BMW M5 Forum and M6 Forums banner

1 - 20 of 20 Posts

·
Registered
Joined
·
1,548 Posts
Discussion Starter #1
Hey guys,
So i've been searching and can't seem to find the answer to my specific case..
i believe I'm suffering from a loss of power..
I have a 2002 M5 with 61,000 miles.
I used to have a check engine light for the cam position sensor bank 1 sensor A at 58,500 miles and I replaced that and the check engine light hasn't returned..
Before that the car was really low on power and would idle rough..
changing the sensor helped a bit and brought the car back to life with a smooth idle and the car had power again..
Yet still the car felt lacking..
I Changed the air filters and I cleaned the MAF's and this helped a bit and my car was a BEAST for about 2 days and then went back to being sluggish :/

I then replaced the MAF's the other day with new ones and then this helped a lot and brought the car really to life..
HOWEVER, occasionally the car will be somewhat sluggish and feel like I'm not at full power..
I have spark plugs and a fuel filter ready to put on the car tonight..
Do you guys honestly think that this might help my problem?
And if not what do you think it could be? Am I missing something obvious to check? I've replaced the oil twice since its at 58,500 miles and now its at 61,000 and I believe they are the original plugs..
I want my car back to being the full power beast it should be :flag:
 

·
Moderator
Joined
·
4,357 Posts
the different CPS sensors may be a cause - not 100% sure but ever since i did mine i've been paranoid that the 2 different sensors will come back to bite me


they are noticeably different so i dunno

either buy another one or see if a member with a matching set is willing to let you experiment

CPS sensors work independently of other engine components so if you have a shot engine it will not harm the CPS sensors
 

·
Registered
Joined
·
1,548 Posts
Discussion Starter #3
My engine is by no means shot..
I replaced the cps that was giving me a code and that was the last I've seen on my car on that issue..
I'm under the impression that I only need to replace the sensors when they go bad and/or are giving symptoms of a bad cps which is a rough idle and a massive hit on performance..
I don't believe its one of the cps sensors at this point.. I'm stumped
 

·
Moderator
Joined
·
4,357 Posts
My engine is by no means shot..
I replaced the cps that was giving me a code and that was the last I've seen on my car on that issue..
I'm under the impression that I only need to replace the sensors when they go bad and/or are giving symptoms of a bad cps which is a rough idle and a massive hit on performance..
I don't believe its one of the cps sensors at this point.. I'm stumped
:hihihi:

didn't mean to imply anything bad about your engine
- as i see it the sensors only read the empty slots at the back of the camshaft's pulse generator disk (butterfly wheels)
parts #2 & #4

 

·
Registered
Joined
·
1,548 Posts
Discussion Starter #6
I have the warranty but im in the process of dumping it the dealer is looking into it for me..
I like diagnosing my own car though so I know exactly what and why things happen so I'm not reliant on the dealer or warranties! Unless something gets real expensive lol
 

·
Registered
Joined
·
3,085 Posts
I had similar symptoms a couple months ago...my power loss was mostly low end torque. A 2nd gear pull from 20mph or so was very sluggish until it got high in the RPM's.

I replaced both intake camshaft position sensors and she's been all balls since. Not sure if it's the same issue but that's my 2c.
 

·
Registered
Joined
·
10,266 Posts
Cps sensors are hall sensors, magnetic pulse. I can only speak for my car but I have read this theme in other posts. When mine went bad it is not because of an electrical failure but rather a magnetic field fault. Maybe the magnetic pulse is weak or delayed. I can't tell you what is wrong because when I tested them they throw a pulse but they still throw a code. The second one that failed thru a intermittent code. Eventually it was a permanent code but still bench tested with a pulse. I would suggest they get weak until their signal sends info that the computer can test to be incorrect. Before the computer can figure out the info is wrong the info is still wrong, so your car does not run perfect.
I figured I should only replace them as I got a code,I was wrong. The week after I replaced the second intake CPS i replaced both exhaust CPS, just because so many have posted to replace all four when one goes bad, if original equip. I had more power , but now that the CPS system worked perfect. That lead to the computer deciding the VANOs solenoids were less than perfect and I got soft VANOS codes. Then I replaced the o rings and did a bit of soldering on the solenoids. I really had a lot more power then.

The original CPS are known to be weak and the new design is not. Eventually you will replace all four. If I was doing it again I would replace in pairs intake as a pair and then exhaust as a pair.
 

·
Registered
Joined
·
2,271 Posts
Stuff like that I would always do in pairs/full set, but that might just be me, I tend not to wait for fault codes :)

As per Sailor24's comment, I would do as he does.
 

·
Registered
Joined
·
1,760 Posts
It sounds like 3 more new CPS might be next on your list. If that doesn't fix it...

Plugs made a little difference for me but not a lot. Did you do change pre-cat O2 sensors yet? That made a big difference on mine. The old ones looked clean and were not throwing codes but 100 miles after changing my stuttering is gone, much smoother power delivery now. Trans fluid -> smoother changes and that helped too. I didn't have CPS issues so maybe this doesn't apply to yours.
 

·
Registered
Joined
·
798 Posts
Probably not your problem but I just did O2 sensors and saw night and day low end torque. 51k and no codes. Just did them as preventative and was very happy I did.
 

·
Registered
Joined
·
1,548 Posts
Discussion Starter #12
For u guys that changed ur pre cat 02 sensors and noticed a difference.. was your check engine light on?
 

·
Registered
Joined
·
1,760 Posts
No lights or codes for me. Of all the things I have done recently it made the most difference but I think I did not have the problem you are experiencing, just some hesitation here and there. But if they were on your list and you already had them it's a quick job to throw them in. Then do that fuel filter while you have the car up.

How many miles have you done since you changed the MAFs and CPS? It might take a while for the DME to adjust.
 

·
Registered
Joined
·
10,266 Posts
For u guys that changed ur pre cat 02 sensors and noticed a difference.. was your check engine light on?
This is a simple but not perfect way to check you O2s. You will have black exhaust pipes but if you put your finger in the black it should not transfer to yout finger. If it does then your O2s are weak, if you have ruled out other rich issues. If it does not transfer that unfortunately does not mean they are good. O2 are really only great to 50,000 km after that it is like turning 50 yourself, you are not dead but its a downhill slide.
 

·
Registered
Joined
·
1,548 Posts
Discussion Starter #15
Ok so everyone here agrees that at 61,000 miles I should change my pre cat O2 sensors and that should help regardless if I think there is a problem or not..
It feels like I'm throwing parts at a problem blindly but hey it would have had to be done later anyways..
Thanks guys
 

·
Registered
Joined
·
798 Posts
51,000 miles, no lights or codes. Just did them as maintenance. Made a huge difference. Very noticable in the low end torque.
 

·
Registered
Joined
·
1,548 Posts
Discussion Starter #17
Well I've got both pre cat O2 sensors on order usps priority lets see what all my parts can do for my car ;)
 

·
Registered
Joined
·
12,398 Posts
Cps sensors are hall sensors, magnetic pulse. I can only speak for my car but I have read this theme in other posts. When mine went bad it is not because of an electrical failure but rather a magnetic field fault. Maybe the magnetic pulse is weak or delayed. I can't tell you what is wrong because when I tested them they throw a pulse but they still throw a code. The second one that failed thru a intermittent code. Eventually it was a permanent code but still bench tested with a pulse. I would suggest they get weak until their signal sends info that the computer can test to be incorrect. Before the computer can figure out the info is wrong the info is still wrong, so your car does not run perfect.
I figured I should only replace them as I got a code,I was wrong. The week after I replaced the second intake CPS i replaced both exhaust CPS, just because so many have posted to replace all four when one goes bad, if original equip. I had more power , but now that the CPS system worked perfect. That lead to the computer deciding the VANOs solenoids were less than perfect and I got soft VANOS codes. Then I replaced the o rings and did a bit of soldering on the solenoids. I really had a lot more power then.

The original CPS are known to be weak and the new design is not. Eventually you will replace all four. If I was doing it again I would replace in pairs intake as a pair and then exhaust as a pair.

I used to subscribe to the "only replace CPS when they code bad"... but came to realize that these sensors can start getting 'sloppy' in terms of pulse sensing as they begin to fail.

+1 on this post....
 
1 - 20 of 20 Posts
Top