[foogaazi]

Hi guys, I've got a 2021 G82 M4.

So a few days ago I installed an full exhaust system by a reputed manufacturer and everything was fine until 2 days later.

My car would not upshift from 3rd to 4th and 4th to 5th and start jerking and bogging down. This happened only when I would upshift in 4-5-6k rpm range so on relatively high throttle.

The car drives fine otherwise on normal throttle and shifts are fine.

I got it checked with the garage and the only fault that showed was for the valve controller. Everything else seemed to be okay.

My shop is in the process of installing the stock system back on to see if it happens stock also, but just installing an exhaust shouldn't cause any problems like this on a new car?

My downpipes were also stock btw. Will update more when stock exhaust is back on, to see if it's an actual problem with the transmission rather than the exhaust.

Any advice or experience?

[ChrisM4]

Originally Posted by foogaazi

Hi guys, I've got a 2021 G82 M4.

So a few days ago I installed an full exhaust system by a reputed manufacturer and everything was fine until 2 days later.

My car would not upshift from 3rd to 4th and 4th to 5th and start jerking and bogging down. This happened only when I would upshift in 4-5-6k rpm range so on relatively high throttle.

The car drives fine otherwise on normal throttle and shifts are fine.

I got it checked with the garage and the only fault that showed was for the valve controller. Everything else seemed to be okay.

My shop is in the process of installing the stock system back on to see if it happens stock also, but just installing an exhaust shouldn't cause any problems like this on a new car?

My downpipes were also stock btw. Will update more when stock exhaust is back on, to see if it's an actual problem with the transmission rather than the exhaust.

Any advice or experience?

Were you there for the install? They didn't take it for a "test drive" / thrash did they?

[mike@x-ph.com]

Let us know if the problem if the stock exhaust fixes the problem

[foogaazi]

Originally Posted by ChrisM4

Were you there for the install? They didn't take it for a "test drive" / thrash did they?

Yes I was there for the install. It was fitted perfectly.

[foogaazi]

Originally Posted by mike@x-ph.com

Let us know if the problem if the stock exhaust fixes the problem

So after we installed the stock exhaust, issue happened like 2 times.

Driving the car later during and until now it didn't happen at all. So seems like yes the stock exhaust has fixed it.

[GoodGuyAvi]

Originally Posted by foogaazi

So after we installed the stock exhaust, issue happened like 2 times.

Driving the car later during and until now it didn't happen at all. So seems like yes the stock exhaust has fixed it.

crazy issue

[Indo Rider]

Originally Posted by foogaazi

So after we installed the stock exhaust, issue happened like 2 times.

Driving the car later during and until now it didn't happen at all. So seems like yes the stock exhaust has fixed it.

Doesn't make any sense at all. You said no problems for first 2 days after installing aftermarket exhaust. Then you had problem. Then you reinstalled stock exhaust and had the issue 2 more more times? And you have concluded that the aftermarket exhaust caused your transmission issues?

[Fugazii]

Corporate shutting you down. Sorry I had too all serious that sucks finger's crossed!

[foogaazi]

Originally Posted by Indo Rider

Doesn't make any sense at all. You said no problems for first 2 days after installing aftermarket exhaust. Then you had problem. Then you reinstalled stock exhaust and had the issue 2 more more times? And you have concluded that the aftermarket exhaust caused your transmission issues?

Originally Posted by Indo Rider

Doesn't make any sense at all. You said no problems for first 2 days after installing aftermarket exhaust. Then you had problem. Then you reinstalled stock exhaust and had the issue 2 more more times? And you have concluded that the aftermarket exhaust caused your transmission issues?

No I didn't conclude that the exhaust caused the issue. It just so happened just 2 days later after I installed the exhaust as the first mod on a stock car, so I suspected it.

Anyways, the issue persisted even with stock exhaust and the car is now with the dealership.

I will update this thread with the fix in case anybody else ever faces the same. Hopefully not!

[Chubbiejones]

Originally Posted by foogaazi

No I didn't conclude that the exhaust caused the issue. It just so happened just 2 days later after I installed the exhaust as the first mod on a stock car, so I suspected it.

Anyways, the issue persisted even with stock exhaust and the car is now with the dealership.

I will update this thread with the fix in case anybody else ever faces the same. Hopefully not!

Definitely keep us posted on the results from the dealership!

[foogaazi]

Hi guys. Dealership called today.

They said the problem is because of a faulty fuel pump - wouldn't supply enough at high throttle driving.

They said there are no error codes thrown so in practice the fuel pump is fine but it might be a micro issue thats why they're gonna replace it.

It's gonna take 2-3 weeks for them to replace it since they're ordering it from Germany, but they're sure of it - and I hope they're right.

[Mo_g82]

If not it may be something as stupid as one of your sensors got damaged during the install (it happens even with the most cautious installers now and then). It could be it's sending intermittent false readings that aren't triggering a fault but are causing the engine management system to think something is wrong.

Hopefully the pump fixes it! but if not it's definitely worth replacing them to see.

[foogaazi]

Originally Posted by Mo_g82

If not it may be something as stupid as one of your sensors got damaged during the install (it happens even with the most cautious installers now and then). It could be it's sending intermittent false readings that aren't triggering a fault but are causing the engine management system to think something is wrong.

Hopefully the pump fixes it! but if not it's definitely worth replacing them to see.

That was initially one of the theories floated by the installer actually.

Thing in UAE is that I can't tell the dealer I put an exhaust- any add ons to a car void the warranty.

Now I'm patiently waiting, let's hope the fuel pump fixed it!!

[foogaazi]

Update!

The dealer recognized and solved the issue. It actually was the fuel pump.

Anyone facing the issue I mentioned, or additionally the car makes a wheezing sound after turning the car off, check your fuel pump!

[hamadalk]

Originally Posted by foogaazi

Update!

The dealer recognized and solved the issue. It actually was the fuel pump.

Anyone facing the issue I mentioned, or additionally the car makes a wheezing sound after turning the car off, check your fuel pump!

Hi,
Im facing the same issue it started two days ago , what do u suggest

[Info@mad-us.com]

Originally Posted by hamadalk

Hi,
Im facing the same issue it started two days ago , what do u suggest

Take it to the dealer like the op did.