LocostBuilders - powered by XMB

Any BMW technicians / experts on here

DarrenW - 28/7/08 at 02:43 PM

Having a strange fault on my 320D, already posting on BMWLand about it but no conclusive ideas coming forward. Just wondering if there was an expert on here i can consult with.

In summary the car is driving like its normally aspirated rather than turbo charged. It used to have an intermittent fault but since doing a major engine service at the weekend its now a permanent fault. No clunks, whistles, squeaks or rattles. No smoke. Everything seems perfect apart from no ooomph.

I have just,
Cleaned EGR and crankcase breather (car ran OK after doing these 2 jobs).
Oil and filter change.
Air filter and fuel filter.
Turbo pressure converter filter cleaned.
MAF cleaned (also tried unplugging but doesnt solve fault).
Inlet manifold removed, cleaned and deflapped (flaps breaking and being ingested by engine is a common fault on this model).

Ive tried swapping the EGR and Turbo PC's but no joy.

All i can think of is that i may have damaged some vacuum hoses under the inlet manifold that connect to 2 'valves' - no idea what these are for though. I have some replacement hose but taking manifold is a pain and a half. I have vacuum tested the turbo hoses and all seems well there.

Very strange indeed.

[Edited on 28/7/08 by DarrenW]

Mr Whippy - 28/7/08 at 02:59 PM

should have bought a

Krismc - 28/7/08 at 03:00 PM

Brother in law is a BMW TECH.... Ive txt him for you

graememk - 28/7/08 at 03:01 PM

DarrenW - 28/7/08 at 03:12 PM

quote:
Originally posted by Krismc
Brother in law is a BMW TECH.... Ive txt him for you

Thanks Kris. Appreciated.

Someone has posted on BMWLand to say it could be MAF sensor. Ive no experience of what faults these can cause. i was told if you unplug and power is back then it is faulty, however another reply contadicts this. Just trying the bits that dont cost first to eliminate as funds are tight.

britishtrident - 28/7/08 at 03:54 PM

Unplugging the MAF sensor is the normal test for a "naff" MAF if the performance dosen't improve it isn't the MAF.

The MAF sensor is a common fault on BMW diesels but it should revert to a fall back fuel map when you unplug it ---- the fall back fuel map is pretty good giving almost normal performance.

Cleaning seldom works --- shouldn't be done unless you know the sensor is out of spec because one touch can knacker the sensor.

DarrenW - 28/7/08 at 04:07 PM

Unplugging the MAF made no change at all so i guess it isnt that.

Im strongly suspecting ive damaged a vac hose under the inlet manifold but that is a lengthy job to take back off if changing the hoses then doesnt fix the problem.

It seems to be quite a complex engine, but also posibly used in Freelander TD4 and Rover 75 so solution might come from non BMW sources too.

Mark G - 28/7/08 at 06:59 PM

Have you tried having the fault memory checked. for the sake of Ł50 they may be able to tell you straight away what's wrong.

nasty-bob - 28/7/08 at 07:05 PM

I've got a 330d any had the exact same symptoms, and like some others have mentioned, it turned out to be the MAF sensor.

I beleive its a common problem.

Rob

britishtrident - 29/7/08 at 09:56 AM

What I forgot to add is that MAF faults seldom flag up a fault code --- that is why the test is to unplug.

If it were mine I would get a cheap fault ode reader and read the codes --- if it has the standard 16 pin EOBDC socket just about any obd/eobd reader will read the fault code.

Earlier BMW used a round socket.

Where is the engine ECU located ? -
On the Rover 75 Diesel which closely follows BMW practice there have been random problems with rain water flooding the engine ECU which is located behind the first half of the double bulkhead the cause is choked drainage ducts..

[Edited on 29/7/08 by britishtrident]

Rob Palin - 29/7/08 at 12:10 PM

quote:
Originally posted by nasty-bob
I've got a 330d any had the exact same symptoms, and like some others have mentioned, it turned out to be the MAF sensor.

I beleive its a common problem.

Rob

Yup, me too. Very sluggish 330D, cleaned MAF with carb cleaner and saw marginal improvement so replaced MAF and it was fine again.

DarrenW - 29/7/08 at 03:05 PM

Thanks for your replies. Ive tried everything bar the MAF so far (based on tackling lowest cost options first) and that is probs all that is left.
I even tried swapping the pressure converters over but im sure they are all working (easy to test on the EGR, EGR gets hot i fthe valve is pulled open letting exhaust gasses in).
Vacuum tested the vac hoses and they pull and hold good vacuum so that system should be OK.

Not really much else to try on the common fault list - hence suspecting the MAF now.

After removing the inlet manifold at weekend to clean it and remove the swirl flaps (common fault on my vintage 320D, flaps become detached, go into engine and ruin it), i had doubts that the vac hoses were OK. So today i got new hose and removed manifold again. Like a fool i forgot to take off dipstick upper bracket bolt, duly pulled dipstick out of sump and lost half of my fresh new synthetic long life oil!!!!! Oh how joyous i have been. Now trying to get an o-ring to back on the end of the tube - not fun. Of course the engine has loads of lower covers which are now full of oil. No doubt it will end up all over drive way!

DarrenW - 31/7/08 at 02:11 PM

Just to report back, im not sure if ive just reinstated the intermittent fault or cyred it but car is back to normal again. I replaced some suspect vacuum hoses.

Actually car is better than before after cleaning out the manifold, EGR and replacing filters.

Just dont forget if you are contemplatinmg a super service on your cars engines and the dipstick tube is attached to a part you intend to remove - undo the bolts first. i managed to pull the dipstick out and lose loads of fresh new fully synthetic oil In true BMW stylee the o-ring i needed was non-standard size and i had to order new one from BMW - luckily only Ł0.47 + VAT but 2 hours to fit.