Replaced glow plug control unit

[b20wht]

I have just replaced the glow plug control unit and I have gone from all glow plugs not working to just 5 and 6 not working ( so guessing they need replacing next) but I still have no glow plug light showing on dash with ignition on not even for a split second! Is this normal or is it because no. 5&6 are still not working or maybe another reason?

[X5Sport]

Normal unless it's about 5C or so.

Richard

[b20wht]

That's ok then. Does this mean that the plugs don't operate until it's belows 5c or just that the car doesn't really require heat?

[SMOKEY]

It's hard to find definitive info but I did read a post straight from a BMW technical document that said: glow plugs will have an active pre-combustion role when engine coolant is below 25 degrees. When engine coolant is below 30 degrees, it will also have a post-combustion role to help burn off emissions. Am guessing this is related to EGR.

My mechanic told me that they had a role to play at all times in ensuring clean combustion but I haven't read any evidence to support this.

My own conclusion is that if the car is starting up fine and not rough idling when cold - don't worry about it.


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[TimX5]

Mine shows up on diagnostics as all 6 not working, starts perfect every morning and it was bellow 5 last Sunday , puffs some smoke out when it's cold mornings  but in warmer weather it was fine , I'm a bit reluctant to changing the glow plugs and relay atm.

[b20wht]

Timx5 mine was the same, ran and started great ill all 6 not working even in he winter but I just wanted to eliminate the puff of smoke in the mornings.

Thanks for the help/info on this guys

[TimX5]

[quote="b20wht"]
Timx5 mine was the same, ran and started great ill all 6 not working even in he winter but I just wanted to eliminate the puff of smoke in the mornings.

Thanks for the help/info on this guys
[/quote]

Did it stop the smoke.

[b20wht]

I would say its slightly improved but i have today checked and I now have 1,5&6 glow plugs not working so it should improve when I replace these (not sure when that will be though)

[TimX5]

[quote="b20wht"]
I would say its slightly improved but i have today checked and I now have 1,5&6 glow plugs not working so it should improve when I replace these (not sure when that will be though)
[/quote]

I think when I get round to doing mine I'll  replace all 6 glow plugs and the control  unit at the same time.

[X5Sport]

Even with all six working on mine I still got a small puff of smoke in my E53 on cold mornings, and our E46 with the same engine is exactly the same.

Richard

[fenj66]

im not convinced that the puff of smoke on cold start up is down to the glow plugs. mine, with scanner showing 3 plugs down, always gives the puff summer or winter. my old 330d, now over 200k miles, still never puffs smoke and scanner says 5 plugs gone on that. it must be something else in the e53 engine design that causes it.

[X5Sport]

Could just be over fuelling for the start?  In which case it's gotta be pretty much guaranteed you'll get a puff.

Richard

[mashby]

My E53 has had 3 failed glow plugs for a year now, with no starting problems. It appears that engine ok with no glow plugs down to very low temps. Big job to change as need intake manifold off.

[Steamyrotter]

Small puff probably due to a leaky injector.

Mine used to do it until I got them returned.

As above, if it starts and you don't lose rear view then don't worry about it..