Low RPM Hard Acceleration - Pre-detonation

[Banma]

I just loaded the current tune yesterday and went for a drive. Fwiw, it felt a bit smoother across the rev range. I don't know what adjustments were made and it could be all in my head, but it "feels" nicer to drive. Thanks Alex!

[DOCTOR.Y]

For everyone who has this noise did you notice it’s happening only when car is hot? Engine oil is about 90 degree then it started.

[De_Cruelz]

Been eyeing this thread on and off for awhile now and I have the same issue on stock tune and only happens when the engine oil is warm or at operating temp. I'm in Sydney too and have only used BP Ultimate which is RON98. Octane boosters have helped ever so slightly but the ticking is still somewhat audible.

No change with new plugs installed and coil packs looked fine upon visual inspection. Perhaps this also points more and more to a VANOS issue as per OP's final conclusion but in my case on a stock tune.

Perhaps it's time to do a VANOS inspection or solenoid clean/replace?

[triplej]

Has anyone got to the bottom of this pre det? Mines started a month or so ago. Stock engine and on 98 RON fuel (Auz). Engine must be hot / @ temp. I saw someone say they changed the low pressure fuel sensor and it resolved the issue and improved idle.

[DOCTOR.Y]

Any findings mates?

[De_Cruelz]

Seems like a bunch of us in Australia are all having similar issues. I've noticed it become more prominent now with the warmer weather

[Redd]

Originally Posted by De_Cruelz

Seems like a bunch of us in Australia are all having similar issues. I've noticed it become more prominent now with the warmer weather

Do you have an OBD2 dongle and torque app? Can you log ignition advance? I'm curious if there is any ingition retardation when this happens.

[De_Cruelz]

I have the Carly dongle but have not tried it with the Torque app. Is there a subscription required to log ignition advance with Torque?

For what it's worth, adding in octane booster to RON98 helps somewhat but does not eliminate the rattle.

Injectors, coil packs, plugs have all been replaced as well with no change that I've noticed.

[Redd]

Originally Posted by De_Cruelz

I have the Carly dongle but have not tried it with the Torque app. Is there a subscription required to log ignition advance with Torque?

For what it's worth, adding in octane booster to RON98 helps somewhat but does not eliminate the rattle.

Injectors, coil packs, plugs have all been replaced as well with no change that I've noticed.

Not sure if the free version has logging since I have the paid one. You can try. Maybe Carly has that feature too.

[De_Cruelz]

Unfortunately there is no iOS version of the Torque app it seems. Might have to take a look at the Carly app again. Might also look into those standalone OBD2 units if there is ignition monitoring. Thanks for pointing me in this direction!

[Scharbag]

Originally Posted by De_Cruelz

I have the Carly dongle but have not tried it with the Torque app. Is there a subscription required to log ignition advance with Torque?

For what it's worth, adding in octane booster to RON98 helps somewhat but does not eliminate the rattle.

Injectors, coil packs, plugs have all been replaced as well with no change that I've noticed.

What tune are you running?

[De_Cruelz]

Originally Posted by Scharbag

What tune are you running?

I've had this issue when I was on stock 240E and BPM Stage 2 tune.

[pbonsalb]

I have been reading about LSPI and it is sort of scary. It is apparently less of an issue on port injection cars.

[IamFODI]

Originally Posted by pbonsalb

I have been reading about LSPI and it is sort of scary. It is apparently less of an issue on port injection cars.

I wasn't aware it was an issue at all on port injected engines. Have you heard it can be?

[triplej]

Sorry haven't been on this site for a while. I had it looked at but have lost the codes.. a long the lines "compromised charge bank 2.." The mec basically said its got a vacuum / air leak and they would need to pull the manifold off and do a smoke test...that hasn't happened yet.

[triplej]

For the records I didn't go ahead with the smoke test as I decided I was getting tugged ($3k and no guarantees!). I went back to the original place i get it serviced and they said it had something like 17 codes logged. They changed the air filter and told me even tho i was using 98RON the usual "discount" place I buy fuel was dodgy. I now use a premium brand and after two tanks.. no predet. Can't quite believe it. I had tried this previously but even a relatively small amount of the dodgy gas and a service due air filter was enough to set it off. I hope it doesn't come back!

[De_Cruelz]

What brand fuel were you on before and now? I’ve always used BP98 but the issue has persisted even with a new low pressure fuel sensor.

[triplej]

Yes BP (now) as well. There is still a slight rattle but I understand from other threads this is normal valve train noise. Before it was scary loud. I should also mention they reset all the adaptive settings for the engine. I'll keep you posted with any developments.

[De_Cruelz]

Hey triplej , how's it all going so far?

[triplej]

@De_Cruelz, No good news on the ping / pre det front. It’s still there. Seems I don’t drive it far enough or the Melbourne cold keeps it at bay, most of the time.
I have done some research and there is no clear answer that I’ve found. My usual garage doesn’t want to know about it. Southern BM tells me it could be any number of things, no guarantees they can fix it and even told me they “all do it”.
I also found a thread whereby somebody in AU confronted BMW about it and they basically told them it doesn’t damage the engine, live with it, or get another car. Great. That fills me with confidence.
My current solution is to add 1/3 of a bottle of octane boost to a 50L fill. That seems to work so far. Thats only a 0.33% mix. If this works thru summer it's the cheapest fix so far.

[triplej]

I should add, in fairness to my usual garage, they say it's a fuel issue. Problem is I cannot buy fuel that is "good" enough, hence the octane boost approach.