I last reset my ESL in january, 95 % of the fuel trim cells varied from 99 to 106 across the board.

Move on a few mths, i had to reset the battery and upon checking fuel trims they are all way down in the early 90`s and one was 89 !

Now, not sure if the fuel trims are actually worth worrying about ?

could it be the warmer weather now means it wants less fuel than when i last tweaked the map in the winter ? and if so does this mean once the fuel trims are set it doesnt adjust ? as before i reset the battery all fuel trims were healthy lol

cheers

 

Have you only just reset them? It can take a while for them to settle where they want to be.

I'm currently working on calibrating the MAF scale on mine to bring my fuel trims in line with where they should be so I'll be watching this thread with interest. I've come up with a spreadsheet and method for logging, then adjusting that seems to be working pretty well. Once I'm convinced it's doing what it should be, I'll post it on here with some instructions for anyone else that wants to easily calibrate their MAF with ESL.

 

Yeah , recently reset but every other time ( during winter ) the trims have always been above 100 , now they are in the low 90s with no change to engine setup

The car drives ok but it's one of those things I'd like to know why or understand what's going on etc

Will look forward to your maf scaling instructions

 

I think there must be a difference in the way fuel trims are displayed, depending on the ESL version - in mine (97/98 version), 1.00 is 'neutral adjustment' whereas yours sounds like 100 is 'neutral adjustment'.

Values below 100 implies that it's running rich in those cells during closed loop, so is removing fuel.

Cold weather means denser air, therefore leaner running. Subsequently, warm weather means less dense air, therefore richer running.

I reckon if you mapped your fuel map during winter when it was cold and now it's warm, what you're seeing could be perfectly fine. Definitely keep an eye on it though!

 

i'm not sure what the min/max values are on ESL for fuel trims but some variation would be expected even on a healthy car. So long as you don't get a massive spike in values somewhere then I wouldn't be overly concerned with it and just let it do it's thing.


Maf scaling is a whole other kettle of fish, easiest way I've found is to work out your AFR error (quick blast in excel) and then apply a small portion of that error to the maf scale - rinse and repeat until your seeing the results you want. Sometimes you can get a maf error if the injectors have been swapped out and you don't have the right scaling/latency values in place. As ESL doesn't have an option for latency that would mean that very large injectors would be better off in SD setup rather than MAF to work around it.

 

Cheers for input guys , what concerns me is the fact before I did a reset the other day the fuel trims were in the 100s , I was driving in this warm weather still . On a reset they are now in the low 90s , so to me that says the fuel trims don't learn after a while as if they did they should of been in the low 90s before the reset ???

 

I always thought that the fuel trims were there for driving style and changes in fuel quality?
Much the same as knock control.
Going from 1.00 to 0.95 for example wouldn't be that much of a change in fueling would it?

 

I guess I'm wondering if when the fuel trims were 104 in the winter and now they are 92 in the summer etc is this going to make the car any different power wise or is it just adjusting to make the car the same power as it was in the winter ?

And do we need to reset fuel trims come winter / summer as they don't seem to adjust on the fly once set

 

Just seen your post osset , hmmmm not sure , are they ?

I'm due a fuel top up so can monitor with new fuel this week

 

From what I've seen on my trims,fuel&knock that they are always changing,only by small amounts.
I would think if you saw a big change then this would indicate a problem.
Going from 1.04 to 0.94 isn't a big change and just shows it's doing what it's supposed to(that's how I see it anyway)

 

Hmmmm if that's how it does work makes sense bud , just I've never seen my trims as low as 89 on one of the cells and suddenly after this reset about 6 cells are low 90s

Will post up a previous trim and a current trim to show the differences although no knock is recorded

Cheers

 

Would be nice to know for sure mate,it's only how I interpreted it,I'm sure Andy or one of the guys who's been on the course can give advise?
I've never had or seen my fuel trims jump from 1.04 to 0.80's.
I still don't think this would be a big change in fueling but I could be wrong?

 

I mailed Andy but no reply .........

I will fill up tonite and reset fuel trims and have a jaunt the way home , cooler air and fresh fuel and see what happens but car drives fine with the lower fuel trims but I like to know why they change so much etc , always good to understand what's going on etc , it first help the cells are green at 100 and above yet they go red when into the 90s and below , red means danger lol

 

Lol yeh red isn't usually good but red in the fuel map is rich so makes sense if trims are pulling fuel.
Let us know how you get on with a reset and jaunt.
Wish I could go for a blast,bloody missing mine
Should have it running next week.....fingers crossed

 

Reds lean in the fuel map, green is rich bud :-)

When you get back in yours it will feel like a new beast lol fingers are crossed for you

 

Not for fuel trims - red is for the lower values, green is for higher. Less than 1 (100 in your case) is removing fuel (e.g. too rich). More than 1 (again, 100 for you) is adding fuel (e.g. too lean).

Example of mine (97/98 ESL) from a few months back where it's lean and adding fuel to compensate:



I haven't seen the earlier version of ESL, so it may differ.

 

All mine when at 100 are green before adjustment , i see from yours, when at 100 ( or 1 ) they are red

The way i understood it, when red or 0.99 and below, fuel has been reduced which makes for a lean cell (red) and when above 100 or 1, fuel has been added making a rich cell (green)

 

But i suppose the reason why it went green or red is the reversal of how im looking at it, and how you guys are explaining it, so if a cell is red, it means the car WAS rich and if a cell is green, its means it WAS lean

 

I think the green/red thing is a bit of a red herring actually. It just takes a look at whatever the highest and lowest values are and then sets the range of values from red to green, lowest to highest. The colours are only actually relative to whatever the values you happen to have in the cells.

It just so happens that as all mine are pretty much positive trims, 0.99 is the lowest value and therefore reddest and 1.09 is the highest value and therefore greenest.

In your case you've got a mixture of positive and negative trims where 97.3 is the lowest, reddest and 106.17 is the highest, greenest.

Hope that makes sense! Ignore the colours and looks at the +/- the 'neutral' value (1.0 or 100 accordingly) to determine rich or lean.

EDIT - just to add: Think of the +/- as to whether the ECU is having to add, or subtract fuel based on the information it's getting from the lambda sensor, to try and bring the readings back in line with the values it's supposed to be hitting from the fuel map. It's adding fuel to compensate for lean, or removing fuel to compensate for rich.

 

Yup, cheers bud it all makes sense

Thing is , as the fuel trims are for mainly closed loop , it's getting readings from lambda and compensating rich or lean to get to stoich i'm assuming , under closed loop what can be altered to correct in the map or hardware to help bring the fuel trims closer to 100 or 1 ?

When I reset car runs pretty lean for a while until fuel trims get richened

All good fun lol

 

I ran mine in closed loop and used the wideband to get the trims closer to 1.00 but I know you don't have that option.
When I go into closed loop I get lambda cel,so would you unplugging your lambda be the same as driving in closed loop?

 

Hmmm, not a bad shout that, if i unplug lambda and see what my wideband readings are and then adjust the fuel table accordingly , but then, when i plug lambda back in, will it read fuel table or still use its own voltage for fuelling ?

hmmmm

 

Worth a try,I would think if you get closed loop closer to 14.7 then the trims would get closer to your 100.00?

 

Does the ECU trow a cell if you unplug the lambda?

 

I'd have thought just unplugging it will result in it it permanently reading lean. The signal is a sine wave, between 0.2 and 0.8v. If you managed to get it to always receive a 0.45v signal then it should read that as stoichiometric and might be equivalent of closed loop disabled. In theory..... ;-)

 

It Does but like I said,when you switch to closed loop on v3/4 it chucks a cel anyway.

 

when the ECU doesn't get a reading from the sensor it throws a CEL as it knows it's busted - from my understanding when closed loop is active the ECU will attempt to reach 14.7 for any fuel target cells reading 14.7 or leaner. The corrections from the MAF scale (or the invisible VE table for speed density) to get back to 14.7 are then stored in the correction table for future use.

Your doing it the same way I would, disconnect the stock sensor (or set closed loop disabled in the map to save unplugging the sensor) and then do your best to get to 14.7 for the cruise and idle cells then re-enable closed loop and let it take care of the rest. If you can't get to 14.7 then I would opt to be a little richer rather than a little leaner in the event that the o2 sensor fails whilst your out on a long cruise.

 

so if the voltage is constant then the reading on the wideband is also constant and not swinging like it normaly does in closed loop.

 

I am going to try and use a constant 0.45V to test it out.
Maybe use a switch to select the lambda sensor signal and the fixed 0.45V.
I think the ECU eventualy wil go in limp mode if the sensor is disconnected.

 

if you want to disable the sensor why not just disable closed loop in ESL though?