[crashoverride]

So I have a higher mileage 2006 e90 330i. It used to have a good amount of power now I'm amazed at how slow it is. In the process of refreshing things. Just ran fuel system cleaner. I'm thinking of pro actively replacing fuel pump/filter and replacing injectors. Installing new coils and plugs.

A bit later I'm looking at draining and servicing transmission with fluid, filter, sleeves and solenoids.

Any ideas what is slowing down hoping the above proactive maintenance will coax back out some missing horsepower

[WheelNut2]

How long have you had the car for? Do you have service records? Have you done any investigations into how the car is running using ISTA or INPA? Is it running smooth? It could be losing compression, or have a clogged air filter, or a number of other issues. If you have a bad coil/plug/injector the car *should* throw a code and/or run rough.

[Fireball5657]

Originally Posted by crashoverride

So I have a higher mileage 2006 e90 330i. It used to have a good amount of power now I'm amazed at how slow it is. In the process of refreshing things. Just ran fuel system cleaner. I'm thinking of pro actively replacing fuel pump/filter and replacing injectors. Installing new coils and plugs.

A bit later I'm looking at draining and servicing transmission with fluid, filter, sleeves and solenoids.

Any ideas what is slowing down hoping the above proactive maintenance will coax back out some missing horsepower

In addition to what the poster above said, I recommend cleaning or replacing the VANOS solenoids and check valves. The original ones looked pretty good on my 328i, but cleaning them at only 98k improved my idle a lot and brought a little extra power back into the car. Since yours is at 200k, I'm sure it would make a much bigger difference, even more so if you replaced them.

I'm not sure replacing the injectors and fuel pump would make much of a difference. The fuel system is pretty robust on these N52s, the fuel system cleaner should be enough. Of course if I'm wrong, someone please correct me!

Replacing the coils and plugs will make a difference if they haven't been done in a while. OEM grade coils and plugs last about 80-100k miles before they start to noticeably wear out. Replacing those is a good step to take.

Also, with it being a 330i, I would check the DISA valves; make sure they still work, and also make sure that the plastic flap hasn't broke off. Those can restrict airflow and choke the engine if they get stuck or break off.

That's all I can think of off the top of my head, I also recommend checking for codes with BMW Standard Tools if you have that handy, and of course check the air filter and MAF sensor.

[rjahl]

Originally Posted by Fireball5657

In addition to what the poster above said, I recommend cleaning or replacing the VANOS solenoids and check valves. The original ones looked pretty good on my 328i, but cleaning them at only 98k improved my idle a lot and brought a little extra power back into the car. Since yours is at 200k, I'm sure it would make a much bigger difference, even more so if you replaced them.

I'm not sure replacing the injectors and fuel pump would make much of a difference. The fuel system is pretty robust on these N52s, the fuel system cleaner should be enough. Of course if I'm wrong, someone please correct me!

Replacing the coils and plugs will make a difference if they haven't been done in a while. OEM grade coils and plugs last about 80-100k miles before they start to noticeably wear out. Replacing those is a good step to take.

Also, with it being a 330i, I would check the DISA valves; make sure they still work, and also make sure that the plastic flap hasn't broke off. Those can restrict airflow and choke the engine if they get stuck or break off.

That's all I can think of off the top of my head, I also recommend checking for codes with BMW Standard Tools if you have that handy, and of course check the air filter and MAF sensor.

Please,
OP provided nearly no information, mileage, maintenance history, location, type of fuel he's running.

Could be just the summertime, it's hot and I'm running crappy fuel blues.

[Fireball5657]

Originally Posted by rjahl

Please,
OP provided nearly no information, mileage, maintenance history, location, type of fuel he's running.

Could be just the summertime, it's hot and I'm running crappy fuel blues.

I agree, that would be helpful information to provide, but I assumed that OP has taken all of those things into consideration before coming to the forums to ask for help. They opened their account in 2006, I'm sure they know how their car is supposed to act, and it sounds like they've been chasing this problem for a while now. Just trying to help in any way I can.

[whyzee125]

Clogged cats will cause a huge decrease in power while otherwise driving fine. Try going WOT in a single gear (say, 3rd) and see if it starts feeling more sluggish up high. Also do it with your windows down and see if you get a rotten egg type smell.

[crashoverride]

Originally Posted by whyzee125

Clogged cats will cause a huge decrease in power while otherwise driving fine. Try going WOT in a single gear (say, 3rd) and see if it starts feeling more sluggish up high. Also do it with your windows down and see if you get a rotten egg type smell.

You might be onto something... I had a similar problem at the last 100k mark and replaced cat once already