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Jamesthefirst

2002 525i hesitation when pulling away...any ideas anyone?

43 posts in this topic

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

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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.

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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

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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!

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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 :wink:

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i should have included in my previous post that i took the hose off, blew through it and didnt hear any oil bubbling so if all is to be believed i have a split hose

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just to put this thread to bed now.....

After changing ccv and associated pipes, replaced a split blanking plug at the rear of the intake manifold, replaced o-ring around dipstick etc etc oil can now be heard bubbling when blowing through the top hose.

Also ever since i did that work i notced that when the car was stone cold if i pulled away then took my foot off the accelerator it would still move forward and just decrease speed steadily, before when i tried this the bloody car would near enough stand on its nose as if i had pressed the brakes so the car definetly benefitted from the new parts.

Only thing was i was still getting the occasional rev dropping and stalling when reversing so at the weekend there i pulled the idle control valve off, filled it with machine cleaner and thoroughly cleaned it, previously when it was off it seemed to move freely but actually this time after cleaning you can hear it clicking as you twist it and hey presto, it seems to have done the trick! Early days yet but im confident the car is at full health again.

Only one thing left to do now, when i turn a corner i can hear something rolling around behind the drivers seat i think. Iv had the carpet out, the door panel off and cant find nothing, also put a hoover nozzle up the heater vents under the seat but still no joy...any of you guys got an idea or had the same really annoying thing?

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Well....just to dig up this old thread, the hesitation thing never did go away after all and its really starting to bug me now. Seems to have gotten worse in the colder weather so i think tomorrow i shall pull everything apart and double check for any source of an air leak. Does anyone know what i could check on my bmw software package which would point towards an air leak in the intake pipework?

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I bought my car with the engine management light on, it had a rough idle and would also hesitate when moving off. I noticed a loud hissing sound from the engine bay which lead me to believe it would be a vacuum leak somewhere, hence why i bought it. I found that the rubber boot going into the throttle body has another pipe going off it had perished (i think it leads up to the idle control valve). But im guessing here - if you had that problem your car may have been alot worse and throw up countless errors linked with improper burn across your cylinders and dodgy lambda readings. but worth a shot anyway mate. mines a 2000 528i by the way m52tu

IMG_0334.jpg

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That wasn't too hard to diagnose eh! lol

I have previously checked all the pipework and changed the ccv, cleaned the idle control valve, ensured the DISA valve is tightly sealed etc etc. I even had the inlet manifold gasket changed. I think its a very slight air leak somewhere as it never flings a code, its not even a major prob but its now starting to annoy me.

Ideally i need someone with a bit of inpa knowledge to tell me what values i should be checking that would indicate a leak.....

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I've never had these readings checked (by anyone other than me that is, and i dont know what im looking for lol) but i will pop out just now and plug in the laptop then report back my findings. This morning i went out and stripped out the airbox and checked the hoses for perishing and splits, couldn't see anything wrong, and i've now put everything back together ensuring its properly sealed. Even sprayed highly flammable propellant around the whole inlet area to see if i could get the revs to rise but no, nothing.

Its either me being too hyper sensitive or its a fault elsewhere so i'll go and take a note of all the readings and post them up

cheers alpinaman

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Righto, i plugged in the laptop earlier today and took a look at the engines analogue readings.

engine @ 750rpm, about a minute after being started from stone cold, temp needle sitting just off the blue.

Total air consumption; 13.5kg/h

lambda probe before catalyst bank 1; 0.32V lambda probe after catalyst bank 1; 0.78V

lambda probe before catalyst bank 2; 0.73V lambda probe after catalyst bank 2; 0.72V

TV probe heating before kat bank 1; 99.31% TV probe heating before bank 2; 99.31%

TV probe heating after kat bank 1; 99.31% TV probe heating after kat bank 2; 99.31%

Does this seem normal for an M54 2.5?

Anything else i need to be checking the readings of on inpa?

Edited by jamesno1

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Your symptoms sound familiar to me (although mine is a V8). It was only a minor complaint, and for ages I couldn't figure it out and just lived with it. Then one day my airflow mass meter packed up big style. When I replaced it the difficulty pulling away was gone, it felt brilliant! I concluded that it must had been slightly off since I got the car, just not enough to flag an error.

It's not cheap enough to take a punt on, but if you've tried everything else it might be worth it.

dan mkii likes this

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Your symptoms sound familiar to me (although mine is a V8). It was only a minor complaint, and for ages I couldn't figure it out and just lived with it. Then one day my airflow mass meter packed up big style. When I replaced it the difficulty pulling away was gone, it felt brilliant! I concluded that it must had been slightly off since I got the car, just not enough to flag an error.

It's not cheap enough to take a punt on, but if you've tried everything else it might be worth it.

OP, you could try give it a clean rather then replace it, see if it helps?

http://www.powerenhancer.co.uk/product.php/225/bg-mass-air-flow-sensor-cleaner

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The other day when i pulled all the airbox and pipework out to re-check, I sprayed the MAF with electrical contact cleaner and very VERY gently used a cotton bud to ensure it was clean/dry. I was actually going to go to a scrapyard and buy one but they wanted £25 and to be honest it could be in the exact same state as mine so i didnt see the point in wasting the £25.

Looking at the figures i posted above, the pre-cat lambda sensor in bank 1 is different to the other 3 by a fair margin so i wonder if that may have something to do with it. This is the trouble with these things, i don't have any experience electrical fault finding so i don't know whether i'm pissing into the wind. And these days money is an issue so i can't afford to fling new parts at it willy nilly........ah the joys eh

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id strongly recommend taking the cdv out as mentioned earlier, i picked up a 525i 6 months ago and couldn't get a decent take off or a correct shift between 1st and 2nd i felt like a learner when taking off it was getting embarrising and annoying , it will cost you nothing to remove it just half an hour of you time the difference to me was like night and day http://www.zeckhausen.com/cdv.htm

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