Performance drop - The Unofficial BMW M5 Messageboard (m5board.com)

cpatzer · 18th August 2007, 18:28

Okay, I am getty really agitated. Since I have purchased my ///M5 with 27k I have noticed a HUGE drop in performance. Only every once in a while does it perform as it used to. I now have 35k on the clock.

So far to rectify the situation I have replaced:

1) Plugs
2) MAFS
3) Fuel filter
4) Oil & filter (twice)

Ocasionally, especially after she has been driven really hard for an extended period of time does she perform like she should. I can almost never break the tires loose in a redline 2nd gear shift and I have to bring it to 4 or 5 k to break the wheels loose in 1st from stop. When it is hot out, I might as well be driving a Honda Accord.

Any ideas?

timisyourfriend · 18th August 2007, 19:48

air filters? dirty filters are killer. I know what you mean though, it's been like 100+ here lately, the car feels like crap. but on the plus side, last night when it was cold, i got my wheels to spin shifitng into 4th gear, not sure if thats common but i didnt think i had enough power.

m5 deamon · 18th August 2007, 20:36

maybe you 2 should consider the itas relocation kit. the e39 m5 suffers from heat soak

ard · 19th August 2007, 00:38

Quote:

Originally Posted by m5 deamon

maybe you 2 should consider the itas relocation kit. the e39 m5 suffers from heat soak

True, but when the air is hot it really doesn't matter WHERE you locate the IATS... hot air is hot air. Sure soak will exacerbate the matter, but summer driving is still a slower than it will be in the crisp fall air.

fluid · 19th August 2007, 03:29

Did you notice any difference after replacing the plugs & MAFs?

EM5PWR · 19th August 2007, 05:00

Quote:

Originally Posted by cpatzer

I can almost never break the tires loose in a redline 2nd gear shift and I have to bring it to 4 or 5 k to break the wheels loose in 1st from stop.
Any ideas?

Maybe it's the driver ???

alijonny · 19th August 2007, 07:25

sure you didnt buy a 528i with M badges? lol I just had to . sorry. i've just seen so many fakes lately.

KevinM · 19th August 2007, 07:57

Well, from reading posts on this board for 3 years, here are my thoughts on what affects E39 M5 performance without other symptoms (rough idle, etc.), some of which you have already addressed:

1. Pre-cat O2 sensors
2. Plugs
3. MAFS
4. Air filters
5. Altitude
6. Hot weather

Although I may be mistaken, CPS failures usually cause symptoms.

Other members have reported subjective power gains by replacing O2 sensors before any codes are thrown.

I must say, however, that your car seems at bit young for many of these things. At over 50K miles, I have replaced one O2 sensor (code, no performance issues) but am still using the other original O2 sensors, CPS, and MAFS. I am considering replacing them as a prophylactic measure, but have not done so as the car is running great.

How about altitude issues (as compared to where you picked up the car) or heat?

Mike S. · 19th August 2007, 16:50

What sort of fuel flow rates are you getting? Have you done the MAF test outlined in the FAQ?

As far as breaking the tires loose, what tires do you have, and what type of pavement are you driving on? It seems to me that some types of pavement lend themselves to wheel spin easier than others. Of course, I could be totally full of it. Wouldn't be the first time.

cpatzer · 20th August 2007, 18:32

Okay, well:

1) Don is a good friend of mine and I will be installing his IATS kit once he gets back into town (fingers crossed). I do think that heat soak has A LOT to do with it. When "cold" the beast seems to be, well a beast. Once hot or in the hot weather FUGETABOUTIT.

2) I usually run Chevron Supreme. I don't have any diagnostic equipment so I haven't run any tests yet. The MAFS were probably still good (waste of money) but at 30k why not.

3) Air filters aren't that bad actually.

Funny thing is every once in a while it decides to stand up on it's hind legs and roar. Especially after spirited driving. Other times, (most of the time) it just lays there and wimpers.

cpatzer · 20th August 2007, 18:36

Sorry, missed one of the questions. I am running Pilot Sports. I drive around Seattle. On saturday, I had been driving fairly agressively on 405, then I got caught in traffic. Once I saw an opening I gunned it, second gear lit them up just a little, like 1-2 seconds, then they grabbed.

When I first got the car it was colder out. Maybe I am just used to the cold air. I have been on a few group drives and havn't had any trouble keeping up, but man, when it wants to, it scares the crap out of me with it's speed. I want that all the time. I used to have to be careful of my gas input, now I just floor it all the time.

cpatzer · 20th August 2007, 18:37

Quote:

Originally Posted by fast4door

Maybe it's the driver ???

Not nice

Mike S. · 20th August 2007, 19:41

In my opinion, I think you should run the MAF test outlined in the FAQ, especially when it seems to be under performing, to see what the fuel flow rate is.

You don't need any special equipment to do this, the car does it for you.