NefMoto

I am getting started on tuning my B5 S4. I read through the community tuning post for the 2.7 and am using that stage 2 file as my base file. Starting with tweaking the fueling (put in the ford injectors) I am running into an issue with the fuel trims in VCDS. When I log block 32 at idle I get nothing. I understand there shouldn't be any long term numbers but I haven't seen anything for short term even after idling for quite some time and then driving around for another 10-15 minutes.

I've tried diagnosing the O2 sensors, replaced the MAF with a new one, and haven't found anything that would explain why it's not reading any data. Where is this info coming from and how can I fix this issue? Never seen this before on any forums or elsewhere, only wrong numbers so I'm finally posting a question hoping someone will have an answer.

Thanks

I assume you mean block 32, and yes, it should always be showing data.

Does flashing a stock file behave the same?

Thanks for the reply nyet. I just did a fresh flash of a M-box file onto a different ECU and I am still getting the same readings, nothing. I'm planning on rebuilding an engine wiring harness soon because I have found and repaired several spots that were wrecked from age and heat but from some of the tests I've done per the Bentley I can't find anything that would be causing the faulty readings. Not sure of the next steps to take to diagnose it. What sensors are being used to generate the fuel trim readings?

I would be shocked if you aren't seeing DTCs.

Just about everything is used to generate fuel trim readings, but primarily O2 sensors obviously.

The only code I have not been able to get rid of yet is this one:

17650 - Fuel Injector for Cylinder 6 (N84)
            P1242 - 35-00 - Open Circuit

Followed the diagnostics for checking the wiring, and injector and they're all within spec. When I briefly swapped #5&6 injector wiring connectors the code went to cyl #5 so it's obviously a problem in the wiring even though it's in spec. Another reason to replace the harness and hopefully clean up any electrical gremlins.

With only one cylinder not quite right I would still expect to see something reported even if it were way off...

you answered your own question

If I wasn't clear before when I say I am not getting any readings I mean none at all on all 4 boxes for that entire block. Seems unlikely that that one code for injector #6 would have any effect on bank 1. There has to be something else going on for there not to be any readings.

Stop assuming shit and read the FR.
Injector fault = obviously lambda control off.

Why are you even looking at fuel trims when you have an injector open circuit?

It wasn't there before I put the injectors in. While I was swapping them I noticed the wiring on the O2 sensor was broken. Repaired that and checked the FI & O2 wires again per the Bentley. So you're saying that with the open circuit fault, the computer just won't report anything for the fuel trims? I am getting a reading from the MAF, and readiness codes from the O2 sensors.

What is the FR I should read?

Its cited pretty much everywhere, links are in the faq sections here AND on the tuning page.

That said, prj is somewhat overstating its utility for novices. Until you get fully caught up you will likely have to rely heavily on others citing the FR for you (and that means you never know who is right or wrong)