Very high LTFTs

[tomasidris]

Been chasing very high ltfts for years now on my 02 M3, with it progressively getting worse over the years. When I got the car it was around 8% and 10% in either banks and as of late its sitting close to 18% and 20%. I have tried virtually everything to find the culprit with no luck, i have yet to smoke the evap system and test the purge valve which are really my final options. I took a datalog just now to test out new o2 sensors I just installed, the originals with ober 230k miles were still being used so I figured it was worth a shot. If anyone could look over the data log which has a couple minutes of idling, a 3k rpm hold, and a couple of wot revs, Id appreciate it thanks! https://datazap.me/u/tomasidris/log-...2?log=0&data=8

[Darbshaw]

Have you done a leak down or compression test? I don't want to stir thoughts of doom but I was chasing this and a high rough running stat. It ended up being a blown head gasket that required a full rebuild.

Given your mileage I'd say it's likely that you could be facing that issue. It's worth checking. Mine was split between all but 5-6

[sapote]

Precat O2 B1 is bad (barely switching), and B2 is also very tired. You don't have postcat sensors connected?

The MAF also a bit low at 4g/s at hot idle. Should be around 4.5
Also the log doesn't have enough data -- the sampling is too slow. For the Logging Trigger > select the Trigger on PID frame instead of trigger at fixed sample time.

Have you measured the fuel pressure while idling?

[tomasidris]

Have you done a leak down or compression test? I don't want to stir thoughts of doom but I was chasing this and a high rough running stat. It ended up being a blown head gasket that required a full rebuild.

Given your mileage I'd say it's likely that you could be facing that issue. It's worth checking. Mine was split between all but 5-6

Yea i think that was my next thought, just dreading the results haha. Will get on that

[tomasidris]

Precat O2 B1 is bad (barely switching), and B2 is also very tired. You don't have postcat sensors connected?

The MAF also a bit low at 4g/s at hot idle. Should be around 4.5
Also the log doesn't have enough data -- the sampling is too slow. For the Logging Trigger > select the Trigger on PID frame instead of trigger at fixed sample time.

Have you measured the fuel pressure while idling?

Mafs been replaced not too long ago and cleaned recently, and those o2 sensors were just replaced which is great lol. Post cat i dont run since im catless, and I have a radium filter and fpr along with a dw200 pump and pressure is set at like 52 psi during idle.

[sapote]

Mafs been replaced not too long ago and cleaned recently, and those o2 sensors were just replaced which is great lol. Post cat i dont run since im catless, and I have a radium filter and fpr along with a dw200 pump and pressure is set at like 52 psi during idle.

Something is wrong as the sensors should be switching more than just a few in 4 minutes as pic below:

[tomasidris]

Something is wrong as the sensors should be switching more than just a few in 4 minutes as pic below:

Yea idk could be an exhaust leak around the sensor or its just a dud, ill do a smoke test of the exhaust tmrw and another log with the settings you recommend and some more pids.

[BL92]

This hose is split !

[sapote]

Yea idk could be an exhaust leak around the sensor or its just a dud, ill do a smoke test of the exhaust tmrw and another log with the settings you recommend and some more pids.

Don’t add unnecessary pids as this will slow down the sampling time. You already have the important ones.

[tomasidris]

Don’t add unnecessary pids as this will slow down the sampling time. You already have the important ones.

Sorry i meant I changed the pids, added calculated load and removed some of the unnecessary ones.

[tomasidris]

This hose is split !

I have a catch can and smoke test already performed with no leaks found

[tomasidris]

Well this could definitely cause some issues 😅 Must’ve installed it wrong last time i had the plenum off. Dont think this will be the end of my problems though as I have been having these high trim issues for a while now. Also curious on how my new maf looks different from my original, I confirmed the part number online. Do you know if they changed the design?

[sapote]

That messed up boot sure caused the low MAF reading

[tomasidris]

That messed up boot sure caused the low MAF reading

Yeah, still confused on the brand new o2 sensors though. No leaks in the headers at all, could they simply be faulty?

[sapote]

Yeah, still confused on the brand new o2 sensors though. No leaks in the headers at all, could they simply be faulty?

Double check the pid trigger sampling time: every 1sec, or pid frame? Slow sampling time can cause missing pulses on O2 sensor signals (and other pids).