[E92William]

Alright so my car has been doing this weird thing at idle not directly after flashing the bimmerlabs mafless tune but a few days after. It basically starts fine then revs up a couple times and settles down and drives and idles perfectly after that. With the 330i file flashed however it liked to start up and rev all the way to 2k at first then settle down. It only does this after sitting for I'd say more than 6 hours.

I talked with @aphael from here on ig and he was having a similar issue a bit after flashing so decided to make a thread. I was wondering if anyone else has had these kind of problems with this and if it might be tune related.

Here's a video of what it does. Sometimes it'll rev higher and more than once. The fuel trims change up as soon as it starts revving up. Could this be related to the fact that I have the mafless tune while still having a physical MAF sensor? Could it be a vanos issue on cold start? I'm installing ISTA so I can run vanos actuations on my car.

These are all the codes I have. The disa valve code (last one) is because I was testing rebuilt disa valves so disregard it.

[hassmaschine]

I'm not seeing anything here in the video, it looks completely normal. Cold start RPM, specifically when the engine first starts, will always be higher than idle speed.

There's a curve on basically every ICE calibration in existence, with temperature vs additional fuel and extra "idle air" or "start throttle", with both increasing as temperature decreases. This is due to at colder temperatures, fuel doesn't burn very well (much of it just pools on the cold surfaces) and you need a much richer mixture (and more air/throttle) to start/run.

Also, modern engines try to heat the cats as fast as possible, to reduce emissions - paradoxically, that means a richer mixture on cold starts.

As far as codes, 2FA3 can be permanently cleared by default coding the DME - but otherwise has zero affect on the engine. The other codes are unrelated to the tunes.

If you have the MAF, no it doesn't matter. It has the same IAT - it just doesn't use the MAF signal.

[E92William]

Originally Posted by hassmaschine

I'm not seeing anything here in the video, it looks completely normal. Cold start RPM, specifically when the engine first starts, will always be higher than idle speed.

There's a curve on basically every ICE calibration in existence, with temperature vs additional fuel and extra "idle air" or "start throttle", with both increasing as temperature decreases. This is due to at colder temperatures, fuel doesn't burn very well (much of it just pools on the cold surfaces) and you need a much richer mixture (and more air/throttle) to start/run.

Also, modern engines try to heat the cats as fast as possible, to reduce emissions - paradoxically, that means a richer mixture on cold starts.

As far as codes, 2FA3 can be permanently cleared by default coding the DME - but otherwise has zero affect on the engine. The other codes are unrelated to the tunes.

If you have the MAF, no it doesn't matter. It has the same IAT - it just doesn't use the MAF signal.

Well yeah I understand that I'm just saying what you see when it starts up it has a set idle rpm and then it quickly revs up for a second then back to that same idle rpm. In this video it's not noticeable but sometimes it'll have those jumps on cold start up to like 1500 or so up and down a couple times. Was just wondering why it did that as it had never done it before.

I wonder if the cold start sequence is different on the mafless tune or there's something it doesn't like and reacts to that by raising the idle quickly and then back down. Maybe it's meant to be at a bit higher rpm at cold start and it isn't doing it idk.

[hassmaschine]

No, no cold start or even idle settings are altered.

[HydroxFrost]

Mine does something similar and more rapidly when I start the car and hold my foot on the brake but I always felt like that had something to do with a brake booster check valve issue.