Performance reliability with mileage

[Jimstrim]

Hello everyone, I'm looking to buy a used e92 M3 soon and I'm wondering how long the performance will hold up as the miles climb. I've never owned an M car before, and I know the craftsmanship and quality is second to none, especially with the covered maintenance. But I still am weary of engine wear, piston clogging as I believe compression isn't checked during a service anymore (correct me if I'm wrong). My current car is a '10 Lexus RX350 with 100k and even with all scheduled maintenance and mostly highway miles, acceleration has taken a considerable hit from when it was new. I'm curious to know what mileage your current M3 is at, and if you've noticed any decrease in power (either observatory/dyno) or even better if you've had experience with lessening performance at a certain mileage mark. The reason I ask is because I'm looking to upgrade after I buy (exhaust, intake, ecu, race pipe, and exterior) and want to have an idea of how what mileage car to look for so I don't upgrade pointlessly. Thanks for all of your opinions!

[Z K]

Originally Posted by Jimstrim

Hello everyone, I'm looking to buy a used e92 M3 soon and I'm wondering how long the performance will hold up as the miles climb. I've never owned an M car before, and I know the craftsmanship and quality is second to none, especially with the covered maintenance. But I still am weary of engine wear, piston clogging as I believe compression isn't checked during a service anymore (correct me if I'm wrong). My current car is a '10 Lexus RX350 with 100k and even with all scheduled maintenance and mostly highway miles, acceleration has taken a considerable hit from when it was new. I'm curious to know what mileage your current M3 is at, and if you've noticed any decrease in power (either observatory/dyno) or even better if you've had experience with lessening performance at a certain mileage mark. The reason I ask is because I'm looking to upgrade after I buy (exhaust, intake, ecu, race pipe, and exterior) and want to have an idea of how what mileage car to look for so I don't upgrade pointlessly. Thanks for all of your opinions!

Well, The RX350 you have has direct injection. That causes a lot of problems with higher mileage if you don't do a top end cleaning that requires you to take apart the top end of the engine.

The M3 doesn't have any of that kind of problems. It uses port injection which is less fuel efficient. It is a gas guzzler with 12mpg city and 18mpg highway. The performance will not decrease over mileage. It uses a lot of gasoline that helps clean the intake ports and valves.

Read the forums. Besides a few people with engine problems from rod bearings, the M3 is a very reliable car. You should be able to get 100k+ miles out of it easily with no issues.

[Flying Ace]

Originally Posted by Z K

Well, The RX350 you have has direct injection. That causes a lot of problems with higher mileage if you don't do a top end cleaning that requires you to take apart the top end of the engine.

The M3 doesn't have any of that kind of problems. It uses port injection which is less fuel efficient. It is a gas guzzler with 12mpg city and 18mpg highway. The performance will not decrease over mileage. It uses a lot of gasoline that helps clean the intake ports and valves.

Read the forums. Besides a few people with engine problems from rod bearings, the M3 is a very reliable car. You should be able to get 100k+ miles out of it easily with no issues.

would this still be the case for the RX350 if he used top teir detergent gasoline throughout the entire life of the car?

[Z K]

Originally Posted by Flying Ace

would this still be the case for the RX350 if he used top teir detergent gasoline throughout the entire life of the car?

It doesn't make a difference. Direct injection squirts the fuel into the combustion chamber directly. You get increased fuel efficiency and power with this config as it is more precise than port injection.

The problem is, carbon builds up on the valves because the fuel used to wash the valves in port injection is not there anymore. Some newer direction injection engines have secondary injectors to clean the ports or change the engine cycle so it lessens the build up.

So fuel, running fuel injector cleaners etc won't help. You just need to open the engine head up and clean out the crud on the valves.

Here is what the carbon build up looks like on a 2010 GTI which has direct injection:

[phrozen06]

You have nothing to worry about. Just drive and keep up with the maintainance.

[Flying Ace]

argh! that sucks..same issue with the RS4's carbon build up due to the FSI:

http://en.wikipedia.org/wiki/Gasolin...tion#Drawbacks

I see what you're saying regarding gasoline no longer flowing through and touching the valves. Port injection FTW...for now, until the next generation FSI/GDI technology comes along!

[Jimstrim]

Originally Posted by Z K

Well, The RX350 you have has direct injection. That causes a lot of problems with higher mileage if you don't do a top end cleaning that requires you to take apart the top end of the engine.

The M3 doesn't have any of that kind of problems. It uses port injection which is less fuel efficient. It is a gas guzzler with 12mpg city and 18mpg highway. The performance will not decrease over mileage. It uses a lot of gasoline that helps clean the intake ports and valves.

Read the forums. Besides a few people with engine problems from rod bearings, the M3 is a very reliable car. You should be able to get 100k+ miles out of it easily with no issues.

Wow...thanks for the info, didn't realize it would make that much of a difference. That's a lot of gunk buildup! So theoretically, if the valves were cleaned, you would see performance restored?

And idk about it really being that much more fuel efficient, I'm only getting a combined 18mpg; much rather be driving a V8 at the cost of only 2-3mpg. Or I have a lead foot...