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Discussion Starter #1
Hi guys

My m5 '01 can't reach any speed under 180-190 km/h.
When i accelerate, everything goes fine, i feel the full power under the bonnet, but when the speedometer is close to 180 or something like that, car dramaticaly looses all its power. And and there is no reaction on the throttle until speed slows down to 100. Than i can operate the throttle, byt wery softly and it is not very responding. Only switching ignition off and on solves this probleb and throttle became powerfull again.

the DIS test reflects nothing wrong with the car, no mystakes.

Any ideas? I am seek of "Capitan Slow" mode;(
 

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Sounds like limp mode/engine failsafe mode (however that usually throws codes) or maybe clutch slipping if power comes back as you slow down/start back up...tell us more.

Does engine speed as indicated on tach increase but car doesn't accelerate any more? What gear are you in? Cruising along or hard acceleration?

Explain more about exactly what happens when you say "engine looses all power." Does further pressing the accelerator bog down the motor and it stumbles and RPMs fall? Does motor ever stall? Or do you just have no power to accelerate, regardless of throttle position?

Trying to understand what's happening that's motor-related as I am not sure car speed (180km/hr) is the issue, but rather engine-related dynamics.

Could fuel starvation (filter/pump) or any host of sensors (e.g., MAFs, CPS, TPS) or even cat failure can throw you into limp mode but I've never heard of that without codes and/or CEL...surprised there are not for you if that's what it is. Do you have Peake code reader too?
 

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Well since you said turning the car off and on fixes the problem it leads me to believe it's not really a mechanical problem so much as it is a faulty speed sensor or something similar. Since you don't have any CEL's I doubt it's a limp mode problem, perhaps one of the two potentiometers on the motor or the throttle switch under the gas pedal are to blame?
 

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like ROUNDELM5 says, limp mode. engine goes in protection modus.
no codes too be found, and going in to limp mode = first thing too think about are the mafs.
when they start goin bad they dont always trow codes..thats why i suspect the mafs.
all the others will trow codes ,or the engine runs on several cilinders less..(cats, 02 sensors, cps sensors ,knock sensor, potentiometers, etc)..

try the l/h test on the cluster for maf readings.it schould be 130-140L at WOT in sec gear.
i bet your car doesn't get enough air data.


how old are the mafs on your car?
 

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Discussion Starter #5
Thank you all for trying to help.

1. The clutch works perfect.
2. Engine speed is relevant to car speed all time
3. on 6th gear
4. in hard, full throttle acceleration (was tried to reach max speed)
5. when i say "engine looses all power" i mean this: I drive on 6th speed on foll throttle. when car's speed comes to 180-190 km/h my acceleration stops. so it looks like I just ride on the gear without pushing gas pedal. so speed goes down and rpm goes down. but in reality gas pedal is on the flore. i can release it, i can push it again - no effect. and we have to take into account, that if I do the same on 1-3 gears - everything is OK. 4th and 5th I guess I've never tried before.

So... there are no error codes.
But I can believe this could be MAFs. I know that the problem with them often doesn't give any codes. And I have lossless air filters installed (with oil). I've heard this oil from filters can impact on MAFs. Maybe I need to try to clean them?
There is one more thing It could be MAFs. Full throttle acceleration is not strait. I can fell some "holes" in it.
And I have AC Schnitzer Control Unit installed. But it is done 100% according to the manual.


About MAFs... I've heard I can buy new for VW Golf - it has tha same part number, but for VW costs cheaper. Is it so?
 

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Thank you all for trying to help.

1. The clutch works perfect.
2. Engine speed is relevant to car speed all time
3. on 6th gear
4. in hard, full throttle acceleration (was tried to reach max speed)
5. when i say "engine looses all power" i mean this: I drive on 6th speed on foll throttle. when car's speed comes to 180-190 km/h my acceleration stops. so it looks like I just ride on the gear without pushing gas pedal. so speed goes down and rpm goes down. but in reality gas pedal is on the flore. i can release it, i can push it again - no effect. and we have to take into account, that if I do the same on 1-3 gears - everything is OK. 4th and 5th I guess I've never tried before.

So... there are no error codes.
But I can believe this could be MAFs. I know that the problem with them often doesn't give any codes. And I have lossless air filters installed (with oil). I've heard this oil from filters can impact on MAFs. Maybe I need to try to clean them?
There is one more thing It could be MAFs. Full throttle acceleration is not strait. I can fell some "holes" in it.
And I have AC Schnitzer Control Unit installed. But it is done 100% according to the manual.


About MAFs... I've heard I can buy new for VW Golf - it has tha same part number, but for VW costs cheaper. Is it so?
No you cannot buy the VW ones. They fit but they don't work correctly. The correct M5 ones are only $320 shipped from Bimmerzone so don't skimp. I see that you're overseas so you'd have to contact them to see what intn'l shipping would cost.

Yes you can try cleaning the MAFs and see if that solves the problem. It is a short term fix though so if you clean them and it fixes the issue, you need to replace your MAFs very soon. And don't run air filters that are oiled, it destroys your MAFs.

If cleaning/swapping the MAFs doesn't work, remove the AC Schnitzer control unit if you can (is that a chip?) to see if that fixes the problem. That probably should have been the first thing I would have done, but that's just me.
 

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here are some prices from germany for mafs..

the prices are great these days for mafs..:woowoo:

e39 m5 bosch Angebote - attraktive Preise für Auto Motorrad Teile, Serie Original Artikel bei eBay.de

you can clean your old mafs , but its a temporary fix though..once bad ,its only downhill..

the vw ones where cheaper a couple off years ago, but the cars ran too rich on fuel. what you saved on mafs you paid double over time in gas.

now that oem maf prices are dropped..not even worth it to buy vw one's, just buy the real deal and be good for a couple off years again.

and try to find some dry cone filters or go back too oem paper filters..until this day these perform still the best, and are cheap to replace.

good luck.
 

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Discussion Starter #8
Hi guys!

Have some update. On Sunday I've noticed my problem doesn't depend on speed. And this is absolutely logical, becouse of following:
for the engine falling to limp mode MAF sensor should lie one of the limits - high or low - of its sensetivity. So the speed can impact lowest limit, but I've driven in full throtle mode, so actualy it was highest limit of MAF in use... And this limit does not depends on speed, only on RPM of engine...

and I tried to make some hard acceleration on 3d gear. I've pushed the pedal to the flor till the highest rpm, then slow down and accelerate again. after three times I've cath the same problem but with "check engine" light. So I actualy think this are not MAFs, but may be sparks.
tomorrow I'll get some 100% workong MAFs from another M5 and try my experiment again.
And on the weekend will change the sparks. I didn't do it sins I've bought my car:)
 

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If you get check engine whats the code? If it happens on the third time and not the first two don't you think I could be fuel starvation? IE fuel not being transferred from one tank to the other, or weak fuel pump, plugged filter? Don't know just throwing out some food for thought.
 

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Discussion Starter #10
Hi everybody!
I have not checked the engine codes yet, but I've compared my car with another one in roll-on competition.
My competitor was M5 2000 with greater mileage, full stock, but 100% operative condition.
Conditions were: 3d gear, DSC on, Sport mode off, 70 km/h.
On my signal both of us puted the gas pedals to the floor. And my competitor has left me very very quick. Two times.

After this I tried to drive his car and I definately have felt much more power under my foot((
It is time to take care of my engine - sparks, coils, MAFs and whatever...
 

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Bosch PN is F 00C 2G2 029
 

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Discussion Starter #13 (Edited)

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Did you find out the reason for this?
I felt I had a similar thing happen to me today. Although briefly as I was just overtaking and was about to ease off, but while on full (or nearly full) throttle car stopped accelerating, it felt as though I'd lifted off completely. Once I had pulled back in, I accelerated and braked a few times and all seemed ok.
Didn't get any warning lights, I'm still waiting for my adapter to arrive to read any codes, so maybe that will give me a clue.
 

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Discussion Starter #17
Hi! I am back to the fast lane!;)
Decided to change everything to new and got started from MAFs. And you know what? MAFs replacing made the deal!)
I have my 400 horses again! All of them! I'm happy))))
 
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