Idle RPM drop after morning start

[viktorhanacek]

Just reporting it's still not fixed. Fall temperatures are here again and start idle problems are back as well. 🙄

[Herofmine]

I had same issue, recently and apparently it's a bad gas.

Filled the tank with 5 gallon of race fuel 104 octane + 93 racetec fuel.

No more issues.

[640ijims]

Can ( 16-20 oz) of Chevron Techron in two successive fill ups of gas

[zebka2019]

I have same exact problem. Dealer replaced injectors, coils and spark plugs, i thought it fixed the problem but after some time it started again. I purchased endoscope and just found scratches/scoring inside cylinder walls. That's what causes this RPM drop during cold start

Check your cylinder walls guys

[Blue By You]

Originally Posted by zebka2019

I have same exact problem. Dealer replaced injectors, coils and spark plugs, i thought it fixed the problem but after some time it started again. I purchased endoscope and just found scratches/scoring inside cylinder walls. That's what causes this RPM drop during cold start

Check your cylinder walls guys

Someone else on here has that same issue with scoring. What scratches the cylinder walls?

[KLR X5M]

I've posted my extensive testing, which concluded that is a fueling problem. Afr bounces tremendously while this is occurring. Has nothing cylinder walls. It only happens at certain ect ranges. Colder, not a problem. Warmer not a problem. In the Goldilocks zone will blip up and down until it becomes too lean and stalls out. I've chase idle air eaks, tested injectors fuel pumps, compression, replace coils, mafs, tested and reset adaptations on vanos and valve tronic, adjusted idle speed etc. Also did injector flush, and Overall idle quality is better, but the afr blipping still happens occasionally. I have recently found that injector compensation values seem to be missing from ecus when I read them out in ista. In going to recode the oem offsets and see if that helps. I also have 1 lazy Downstream o2 that I'm going to replace just out of curiosity.

Anyhow, this happens on all platforms with s63tu, and no one has ever conclusively diagnosed and specifically resolved. Just anecdotal experience. I Beleive it could actually happen for a variety of reasons, but I'm sure I've diagnosed this now more than most and don't have a smoking gun yet.

[zebka2019]

Does anybody know how to check leaky injectors with ISTA or any other method besides removing spark plug and inserting endoscope and looking up at injectors?

[slow_roll]

depends on how bad the leak is... one thing you can do is remove all the spark plugs, put some paper test strips deep enough in the plug openings and let it sit overnight.. check the paper strips in the morning for signs of fuel

[Chilled]

Originally Posted by Blue By You

Someone else on here has that same issue with scoring. What scratches the cylinder walls?

Crappy Cylinder Walls, Couple that with high power and long periods between oil changes. = Scoring.

A friend put me onto these vids, they are in Russian, translate works.

This one they are doing a reliability comparison of X5M vs ML63. At 11:17, they start talking about that most of the issue start after tuning and as these motors are already at their limits.
He mentions that the scoring could be caused by the higher compression ratio compared to the previous generation of S63(E70) and the newer S63T4.


For giggles, here is a vid with some scoring of an engine that has done 150km, been flatlined everyday, with oil changes 3-5k. In Russian again, and yes this is the same guy that put the ZF 8speed in his e70.

[KLR X5M]

Originally Posted by zebka2019

Does anybody know how to check leaky injectors with ISTA or any other method besides removing spark plug and inserting endoscope and looking up at injectors?

In ista, search for the misfire detection abl. It will run through tests for injectors, hpfp, and coils.

[zebka2019]

Originally Posted by KLR X5M

In ista, search for the misfire detection abl. It will run through tests for injectors, hpfp, and coils.

Thank you, will run this test.

[Beamerx5f15]

2018 bmw x5 mine does exact same thing rpm drops down then goes back up at cold start meaning vehicle set all day or half day without being driven what could possibly be?

[yasavguy]

Mine just started to do the same thing - rpm drop at cold start, albeit it is not as harsh as in OP's video.

Spark plugs were replaced 1.5 years ago. Didn't do coils/injectors though.

[FirstBMWLA]

I disabled cold start warmup routine via BM3 tune and have never observed this issue again myself

[aussiem3]

Reviving this thread. Just bought a 2017 X6M with 61k km, and the rpm bounces momentarily, and then settles to a constant rpm when I start first thing in the morning. The weather at the moment is neither hot nor cold. If bad fuel is an issue will fill up with RON 98 and add Liqui Moly fuel system cleaner to see what happens. I have bought spark plugs and if the issue continues will change them. May be too early to do sparks at 61k km.

[ArthurMorgan]

Technically that's overdue on spark plugs, assuming the previous owner never did them. The maintenance guide (at least for the US) says spark plugs should be replaced every 30k miles (48k KM).

[Chilled]

Originally Posted by aussiem3

Reviving this thread. Just bought a 2017 X6M with 61k km, and the rpm bounces momentarily, and then settles to a constant rpm when I start first thing in the morning. The weather at the moment is neither hot nor cold. If bad fuel is an issue will fill up with RON 98 and add Liqui Moly fuel system cleaner to see what happens. I have bought spark plugs and if the issue continues will change them. May be too early to do sparks at 61k km.

Double check the idrive, if it was fully taken care of by BMW. The plugs would of been done by now. Mine got done at around mid/high 30s'KM, based on service schedule/age.

[aussiem3]

So, interestingly, I went to buy spark plugs the day I picked up the car, and the service manager gave me a set at half price, not bad. I am waiting for the tools to arrive before undertaking the task.

Thanks all for the heads up. Didn't realise it was serviceable part as early as 30k km.

[Chilled]

I think mine was more of age/ Idrive says its the 3rd/4th service, etc. and now the plugs are due. Not really a KM thing.