Transient fuel GUFX

[PaulC-turbo5.0]

So there’s either something wrong with my car or I still don’t understand how to dial in fuel after all this time?! My fuel error will change a bunch depending on the temp outside and how long I run the car. Am I correct in understanding that I should be able to get the error and kams dialed in to stay between 1 and 1.03 at literally all times? Meaning whether the car has ran for 20 mins or 5 hours in 30 degree or 90 degree weather? I am even seeing different errors in different gears. 3rd & 4th will be consistent but 5th will usually be adding more fuel at the same maf point.

[decipha]

nope some engines arent consistent but it sounds like you have a dirty maf

[PaulC-turbo5.0]

Ok I’ll give cleaning it a shot but I have a feeling I have one of those engines.

If I can’t get it to be more consistent should I still aim to always have the trims above 1? This is how I’ve been doing it but then I deal with it adding as much as 10% sometimes. Or would I be better off having it between 1.05 and .95.

[decipha]

better to have it only add and not remove

[dleach1407]

Also like you mentioned my maf transfer needed adjusting but as usual its still fucking with me?! Driving it for a while yesterday after loading the tune it was adding a bunch of fuel, up to 10% in some spots. I worked it for a while dialing it in. Well to no surprise this morning driving in to work its pulling that much fuel?! I stopped shut the car off and loaded in the old maf transfer and the damn thing was still pulling fuel after.

This is my experience with the fuel error too. Fuel error when cold will be pulling 10% then when it gets hot, its adding 5 to 10%. I experienced the exact same thing today while trying to dial in fuel. Its a constant back and forth fight to get fuel error dialed in. add 10% this week, remove 10% next week

[PaulC-turbo5.0]

Yea it sure is frustrating! I have no idea how my my trims were before turbo but ever since I’ve went turbo it’s been like this. With the shit tune from the first guy that was in open loop the car would actually run rich and lean to where I could see it in the WB!

I think I’ve finally got some clarity on it now from decipha. I plan to have mine dialed in within the first half hour or so of run time and then just leave it. I’ll deal with it adding a lot at times but so be it. Start driving it without the laptop and just enjoy it more. I find it’s a lot more enjoyable to drive when I’m not obsessing about how perfect or not perfect it’s running.

[decipha]

theres supposed to be a fuel error on a cold engine if your using that data then your going to be off everytime

as long as you hold each point stable and 0 out that error at that point before moving to the next then youll always be perfect

[PaulC-turbo5.0]

Should the error when cold be negative or positive?

I’m not using that data for adjustments. If I get the error zeroed out if the cars been running 30-45 minutes it will change when it runs for another hour. The more heat soaked the car gets the more fuel it adds to maintain stoich.

I even see this with startup enrichment. If I start the car cold and get it to 150 degrees and shut it down and restart it, it will be rich. If I run the car for a while and shut it down for say a half hour and it cools to 150 when I restart it, it will be lean.

[decipha]

cold should be all over the place

that means your fuel pump is too big

[PaulC-turbo5.0]

That’s interesting. I did have a 320lph in originally that was overpowering the regulator at idle so I dropped down to a 255lph. A 255 shouldn’t be too big though?