Crazy fuel trims !!

[Piggysniffer]

This is what I got after a sustained 5 mile run at about 90mph (on a private road) mostly in negative boost, ran fine with no knock, slowed down, did about a minute of normal driving at about 30/40got -5 flkc and -4.20 fbkc pretty much immediately which knocked IAM down to .5 then straight back up to 1, pulled learning view up and saw this, remap booked for Friday so hope it's a mapping issue, anything to check for before I go ??

[savage bulldogs]

Most of what you've written might as well be in Japanese, as I don't know much about mapping.

I'd imagine if you normally do town driving with occasional spurts of boost, the ecu would've trimmed fuel accordingly. So giving it beans on the carriage way would maybe cause the ecu to trim fuel under the heavier load in higher gears ?

Afaik it's only knock and afr differences that induce "trim" so a change in fuel ,engine load or knock limits might have caused this

If it's not broke .....upgrade it 😊

[Piggysniffer]

The real problem area from what I can gather is the -15% , that means it's taking 15% fuel out in that area and 15 is the maximum it can remove, so it is maxed out and it could maybe need to take more and can't, the other problem is, why is it needing to try and remove that much fuel, it could be the full tank of fuel and the walbro 255 that I'm not mapped for I suppose as that sent all my trims very negative after I fitted it -6/-8% across the board with the first trim being even lower down to -14 at times, the first one has always been the worst up until now, I've put a few city miles on it today and it's still maxed out at -15

[Phillip1993]

It sounds and looks like The fual map table might be out towards the high load end but there are a lot of things that control fueling

[savage bulldogs]

Strange , Unless your old pump was failing , I wouldn't have thought fitting a new pump would change the fuel pressure /trims .

Cos the fuel pressure regulator should keep the pressure the same , unless the old pump couldn't keep up with the engines demand maybe ? .

If it's not broke .....upgrade it 😊

[Phillip1993]

Could do the fuel pressure reg getting week iv not seen it happen before but you never know, you would have to put a fuel pressure gauge on to find out

[Piggysniffer]

The car was mapped at 69k by the previous owner, and at 100k I have fitted new parts like maf, plugs, panel filter, walbro, front o2 sensor, silicone turbo inlet pipe, wonder if that's thrown off the tune as it was tuned on 70k sensors ? Plus the tune is 30k and 4 years old now, is that even a problem ??, Anyway, just changed oil n filter before the mapping and found the inner cv boot has split and covered everything in grease lol

[Piggysniffer]

I also read conflicting reports on wether a walbro will muck up your fuelling, some big names say it absolutely will/does and some others say it won't/doesn't, almost seems it's different from car to car

[Phillip1993]

Did the problem happen after you changed the o2 sensor

[Piggysniffer]

I can't remember tbh mate, but I had the car remapped today and it had a bit of a lacklustre map already on it from a company called "flash remapping", it wasnt an awful map, it made 259 but had the map for the throttle pedal altered so that the driveability was bl-oo-dy awful, so I came away with it showing 276 and 40 more torques and driving like a dream :)

[Piggysniffer]

Looks like I spoke too soon, cars in limp mode