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Discussion Starter · #1 ·
You all are a great community, and I hope all your collective wisdom can help me make sense of this.

A bit of background.. I have an early 06 build date car, SMG with about 50k miles on the clock. No faults or error codes. Car clacked at idle from day one (noisy vanos, but not the loud buzzing that a few have complained about). No strange smells from the catalytic converters. Charcoal filters are sleeping in a box in my garage.

The car was fine when I got it a few months ago, but I noticed that the cars performance began to deteriorate.

It feels sluggish, and doesn't seem terribly eager to rev. When I first got it, 6-8k RPM in 4th gear was incredible, now it feels somewhat flat. In S6, if I floor it from a 5mph rolling start, it doesn't chirp the tires. On days when the car feels better, it might chirp going into 2nd (about 10% of the time). It never ever chirps into 3rd. Stock contis. I have a new clutch thats about 5k miles old.

Its almost as if the car is pulling timing. I've driven two other 06 M5s and they both rev more easily, feel stronger, and are peppier throughout the powerband.

So I tried some fuel cleaners in the gas tank for a tank or two. Nothing.

Had the sparkplugs replaced. Computer was telling me they were due in 4k miles, so I just had them done. I asked for the old plugs back and the color on them looked fine. The electrode was very noticeably oval, which should be normal with wear and the plug having 2 prongs.

A-ha! I thought. Surely this must be why! I've read posts about people swearing they got a good 20-30hp back just from swapping out worn plugs.

I drove the car ten miles. Felt about the same, if not a tad slower.

I'm running out of ideas. SHould I drive around a bit more and hope the ecu relearns after the plug change? My air filters are a bit on the dirty side - I don't imagine replacing these are going to have make a huge difference? Perhaps I need a new fuel pump and/or filter? Or is the vanos the culprit?

Any ideas??

thanks in advance!
 

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look in to testing your vanos pump, I am doing the same at the moment. I have a whistling noise sometimes under acceleration if I have the windows down. Your car should not be a lot slower with the vanos not functioning properly, the function of the vanos is to offer maximum power at any point of acceleration through its manipulation of timing. Hence, if you feel the car is creating a ******ation feeling it would likely be the vanos pump not functioning at optimum pressure levels.
 

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Could be a bad/dirty MAF. First try to clean them with some MAF cleaner. Remember this car has 2. so clean/replace them both and change the airfilters. Unplug the battery to reset the ecu, drive it hard for a couple days, i know a new MAF alone should get you power back. Just dont get the non oem MAF from ebay I hear they are hit or miss.

sidemarker
 

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I agree, clean the MAF's (theres should be instruction on here I believe so do a search. I'd use IPA (isopropanol, isopropyl alcohol aka rubbing alcohol or use electrical contact cleaner: but a type that doesn't leave a protective coating!))

Replace your airfilters, they are restrictive enough without dirt being present.

Replace the fuel filters also as these have been know to give problems.

Get the fault codes read and the fuel pumps checked (these also can give problems).

Lastly get someone who knows e60 m5's to do a dyno run and see if any ignition advance is being pulled plus this will give you a power figure that might compare (or not!) to other E60 M5's they have dyno'ed. I'd suggest RPI as prime and very knowledable people with the gear to help if they are near you?!

Regards

Jay
 

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Discussion Starter · #6 ·
thanks for all the feedback!! it's very helpful..

a few responses

1. the first thing I did when I got the car was to clean both MAFs with maf cleaner as well as the contacts on the connectors. Should I just replace the MAFs then?
2. no codes
3. i've read unplugging the battery causes all sorts of problems on this car?
 

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Have you actually put it on a dyno? I thought my car felt the same in P400 or P500 based on pure feel, to the point where I wondered if something was wrong. So I put it on a dyno and got the hard facts - it is healthy and making full power. Perception and reality can vary greatly.
 

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Discussion Starter · #8 ·
Have you actually put it on a dyno? I thought my car felt the same in P400 or P500 based on pure feel, to the point where I wondered if something was wrong. So I put it on a dyno and got the hard facts - it is healthy and making full power. Perception and reality can vary greatly.
thats a good point. I've driven a great many cars, and while not 100% accurate, i think my butt dyno is pretty good ;) .. if I had to guess, compared to the two other E60s i've driven, my car is probably down a good 50-70rwhp.

I think my next order of business would be to stop by RPI and do a dyno. Too bad they're not open nights and weekends.
 

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I think you will be doing the right thing. I'm sure RPI will be in the best position to let you know how healthy or not your car is. (then recomend a full GTS exhaust, headers, scoops, BMC filters, under drive pulleys, oil cooler, ESS tune and SC kit to get the power back up lol!) Just jesting!

Jay
 

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I agree a dyno will give you more substantial data. sometimes cleaning the MAFs will not do the trick. Once I got a new MAF on the x5 4.6is and after some driving adjustments the truck drove strong again!

sidemarker
 

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If you get a whining noise when you acceleration have you checked your fan clutch? That can cause a loss of HP, sluggish feeling and noise. Just throwing things out there to think about. Full on your fan and see if it is seized.
 

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If you get a whining noise when you acceleration have you checked your fan clutch? That can cause a loss of HP, sluggish feeling and noise. Just throwing things out there to think about. Full on your fan and see if it is seized.
We only have an electrical fan, not mechanical. Best of luck to OP and +1 on dyno
 

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Discussion Starter · #14 ·
Thanks for the response, M5Aud.. our paths have crossed on another thread and I'm thinking we may be on the same boat.

When I rev it in neutral, there is a faint whistling sound ... in the cabin with the windows up, winding out 3rd and 4th, i can hear a distinct whine. The car will pull ok once you get past 6k rpm, but everywhere else it just feels dead.

I do believe I will have the vanos inspected.

look in to testing your vanos pump, I am doing the same at the moment. I have a whistling noise sometimes under acceleration if I have the windows down. Your car should not be a lot slower with the vanos not functioning properly, the function of the vanos is to offer maximum power at any point of acceleration through its manipulation of timing. Hence, if you feel the car is creating a ******ation feeling it would likely be the vanos pump not functioning at optimum pressure levels.
 
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