42 replies to this topic

[jamesno1]

First post on here so be gentle folks

Car is a 2002 525i sport manual

Only had the car for a few weeks now but enjoying it very much (more than my previous e46 320i, e87 120d, e90 318i, e90 320i anyway) but there is a slight niggle and i dont know where to begin to fix it

When pulling away it seems very hard to get the revs right, either too much and the car lurches forward or too little and the revs drop to near stalling...its the same hot or cold i think. Also, to park up i have to reverse onto a slight incline and a few times i have stalled the car. At first i thought it was because i wasn't used to it but its definetly something not just quite right.

Now i have purchased ediabas/inpa or whatever the f#ck its called and plugged it in, car has no faults logged...well it did at first but i cleared them and they never came back (cylinder burn failure i reckon it said) so nothings is showing up. I have taken out the DISA valve (the flap on the side of the intake manifold) and all seems ok with that.

Anyway, do these symptoms ring a bell with any of you guys or is it a case of start from the start and replace all the usual suspects?

thanks for now

oh i forgot to mention.....if gently revving it to say 1500 or 2000 rpm it seems to vibrate around 1000-1100revs both on revving up and revving down (if u know what i mean), its hard to describe really, nothing that would cause alarm but it is noticeable and may be related so worth mentioning......

[michael.d.s.]

hi james welcome to the forum mate, the symptoms you have sound either like a ccv failure or an air leak, one way to find out if the ccv is at fault is to pull the dipstick out whilst the car is idling and if the idle stabilises and improves then the ccv is at fault otherwise it may be an air leak between the air flow meter and the inlet manifold. this article may help, there is a good chance I am totally wrong, someone may come along and correct me.

cheers

Michael

p.s. post pics of your car

[clipper]

My 2001 525i is exactly the same (I've had it a few months now) and I´ve previously had a 528i with a ccv problem and TBH it feels different. I've read in a few places that the M54 b25 isn't the torquiest motor BMW have ever produced, so just put it down to that. You soon get used to slipping the clutch "correctly".

Another possibility is the VANOS seal gone, but testing for that seems virtually impossible.

[jamesno1]

thanks for the info fella, actually the car idles fine its only when pulling away it seems jerky....do you reckon it could still be the ccv?

i havent got pics of the car yet, but once i finish refurbing the wheels and give it a good polishing il post some up

[DarkHorse]

@jamesno1, mine behaves exactly as you say, seems fragile below 1200rpm and is a pain to park or pull away sometimes compared to my other car (v6) requiring more throttle and revs to avoid feedback loop (may be Vanos operation at low oil pressure). I haven't looked for an air leak or check the CCV but there no fault codes yet.

Hope you investigate and come up with some answers if there are any to be had other than the 6cyl is weak on torque at low revs .

As for the 1100rpm vibration, again the same as I just noticed your reply in the E39 525i 2001, slighty uneven during engine over run (<2K) thread.

[alpinaman]

All these cars are manuals ??

Have any of you tried removing the clutch delay valve on the slave cylinder..?

Makes for a much smoother get away .

[clipper]

Interesting comment about the clutch, didn't even know this valve existed... but is this action masking an underlying engine problem ?

A few weeks ago I spent a good few hours reading this page and all it's forum links:

http://www.beisansys...s_procedure.htm

It's been posted on here before and I know a few have done the repair. What most catches my eye are these types of comments:

Symptoms



Cars experience:
Overall loss of torque and power, particularly in the lower RPM range, < 3k. Bogging then surging at 3k RPM. Uneven power distribution and RPM transition. Engine hesitations in the lower RPM range, < 3k. Louder idle and intermittent idle RPM hiccups. Difficult takeoffs. Loss of power and bogging when AC on. Increased fuel consumption.
Repairing the vanos seals provides:
Overall increase in torque and power, particularly in the lower RPM range, < 3k. Resolution of bogging then surging at 3k RPM. Smooth even distribution of power and RPM transition. Resolution of engine hesitations in the lower RPM range, < 3k. Quiet stable idle. Smooth easy takeoffs. Improved performance when AC on. Reduced fuel consumption, by ~10%.

Unfortunately the need to do this repair according to the parts manufacturer is unquestionable after as little as 20k miles, but that's hardly what I call impartial advice, it does look like a good guide though.

According to the forums (including this one IIRC) the failure rate may not be so high and many people who do the repair are simply acting on internet-forum-induced paranoia.....

Unless you've had your car from new and noticed a marked change in the power / torque characteristics it's very difficult to asses the need for spending so much money and time on this issue. My car suffers from most of the symptoms listed, except the loud idle and AC related problem, but I'm still not convinced that its not just that I'm missing the extra ccs going from a 2.8i to a 2.5i......

[DarkHorse]

> Have any of you tried removing the clutch delay valve on the slave cylinder..?
Not yet. I would expect the CDV (Clutch Delay Valve) to show up as an issue during fast clutch moves jumping up the gears or fast take offs lifting the clutch up quickly.

> Another possibility is the VANOS seal gone, but testing for that seems virtually impossible.
May be weak Vanos seals may be improved by using thicker more viscous oil (at the expence of some fuel economy). I might try this before the next oil change, thicken up the oil with a few cans of 'Wyns' or something to see what difference it makes (or not).

> but I'm still not convinced that its not just that I'm missing the extra ccs going from a 2.8i to a 2.5i
No I'm not imagining it either. When tickling the throttle and clutch the ECU does funny things . May be a characteristic of BMW striving for better fuel economy around idle rpm.

To add info, I once wrote (in thread E39 Manual gear box and clutch, picky observations.):
Also during pulling away from a standing start, seems that a combination between the Engine Management System (ECU sensory feedback loop couple with Vanos variable camshaft timing operation and age related latency) with a Duel Mass Fly Wheel clutch system (with a relatively narrow bite point) can cause a difficult to manage experience. Of course, when you first drive a manual E39 you think it's just that you need time to adjust to the heel hinge pivot throttle pedal characteristics... but it's not that.
The CDV (Clutch Delay Valve) would be contributory to a perceived variable bite point during quick gear changes as the clutch pressure plate is limited to close at a max rate restricted by the CDV fluid flow rate.

In summary I find I have to hit slightly higher revs (1500-2000rpm) before slipping the clutch in 1st to take off or be prepared to at extra throttle and 'gun it' if engaging at low revs (~800-1200rpm) where the power can quickly fall away under a small load. When slow maneuvering/parking I sometimes get the engine to start pulsing the revs 500-1200rpm and find a quick jab on the throttle sorts it out. Otherwise the engine is very easy to stall out from some sensory feedback loop (not sure but this may be an indication of another problem? ).


Adding a few extra revs isn't the end of the world but a fix would be nice .

[jamesno1]

what is the clutch delay valve or more specifically what function is it supposed to perform. I think there must be something wrong that causes the symptoms and its not just the 2.5's lack of torque because its not exactly a power starved car, it is still pretty powerful. Having owned a 320i in the past with the 2.2 engine even it didnt suffer this so i reckon it has to be something.....

me thinks its gonna be a case of changing things to see if it has an effect......

[valmiki]

I had the CDV removed on my prev E39, and if I'm perfectly honest I didn't notice any difference. Could've just been me though.

[DarkHorse]

> what is the clutch delay valve or more specifically what function is it supposed to perform.
It's a small hole that restricts the max flow of clutch fluid in the system, to help save the transmission from shock damage should your foot slip off the clutch pedal. Damping down the clutch action (that visually reminds me of those old 80s slow tape deck eject systems).

The problem when changing gear and lifting the clutch very quickly is that there will be a disconnect between 'where the pedal is' and 'where the clutch plate is in reality', a vague or delayed bite point. Which I don't think is the main problem here.

[alpinaman]

With the CDV still in place,it can feel a little unusual on set off if your used to setting the clutch normally..

As you say,there is a disparity between pedal and clutch plate position,this just makes the came seem weird on take off..

It was just a suggestion,and would cost £0.00 to try and resolve the issue,in my eyes its worth a try.

[brucey1]

I have had my 525i for nearly 3 years now and its had this problem from day one. I have to be incredibly smooth with the clutch to pull away smoothly if you go on the gas too early it kangaroos like a bugger. I have driven a couple of deisel e39s and never had a problem with their clutches.

[clipper]

May be weak Vanos seals may be improved by using thicker more viscous oil (at the expence of some fuel economy). I might try this before the next oil change, thicken up the oil with a few cans of 'Wyns' or something to see what difference it makes (or not).

I follow your thinking here, but given the pressue that VANOS works at, is it realistic to expect to notice any difference through thicker oil, this wouldn't actually increase oil pressure would it ?

I suppose it's worth a try because I'm relatively sure that this has nothing to do with CCV pproblems, in fact the only other fault on my car is an oil leak which I should fix first as this would probably negate any possible benefit of changing the oil. (I'm hoping it's the oil filter housing that's causing the leak, but I'm not yet sure).

[jamesno1]

Alpinaman....thank you for mentioning this clutch valve, i never knew it existed and it certainly makes sense now how the car feels different to others....

I'm not sure this would be the cause of the revs dropping though when pulling away. I'll tell you something else i notice...there is a sound of air either being sucked or expelled near the DISA valve which seems quite loud but i cannot pinpoint where from and i cannot find any hoses nearby which are bust. Is this normal, you guys have the same?

[alpinaman]

Have you had the CCV valve checked ??

Any easy check is to run the car at idle and remove the oil filler cap. Put your hand over the oil filler hole and see if you feel any vacuum.
A badly spilt CCV will suck the palm of your hand onto the oil filler hole.

Also a split CCV would give a long term fuel trim fault under diagnosis..

Worth a try!!

[jamesno1]

i put a thin plastic bag over the oil filler hole and it did suck that in maybe half an inch or so. The ccv is a pain in the arse to get to isnt it? Is it the valve itself that gets knackered or the pipes attached to it that split? I may just order up the parts, strip and swap them if this is the likely cause of my woes.....

Anyone have part numbers or typical prices for the ccv and hoses?

[Shires]

A few weeks ago I spent a good few hours reading this page and all it's forum links:

http://www.beisansys...s_procedure.htm
...
My car suffers from most of the symptoms listed, except the loud idle and AC related problem, but I'm still not convinced that its not just that I'm missing the extra ccs going from a 2.8i to a 2.5i......

I changed the VANOS seals on my car. I found it easy to diagnose with a manual box. Mine was a changed car afterwords, much more enjoyable to drive. If the VANOS seals fail on all of the 6 cylinder petrols, then I can understand why many people say the 520i is underpowered. Here's what I wrote on another forum:

here are the symptoms I had with failed VANOS seals. I didn't have any noise from the VANOS unit so mechanically it was OK, just shrunken seals on the VANOS pistons.

1) Stalling when taking off from the lights, revs needed.

2) Utterly gutless below 3000 RPM. I think the VANOS is by default in the failsafe position, so you get power at high revs for overtaking even if it's not working.

3) VANOS sometimes taking an age to adjust, e.g. floor it and wait.

4) Occasionally VANOS never adjusting - e.g. floor it in 3rd at 2000RPM and nothing happens.

5) Doing a full throttle takeoff in 1st gear, would get a big surge in power around 3000RPM pushing me back into the seat as the knackered VANOS kicked in yo!

Replacing the seals has made a huge difference. Instant throttle response and it never fails to pull above 1500RPM. It's quite nice because I can leave it in 3rd gear for pootling around town; couldn't do that before as the car just wouldn't accelerate from low RPMs.

EDIT: I got the seal kit from here: http://www.beisansystems.com/

Corresponded with him a bit, he's a very nice guy and although the kit was $60 it was well worth it.

[jamesno1]

£60 for a couple of rubber o-rings is fucking scandalous if you ask me. I hope the vanos isnt away in my (genuine) 73000 mile car as i will baulk at shelling out that kind of money for so little.

Actually, does anyone have the dimensions of the o-rings on here, maybe try sourcing them at a more realistic price?

[Shires]

£60 for a couple of rubber o-rings is f*****g scandalous if you ask me. I hope the vanos isnt away in my (genuine) 73000 mile car as i will baulk at shelling out that kind of money for so little.

Actually, does anyone have the dimensions of the o-rings on here, maybe try sourcing them at a more realistic price?

60 dollars, so about 40 quid, that gets you 6 O-rings, 4 teflon rings and free tech support. I guess he can charge that because he knows the dimensions and where to get them made.

[jamesno1]

aye you've hit that right on the head there, although i'm surprised no-one on here has bought some, measured them up and found a supplier already....hmm maybe a wee sideline for me.

I've read up a wee bit about the vanos thing (as you do when buying older cars), there doesnt seem to be a test to determine if it is indeed fucked. Is it possible to disconnect the wiring to it and see if it doesnt get any worse (then you know its broke) or if it then gets worse you know yours is ok? Has anyone else tried this or am i being stupid?

in fact maybe dont answer that

[jamesno1]

fnuk fnard????? oh, i see, it changes the sweary words for you .......ha ha ha

[Dan.]

fnuk fnard????? oh, i see, it changes the sweary words for you .......ha ha ha

You can turn off swear filter in your control panel, I saw what you put first time

[jamesno1]

ha! clever forum eh....iv changed it now.

Anyways...does anyone know if disconnecting the wirring to the vanos could identify a problem with it or not (is there a wiring connector to the vanos?)

[Shires]

ha! clever forum eh....iv changed it now.

Anyways...does anyone know if disconnecting the wirring to the vanos could identify a problem with it or not (is there a wiring connector to the vanos?)

Depending on your engine there are one or two solenoids controlling oil flow to the intake (and exhaust if two) VANOS pistons.. You can pull the connectors at the solenoids and drive like that but I'm not sure what it would prove.. rpg530 on here said that it helped him to diagnose that his seals were shot, but his VANOS seals symptoms were a bit different - stumbling idle etc if I remember. I never tried that on my car, knew they were shot because my 1.2 8v Punto pulled better at low revs.

[jamesno1]

hmm dont suppose it could do much damage to just try it then and see what happens. think i'll try this over the weekend

[clipper]

Sounds reasonable enough. If unplugging the solenoids disables the VANOS but there's no noticeble difference in performance it would be logical to assume that the VANOS aren't working when "enabled".

Please let us know what happens with you test Jamesno1.

[jamesno1]

aye i will do fella.....

and maybe by that time i'll be finished refurbing the wheels, get my two new fat bridgestones on the rears and get some photos taken.....

hope its dry this weekend

[stevros]

ive noticed just the rev drop when first pulling away on my 530i 51 plate. its only when first moving away never when then accel or anything in any gears!?! does mine have single or double vanos units? what engine (code) is mine? i'm new to the forum and bm's! (this is my first) i may replace the vanos seals just incase i think. thanks guys!

[jamesno1]

I've read somewhere that by taking the top hose off from the corner of the valve cover and blowing through it i should hear oil bubbling. If you can't apparently it means a hose is split somewhere in the ccv pipework. Before i go ordering up new hoses and ccv is there anyone on here who has replaced theirs who could confirm if what i've read is true?

Not that i dont believe everything i read on forums but.........yeah second opinions from people who've done it woiuld be good