Idle RPM drop after morning start

[viktorhanacek]

Hey guys, did anyone of you have any experience with this RPM drop? It happens in 4 of 5 morning starts (meaning that the car was off for a lot of hours). After I start it and drive it, I can start it numerous times that day without any problem.

(ignore those two sound gaps in the end, it's bluetooth handsfree connection)

[HPIA4v2]

Looks like you have misfires, hard to say but without impending CEL (Check Engine Light), at that mileage replace the spark plugs, if it persists replace ignition coils, if still persist yet go get code reader in case you have leaky injector.

I always start from the cheapest.

GL

[ajob]

At startup my F85 does it often but not always and I have not found out what external environment may cause it, humidity, fuel type, temperature, whatever.

Car now with 95.000 km, no ill effects, 30 seconds after start the rpm always revert to normal and that's it for the rest of the day.

Suggestion: ignore it -- but if you can associate it with a probable cause, please let me know!

[P1]

Happened to my 35i for a few months, until finally one of the injectors failed. Ever since the injector was replaced, I haven't had the issue anymore.

[viktorhanacek]

Thanks guys! Tomorrow I'm heading to a dealer in Austria to a check, I hope they'll figure it out and that it will be repaired under the Premium Selection Garantie.

My other BMW service shop (not authorized dealer) said it could be (English is not my native language so I don't know if I'm using the exact or right terms) "idle valve" or any air leak from a higher pressure in air circulation that is made by something like "air pump" (higher pressure = higher rpm after start, air leaks = rpm drops?).

Maybe they'll tell me more tomorrow.

My opinion or feeling when this happens is that the car is suffocating so for me it makes sense.

Ad environment: on my car this happens only when the temperature is above let's say 15°C. Now, when winter is coming and with temperatures around 5-8°C it doesn't happen because the start RPM is so high that it cannot drop. Also I can start the engine ten times that day (even when the engine is cold) and everything is working perfectly without any drops.

[viktorhanacek]

Just got back from the Austrian dealer. They said they fixed it, unfortunately not under the Premium Selection Garantie No part changed, only new software in control and DME units. I hope it's fixed.

[viktorhanacek]

Okay, now we have that temperatures around 15-19C back and the problem is back as well.

I have bimmerlink app, do you think I can read something helpful from there?

[640ijims]

Try two ,back to back ,bottles of CHEVRON -Techron Complete Fuel System Cleaner ,worked for me

[viktorhanacek]

I tried several cans of BG K44, last one 3 months ago so I think this needs something more than this 😐

[zebka2019]

I have the same problem. My 2018 x5m has only 28k miles and I get rpm jumps on cold starts every day. Anybody found a fix?

[zebka2019]

Originally Posted by zebka2019

I have the same problem. My 2018 x5m has only 28k miles and I get rpm jumps on cold starts every day. Anybody found a fix?

https://youtube.com/shorts/UE496Ue4jsQ?feature=share

Not how to upload videos to forum but here's the link to YouTube.

[640ijims]

If you talking about the jump to 1200rpms at start up and then settling down to about 700rpm, that is the fuel system loading the catalytic converters and getting them hot. If it is going up down stumbling on start up , as I offered earlier Two cans of 16 oz Chevron Techron fuel clean , one each with two successive fill ups.

[Garcia_f24]

what kind of tune are you running? I had the exact same problem, only mine would stall. I turned of cold start in bootmod3 and the problem went away. it still jumps a little on cold starts but its so minor I dont even notice it. just my 2c

[viktorhanacek]

Originally Posted by 640ijims

If you talking about the jump to 1200rpms at start up and then settling down to about 700rpm, that is the fuel system loading the catalytic converters and getting them hot. If it is going up down stumbling on start up , as I offered earlier Two cans of 16 oz Chevron Techron fuel clean , one each with two successive fill ups.

lol see my video if you’re not sure what I try to fix. And I already said that fuel cleaners not working for me.

Originally Posted by Garcia_f24

what kind of tune are you running? I had the exact same problem, only mine would stall. I turned of cold start in bootmod3 and the problem went away. it still jumps a little on cold starts but its so minor I dont even notice it. just my 2c

No tune, everything stock, new coils + plugs. I’m also thinking about BM3 and disabling cold start. But I’d like to know where is the problem… 🧐

[640ijims]

Looked at your video, evidently I looked at wrong one at first, that is exactly what my F85 was doing and it cured with Chevron Techron…sorrry! Perhaps it is available fuel? IMHO

[Herofmine]

Same exact problem I had on my F10 M5 after removing cold start, I think that was the cause on my M5. Never seen such issue on my x5m (never been tuned, bone stock)

[zebka2019]

Can you please explain in details what Bootmod is and what is cold start in bootmod and how it functions?
I know what the actual cold start is lol , just trying to understand things properly.

I dropped my car at the dealer. They've been working on it for the past 2 months, I couldn't be any more patient.
They told me at first that they ran all tests (which later I found out was just a simple Ista scan), and checked PC Ventilation system for leaks with smoke machine and found 0 problems. Told me that it is how it supposed to work, which I called BS!
I threw keys at them and told them I'm not picking this car up until they fix that.

After a week I got a call from mechanic at bmw saying that they spoke to North American M division team and they instructed them to replace injectors.

I will keep you guys posted what happens next and if it fixed the issue

Oh and by the way, the dealer mechanic dudes are trying to be smart asses and warm up the car before I arrive there so whenever I start the car the problem doesn't replicate and therefore call their job successful

[Garcia_f24]

Originally Posted by zebka2019

Can you please explain in details what Bootmod is and what is cold start in bootmod and how it functions?
I know what the actual cold start is lol , just trying to understand things properly.

I dropped my car at the dealer. They've been working on it for the past 2 months, I couldn't be any more patient.
They told me at first that they ran all tests (which later I found out was just a simple Ista scan), and checked PC Ventilation system for leaks with smoke machine and found 0 problems. Told me that it is how it supposed to work, which I called BS!
I threw keys at them and told them I'm not picking this car up until they fix that.

After a week I got a call from mechanic at bmw saying that they spoke to North American M division team and they instructed them to replace injectors.

I will keep you guys posted what happens next and if it fixed the issue

Oh and by the way, the dealer mechanic dudes are trying to be smart asses and warm up the car before I arrive there so whenever I start the car the problem doesn't replicate and therefore call their job successful

If you are stock, bootmod3 wont help you. Bootmod3 is a flash tune that gives you the option to ​turn off cold start, and turn off upstream O2 sensors if you have catless DPs.


You may want to take it to someone that can diagnose the issue and verify it, rather than just change random parts. They should take a look at your fuel trims to see if its running rich/lean , do they go back to normal under load, etc

[viktorhanacek]

My update: during the summer I used several cans of fuel cleaner BG K44 and stopped babying the car. I started enjoying the car more just to get the engine healthy and by riding it hard no carbon have a chance to stay in the engine.

After all this I got only one idle drop this fall season (for me it's temperature related: summer, heat = no problem; winter, cold = no problem; drops occurs only with temperatures around 15•C).

[dr_greenthumb]

Originally Posted by viktorhanacek

My update: during the summer I used several cans of fuel cleaner BG K44 and stopped babying the car. I started enjoying the car more just to get the engine healthy and by riding it hard no carbon have a chance to stay in the engine.

After all this I got only one idle drop this fall season (for me it's temperature related: summer, heat = no problem; winter, cold = no problem; drops occurs only with temperatures around 15•C).

Any chance you have fixed this issue, I am working on the same problem. We have had temperatures drop and the issue seems to be getting worse.

[viktorhanacek]

Try a fuel cleaner several times and ride it hard. It's one of the options.

[viktorhanacek]

See also: https://www.bimmerpost.com/forums/sh...php?p=28029018