dsmlink fuel trims

[droppinbottom]

Am I correct when I assume that a minus % on LTFT lo/hi means lean and a positive % would mean I am rich?

Just trying to get my initial settings correct (golbal and dead time) which are currently both at a minus %.

dan

 

[illeffekt vr-4]

negative is rich, positive is lean.

 

[Coup D E'Tat]

I get mine to +/- 5%, just as a reference I guess.

 

[olmytsi]

Trims show you what the ecu is doing to maintain the targeted a/f ratio. So when you see -7%, the ecu had to take -7% of fuel out to maintain the targeted a/f ratio (you are rich) and vice versa.

 

[droppinbottom]

I was told that since both of my LTFT trims are -4.7%(LO/HI), that those values are maxed out according to link and they may be farther off than that. My question is if that is true than why is everybody telling me to get the trims to +/-5% when -4.7% is a maxed out value?

Thanks

 

[GVR4592]

http://www.dsmlink.com/forums/search.php?

 

[droppinbottom]

WTF

As we all know the search button doesnt always get the results you want. I have been using the search feature over there ever since I got link and I am still a dumb ass.

Either way thanks, I will keep looking for my answers and hopefully get the car running like it is supposed to.

 

[GVR4592]

I went to the dsmlink forums and typed " fuel trims 4.7" into the search and came up with this thread: http://www.dsmlink.com/forums/showthread.php?t=7076&highlight=fuel+trims+4.7

It answers your question about the fuel trims being maxed out.

 

[MY1GDSM]

I know This is A Very old thread but... I stumbled along on in and
I wanted to clarify something about the fuel trims since not Everyone can Access the link Provided. like myself since I don't had Dsm/ECMlink

The Fuel Trims For a 1G Work like this(for anyone that does'nt know)

The most the trims can lean out is 4.7% or 18.8%of the trim
The Most the trims can richen is 9.75% or 39% of the trim

When someone states +/- 5% there talking % of the trims not of fuel since 1% of the fuel trims is .25% Fuel

So take a fuel trim of 100,122 and 93.4

100 Pretty easy the ECU is not adding or taking any fuel away
122 - 100 = 22 / 4 = 5.5% So the ECU is adding 5.5% of fuel in that trim
100 - 93.4= 6.6/ 4 = 1.65% So the Ecu is Removing 1.65% of fuel

 

[twdorris]

When someone states +/- 5% there talking % of the trims not of fuel since 1% of the fuel trims is .25% Fuel

That's only true if you're displaying trims in something like MMCD which, IMO, doesn't display them properly. The trims in DSMLink/ECMLink are displayed as percent fuel adjustments. That is, a +5% trim means a +5% adjustment to fuel in ECMLink. So when someone says they try to keep trims in the +/- 5% range with ECMLink, they're talking about +/- 5% fuel (since trim % = fuel % in ECMLink). Plus, if someone says +/- 5%, they're probably talking ECMLink numbers anyway because I don't believe MMCD displays negative adjustments. MMCD, I believe, displays trims centered at 100%. So a "-5%" trim would actually be displayed as 95% and someone talking in MMCD units would probably say they keep trims in the 95-105% range. But I've never actually used MMCD, so I can't be sure of that.

EDIT: Actually, since MMCD shows trims as real fuel % times 4, then someone talking in MMCD units would actually probably say they keep trims in the 80-120% range because a 95-105% range is pretty darn tight IMO.

Thomas Dorris
ECMTuning, Inc.

 

[bling5tatus]

That sure is a lot of "fumbling around in the dark" about an open source app. Anyone can look at the math that makes mmcd display fuel trims. How does dsmlink's math differ from mmcd's in a way that would make mmcd's inaccurate in comparison?

 

[twdorris]

How does dsmlink's math differ from mmcd's in a way that would make mmcd's inaccurate in comparison?

I just explained the difference in "math" above... ECMLink is displaying a fuel trim number that represents the actual fuel adjustment where as MMCD, I believe, displays 4 times that.

And I never said it was inaccurate. I just said MMCD wasn't displaying it "properly", IMO. It's using numbers much like the numbers TMO used to display back before (I presume) Todd had a full understanding of how the trims were being applied.

It's similar, IMO, to how TMO used to displaying knock "counts"...he didn't have an understanding of how a knock "count" applied to real timing adjustments at the time, so he logged them as "counts". I think he came around to understanding it all at some point, but never actually logged knock as an ignition retard value.

Logging fuel trims as number directly related to fuel adjustment amount and logging knock retard as a number directly related to ignition timing is simply more useful, IMO. Everyone is welcome to their own, of course.

Thomas Dorris

 

[bling5tatus]

Somehow that doesn't answer my question. What is your algorithm vs. MMCD's algorithm for calculating fuel trim? The people that are good at figuring things out can just see the difference for themselves. I'm not saying you dodged the question completely, I do however, IMO, "believe" that you beat around the bush to avoid giving a straight answer. If MMCD is an inferior logger and you're in the business of selling a product that surpasses the inferior functionality of the free software... please prove to us that it is better so those of us that haven't spent money on your system can justify doing so.

If your method is better, please show us in plain view how it is better. I await your relevant reply (Don't Obama the question this time Tom).

 

[MY1GDSM]

EDIT: Actually, since MMCD shows trims as real fuel % times 4, then someone talking in MMCD units would actually probably say they keep trims in the 80-120% range because a 95-105% range is pretty darn tight IMO.

Well. ... they wouldn't because 80% Is out of the range 81.2 would be the lowest...
please explain why IYO it would be hard to get the the trims within +/- 2.5% Of the target ...
BTW my trims are right now...107, 96.2, 103 and say around there as long as I'm the only person drivin the talon..

 

[twdorris]

Well. ... they wouldn't because 80% Is out of the range 81.2 would be the lowest...

. Yes, that's technically correct. My point was that to convert what someone would call -5/+5% in DSMLink terms to MMCD terms, it would be 80/120%. But, yes, just as -5% is out of range for a stock 1G ECU when talking in terms of DSMLink numbers, so too is 80% out of range when talking in terms of MMCD numbers.

I feel like we're getting drug down in semantics here. The ONLY thing I'm trying to point out is that MMCD displays values that are 4 times the actual fuel adjustment. DSMLink displays actual fuel adjustment numbers. It's not complicated math to convert between the two, of course. I'm simply pointing out the difference as there was some confusion above on this point.

FWIW, ECMLink extends the 1G fuel trim range to match that of the 2G ECU. That's a more useful range, IMO. Limiting negative adjustments to -4.7% is just too tight on many cars.

please explain why IYO it would be hard to get the the trims within +/- 2.5% Of the target ...

What I said is that it would be hard to keep it in the 95/105 range using MMCD numbers. That's within +/- 1.25%, not +/- 2.5%. Given how many different cars there are out there with different setups and varying levels of attention to detail, running within 1.25% of target at all load levels under all conditions would not be a practical general rule IMO.

Heck, even my bone stock (including the air filter!) EVO8 runs in the +/- 7% range. And I've touched exactly nothing on that car. The trims are expected to vary. That's why they're there. Trying to get our typical user to target such a small window would drive them insane. Some have a hard time getting the car to live in the +/- 5% range, much less +/- 1.25%.

So, yeah, IMO it would be hard to expect people to run in the 95/105 range using MMCD numbers. That's just too tight for a generalized target. Some cars with proper attention to detail, sure. But speaking to a general audience, no.

BTW my trims are right now...107, 96.2, 103 and say around there as long as I'm the only person drivin the talon..

Not bad at all. The trims on my 2G running an 85mm GM MAF were in the 0.8% and -1.4% range (103.2 - 94.4 MMCD numbers) yesterday when I took it out for a test drive. But I feel you and I probably keep our cars dialed in a good bit tighter than the typical user.

Thomas Dorris

 

[twdorris]

I await your relevant reply (Don't Obama the question this time Tom).

You seem to have a bone to pick and I don't care to play the game. I've already answered your question above. One is fuel trim adjustment and one is 4 times that. That's the math. There's nothing else to it. IMO, it's more proper to display fuel trim adjustments in straight fuel adjustment %. MMCD displays as 4 times that. There's really nothing else I can say there. There is no other math involved. I simply consider displaying 4 times the adjustment to be "improper". I didn't say it was inaccurate and I didn't say it was inferior. You're totally putting words in my mouth to try to create an argument where there is none. Please stop and please leave me alone.

Thomas Dorris