses the MAF data for calculations, so it will never be as accurate as the real thing. But with that said, over a 1k miles, I've seen them be not too far off, but over 100-300miles it can be as much as 5mpg off.

 

 

Just checked tacomaworld tire calc and it looks when you think you're going 80 mph, you're actually going ~83 mph. oops.

 

How do you adjust the speedo btw?

 

You can't unfortunately. I wish there was a ECU setting. Also Odometer and speedometer are based on the same readings either. On my car 225/45/17 tires would have the speedometer be perfect, but odometer was off a by a little. For this reason I use GPS, and do all the math in my spreadsheet.

 

In any case, already ordered a blackstone sample kit. We shall see. At least, she does not knock under high load and usually achieves boost target now (since I have adjusted the WGDC tables).

 

I need to do the same, the kit is still sitting on my shelf :lol:

05 LGT 16G 14psi 290whp/30mpg

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

Link to comment
Share on other sites

In general though, I usually know my car is getting pretty good gas mileage by observing the gas gauge and seeing that I roughly do 100 mile per quarter tank (emphasis on 'roughly'). When I begin to see 60 miles or something per quarter tank, then I already know I am getting crappy gas mileage. And that's what I was seeing this past Saturday and I don't like it :mad:.
Link to comment
Share on other sites

  • 2 weeks later...

covertrussian, one question...

 

I started to notice yesterday that in part throttle (~17%), medium load, I noticed steady AFR of 15.2-16. I also noticed no correction applied. So that means I am in open-loop mode right?

Next question, should it run lean in that situation? I would guess no.

If it should not, and since it is running open-loop, does that mean this issue can be fixed in the tune?

Link to comment
Share on other sites

Correct your in open loop mode and that is very lean, your map is probably at 14.7 fuel map value but it's running leaner which also means your MAF scales are off.

 

You can log the status of open/closed loop by logging the field called "CL/OL Fueling* (status)". If it's at "8" it's closed loop, open loop is "10", finally cold start open loop is "7"

 

Also, Throttle position doesn't matter, ECU uses "Mass Airflow (g/s)", stock calls for open loop above 80 g/s. You can reduce it by modifying an experimental "AF #1 Learning Max Threshold".

05 LGT 16G 14psi 290whp/30mpg

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

Link to comment
Share on other sites

Thanks for the feeback.

 

Regarding the CL/OL switching, seeing the fuel correct go from X% to 0% would imply a switch from close to open loop no? In other words, wouldn't it be sufficient to log this parameter to see if you switch between CL/OL?

 

So, in order to fix this issue, which table(s) would you 'play' with?

 

side note: now, I am wondering if this is contributing to these low load knocks I've been plagued with for so long. Although each time I logged this lean condition, I was not able to catch a knock event at the same time..

Link to comment
Share on other sites

Fuel map is the one your going to mainly mess with. Figure out what your average mass airflow vs engine load/rpm is. Once you do, look at the fuel map value, if it's 14.7 then richen it up.

 

Your low load knock is most likely from running too much timing down low, fix that before you go on any other wild goose chases.

05 LGT 16G 14psi 290whp/30mpg

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

Link to comment
Share on other sites

Regarding the CL/OL switching, seeing the fuel correct go from X% to 0% would imply a switch from close to open loop no? In other words, wouldn't it be sufficient to log this parameter to see if you switch between CL/OL?

 

Practically yes, technically no. Theoretically it's possible that you have a load range that has a "perfectly" dialed in LTFT, so you might be in closed loop but still have 0% STFT. Very unlikely that you'd see a your STFT pegged at 0% besides when in closed-loop, but it's technically possible.

Link to comment
Share on other sites

^Yeah I thought about that. Although from my logging experience, if it was still in closed loop, you'd still see the AFR swing a little around the target value.

I am realizing this now, but looks like in open loop, the AFR does not swing IIRC my observations. Correct me if I am wrong.

Link to comment
Share on other sites

This is why I have multiple gauge profiles on RomRaider :). Dyno logs have less stuff then casual driving ones, and highway driving have their own set. I get 0% LTFT all the time, so it's not unusual, a better one to use is 0% correction (STFT), that is always moving during open loop. But with that said, I just looked at one of my logs and even though CL/OL status was 10 (open loop), longer term fuel trim was still applying. This is even with D learning disabled.

05 LGT 16G 14psi 290whp/30mpg

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

Link to comment
Share on other sites

Hang on, I was referring to the STFT parameter, not the LTFT. In my case (and albeit the limited logging I've done), I kept seeing the STFT being stuck at zero during open loop. I did not see it moving at all. So you do then?

 

I think it should be good enough to use, but keep in mind it is possible to have 0% correction too.

 

covert, you're not using the btssm yet? If not, you really should.

 

Nah, I use a laptop, I do too many logs and reflashes throughout the week (during mod testing) to bother with inferior screen sizes :lol:

05 LGT 16G 14psi 290whp/30mpg

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

Link to comment
Share on other sites

Come on man, you can make good use of a 7" screen tablet.

 

This was an old layout I had before. And just like romraider, you can hit the defrost button to log. You can see LV on the fly man. The only downside is you can't upload a ROM to your ECU. Other than that, I bet you would love it.

 

http://legacygt.com/forums/attachment.php?attachmentid=213955&d=1438707135

Link to comment
Share on other sites

The beauty of btssm is you hardly ever have to look at the screen while logging if you so choose, just log away... no bulky laptop or tablet, no risk of running out of battery while logging a 5 hour highway drive or 2 minutes worth of WOT pulls.

 

Or enable auto logging on WOT and Btssm will self start and stop the logs for you, as many as you want.

Link to comment
Share on other sites

I should add that I do have a tablet set up in the 05 but the 06 has not. So the above layout is actually used on my phone (nexus 4). It is a pretty small screen, considering today phone standards :rolleyes:. Nonetheless, I see everything just fine. I am using a magnet holder like this one placed on the cd slot.

 

http://i.imgur.com/pyeHlYo.jpg

Edited by xt2005bonbon
Link to comment
Share on other sites

After careful observations and 'live logging', I am now convinced that long term fuel trim D is turned off. The LTFT is always at 0 (been like that for a very long time) and now carefully saw that the STFT gets stuck at 0 as soon as I pass 32 or 35 or 40 g/s depending on the load. I did see that open loop is set when this happens.

 

I believe I can check that in the tune right?

 

In any case, why would you want to turn that cell off?

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share




×
×
  • Create New...

Important Information

Terms of Use