Logging ignition timing and LTFT - what is normal?

[cjep]

Hi

I have finally got my OBX downpipe exhaust on my car and have become interested in monitoring how it is actually going before going further. I am also running a MBC at 14psi.

I dont have any issues with the car, apart from me wanting more power out of it. And I dont really have a baseline to compare to... So I am not sure what to expect in my logs, hence my post

LTFT
My LTFT is about +8 to +10. I reset my fuel trims again (disconnect battery) and it was the same. I noticed that at idle (and I mean for over 5 min), the LTFT stays at 0. But as soon as I start to drive, the LTFT increases almost instantly, and then creeps up to almost 10.

Is this normal with a bigger DP / exhaust? If not, any ideas?

Ignition timing
At partial throttle, my ignition timing advances up to about 35 degrees.

At WOT, my timing moves back to about 15 degrees for the entirety of the pull.

I am running 98 octane fuel.

Is this normal, if not any ideas?

Thanks
CJEP

PS: I am logging using the torque pro app and an ELM OBD sensor.

[abscate]

We do have some speed heads on this forum but I think there may be better sites for performance stuff like this...anyone help on this?

[northernlights]

My long term fuel trim was about +5% on a full stock 150k mile 1994 850 turbo. The tool which I used did not specify if this was the idle or part throttle value, but in any case it did not seem to change much, if at all, during driving. I have not checked it after making modifications, but my fuel economy did increase after exhaust improvements, so the ECU is clearly doing something.

I believe my part throttle timing was in the vicinity of what you are describing, i.e. in the 30's, with very little advance under load. All these things I will check once I obtain a better tool.

The old blue books say the FT/idle adjustment happens fast (a few minutes) while the FT/part throttle takes longer. They also claim the FT part throttle has a huge working range, with a mean value of 1.00 [ and +/- 1.00(!)] with values below 0.95 being rich and values about 1.05 being lean.

Short term fuel trim can vary +/- 25% while running to maintain lambda control. This +/- 25% is from whatever the ECU has set the LTFT value to.

Here's a page of Volvo Goodness about this from the Motronic 4.3 book.