Rough idle with white smoke

[Fletcher1984]

Hi everyone Ive recently bought a 2006 x5 it's got 84000 on clock full service history but in the morning on start up it idles really bad it like makes a rumbling effect inside car and smokes for about 1 min until warm I had new glow plugs n relay changed fuel filter n had injectors tested two come back faulty so changed them two only the ones that we're faulty tho but the car drives like new afterwards it's going IN next week for cool temp sensors n exterior sensor n another service along with gearbox oil Change any help would be highly appreciated thankyou

[X5Sport]

Could be the MAF is going faulty.

Worth getting the fault codes read to see what else might be showing up.

[Fletcher1984]

I took it to bmw n they said that they think it's injectors but I've had them tested the head technician at sytner said it had him stumped do u think it's worth getting the mad sensor changed ? Thankyou for your reply

[X5Sport]

Another BMW garage unable to fault find because the computer says it's all OK eh?  Hmmm.

See what other folks on here come up with before jumping in and changing things.  There are a few areas it could be that also need considering.

[Fletcher1984]

Ye that's the second time they had it and couldn't tell me what's up they said they thought it could be injectors but I had them tested . They had 8 days last time round n cost me £620 n was no different I am open to any suggestions do u think getting sum maf senor cleaner n try that ? N thanx again

[ianst0028]

i've tried the maf cleaner before and tbh it makes no difference
you could try running it without the maf and see if it gets rid of the white smoke/rough idle that might help confirm if its that causing it ..... but dont forget that youll have a whole new set of warnings flash up when the maf is unplugged

[Fletcher1984]

I'll try that in a minute thankyou do u recommend anything else if it doesn't work?

[toonarmy]

I used to get smoke on heavy accelaration blanked the egr off and cleaned Maf all good now

[X5-D-Sport]

Specifically... white smoke is Uncombusted diesel OR water vapour from startup.
Experience says... that just bevause it goes to a main dealer, does not mean they think oitside of the box..

rough start up is typically one or several of the following..

*heater plugs failed or failing... due to not getting power or failing items
*mucky injectors not giving a clean burn until the combustion temperatures get hotter
*water in the fuel
*electrical connection issues

the lumpy start-up running hints at a failed glo plug and/or a dirty injector.

if they charged you £600 & failed to solve the issue... then I would be asking for some refund on labour...
because.. if they knew anything, they would have solved the issue by now !!!

Returning to these idiots is just hoing to waste your money, because if they vouldnt find the issue before, they will just repeat and bill you yet again for sod-all.

it could even simply be a poor electrical connection to a glow plug or injector...
the diagnostics will say all is ok, because micro-amps are drawn to test the electrical continuety...
however....
when the parts are properly operating, they are VERY power hungry & only then will a poor connection be apparent....

the garage arse-holes should know this but often are blinkered by diagnostic tech equipment than seeing the real world.

my 1st route would be a can of electical contact cleaner from Maplin, then a root arount each and every connector on top of the engine... pull each connector in turn, examine inside for slop or rust, then a BIG squit of cleaner in each half, and many plug/unplug ops to ensure a good firm connection, then move on to the next one.

once done, track back down the loom to the main connector before the branch offs, and do the same again.

before you do any of this...
with a cold engine, you could disconnect an injector and matching piston heater plug in turn... start the engine & see if it effects the running... when you get to the one that makes no difference, then you have narrowed it down to the specific injector or glow plug...
may take a couple of cold starts to work your way thru them...
but at least ot wont cost another £600 to achieve sod-all & then you specifically know where the fault is....
then you do the start up be negating either the plug or injector to narrow down to the specific item.

just means you may have a few cold start days with the engine cover off for quick access.

Enjoy.

Grant B

[Fletcher1984]

Thankyou grant I will defo try what you said and thankyou for the reply