[M_174]

Hi everyone,

I had my car for about 6 months and I always drive it fast on good highway roads outside the city. Last weekend, my car started suddenly to cut power at RPM higher than 5000 and if I kept my foot on the paddle when it cuts power grey smoke started to come out of the exhaust I can see it in the mirror!

I was using pump fuel 95 about half tank when this happened, I refilled the tank when this happened and tried again, same issue happened again.

I drove my car back home, on low RPM/ normal city driving the car is totally fine.

I have an appointment at BMW next week as the car is under warrranty but I wanted to get your opinion on what this issue could be and if anyone faced something similar.

It feels like something fuel related as the car drives normally on lower rpm.

[SE7EN335]

Originally Posted by M_174

Hi everyone,

I had my car for about 6 months and I always drive it fast on good highway roads outside the city. Last weekend, my car started suddenly to cut power at RPM higher than 5000 and if I kept my foot on the paddle when it cuts power grey smoke started to come out of the exhaust I can see it in the mirror!

I was using pump fuel 95 about half tank when this happened, I refilled the tank when this happened and tried again, same issue happened again.

I drove my car back home, on low RPM/ normal city driving the car is totally fine.

I have an appointment at BMW next week as the car is under warrranty but I wanted to get your opinion on what this issue could be and if anyone faced something similar.

It feels like something fuel related as the car drives normally on lower rpm.

It sounds like the car is detonating at higher rpm due to insufficient octane. Your DME would have knock sensors to detect those detonations (knocks) and be constantly pulling timing, thus the cutting of power that you are feeling.

And when you say pump 95? Do you mean 95 AKI or 95 RON? 95 RON and driving it hard like you stole it wouldn't go down well.

[M_174]

Originally Posted by SE7EN335

It sounds like the car is detonating at higher rpm due to insufficient octane. Your DME would have knock sensors to detect those detonations (knocks) and be constantly pulling timing, thus the cutting of power that you are feeling.

And when you say pump 95? Do you mean 95 AKI or 95 RON? 95 RON and driving it hard like you stole it wouldn't go down well.

In my country we have 91 and 95 options only, I am not sure RON or AKI my car is stock and this is the fuel recommended by the dealership.

The cutting of power is accompanied by huge smoke.

Is it safe to drive the car to the dealership at low RPM? Or should I have it trasportrd to dealership?

[SE7EN335]

Originally Posted by M_174

In my country we have 91 and 95 options only, I am not sure RON or AKI my car is stock and this is the fuel recommended by the dealership.

The cutting of power is accompanied by huge smoke.

Is it safe to drive the car to the dealership at low RPM? Or should I have it trasportrd to dealership?

Just did a search for Saudi Arabia fuel and it looks like you guys only have 91 and 95 RON.

I personally wouldn't drive it hard on 95 RON, as the DME would constantly pull timing. From personal experience, I have previously filled up on my F80 M3 from empty using 95 RON at a remote location where they didn't have 98 RON at all. As soon as I pulled out of the fuel station onto the highway, I could feel a substantial decrease in power. I imagine it would be the same on the G8X.

I think it is safe to drive the car to the dealership as long as you avoid high rpms, which is where the detonation occurs.

Do you have any octane booster in your country? I personally would throw in a bottle of octane booster on a full tank and see if the problem disappears. If it does then it is because of low octane.

[M_174]

Originally Posted by SE7EN335

Just did a search for Saudi Arabia fuel and it looks like you guys only have 91 and 95 RON.

I personally wouldn't drive it hard on 95 RON, as the DME would constantly pull timing. From personal experience, I have previously filled up on my F80 M3 from empty using 95 RON at a remote location where they didn't have 98 RON at all. As soon as I pulled out of the fuel station onto the highway, I could feel a substantial decrease in power. I imagine it would be the same on the G8X.

I think it is safe to drive the car to the dealership as long as you avoid high rpms, which is where the detonation occurs.

Do you have any octane booster in your country? I personally would throw in a bottle of octane booster on a full tank and see if the problem disappears. If it does then it is because of low octane.

Yes we do, octane booster and pure octane are both available. I’ll try it out and see.

I am in Saudi and you would imagine we should have the best fuel in the world but unfortunately it’s not the case.

[windnsea00]

95 RON is close to 91 AKI, the highest we get in California, minus the rare and very expensive 100 AKI racing gas.

[M_174]

I had the car checked in a workshop and it seems there is an issue with high pressure fuel pump.

Speaking with local BMW customers another one also M4 G82 is facing a similar issue but he got an alarm and car is restricted at 3000 rpm.

Anyone here faced similar problem? I don’t see many reports on it.

[SE7EN335]

Originally Posted by M_174

I had the car checked in a workshop and it seems there is an issue with high pressure fuel pump.

Speaking with local BMW customers another one also M4 G82 is facing a similar issue but he got an alarm and car is restricted at 3000 rpm.

Anyone here faced similar problem? I don’t see many reports on it.

Haven't heard of any HPFP issues happening on a stock tune S58 or even B58. Seems very strange...

I'm running on JB4 Map 4 E35 mix with no issues on the HPFP. My friend is running on custom E85 flash tune and also no HPFP issues.

Did you try the octane booster or filling up with a few gallons of E85 to see if the problem still persist?

[M_174]

Yes I added octane booster, the amount of smoke reduced significantly but the power still cuts.. it feels as if traction control is interfering

I also tried with traction fully off just to check if it is a traction issue but no change

[SE7EN335]

Originally Posted by M_174

Yes I added octane booster, the amount of smoke reduced significantly but the power still cuts.. it feels as if traction control is interfering

I also tried with traction fully off just to check if it is a traction issue but no change

Gray smoke out of exhaust usually indicates fuelling problems. If there is less gray smoke, the extra octane definitely helped with that.

I would get it checked out by a BMW dealer who will be able to check out any fault codes or even shadow fault codes on the car. And they can log the HPFP and LPFP psi, and injector fuel trims on full throttle to see if it is genuinely those components that are failing

[M_174]

Definitely, I am just asking around while waiting for my appointment next week.. thanks all for the help, appreciated

[M_174]

Went to the dealership they checked the car and they said the catylitic converter need replacement.

There is no damage from the outside but maybe something went wrong inside!

They ordered the parts from Germany and will have it installed in couple of weeks, apparently the car is not safe to drive in this condition.

[Indo Rider]

Originally Posted by M_174

I had the car checked in a workshop and it seems there is an issue with high pressure fuel pump.

Speaking with local BMW customers another one also M4 G82 is facing a similar issue but he got an alarm and car is restricted at 3000 rpm.

Anyone here faced similar problem? I don’t see many reports on it.

This thread describes similar issue only at high rpm, turned out to be the HPFP in the end.

https://g80.bimmerpost.com/forums/sh....php?t=1958719

[AHall]

Unless the catalytic converter was defective when the car was built, they have not identified the cause of your problem. Something has caused the catalytic converter to become defective. Excessive exhaust temperatures perhaps. If they have not identified the cause you will likely be back in the same boat. Especially the way you drive.