engine question

[micklaw]

hi all
was looking for a bit of advice on the engine.
when ticking over it seems to be slightly lumpy
( like it is missing )
any ideas
thanks micki have a 1.8 so its says on the boot lid

[XVar]

The first thing to check would be for splits on the hose between the air intake and the throttle body, this was the cause of my dodgy idle and replacing the hose made a huge difference. Another possibility is the ICV (Idle Control Valve), if you use the forum search you should be able to find some of the previous threads about it.

[Del]

When does this occur? On the first cold start of the day, only when warmed up or all the time? What happens to the revs, are they very erratic?

[micklaw]

hi guys thanks for the response
it happens when the engine is at normal temp (temp gauge in middle hot/cold)
it seems to tick over fine then the revs dip only for a fraction of a second and then come back to normal
its does not effect the running when driving.its just one of those anoying things i want to get right
thanks mick

[Del]

It sounds quite slight and could be a lot of things. The coil pack on the 4 cylinder engines is away from the engine and so would not be affected by engine heat in the same way as individual coils above each plug – my guess therefore is that it is not the coil pack. I’ve also been told that the original Bremi HT plug leads are generally considered “bullet proof” and so I would tend not to initially suspect those either.

If it were me, I would focus on the possibly that a spark plug is worn or breaking down internally. I would also focus on the rubber MAF boot as recommended by Xvar – all Z3s are now at least 10-years old and at the very least these rubber items will have started to harden before they perish and split. You could have a small air leak there. Thirdly, on an older vehicle (which all Z3s now are) I would consider carefully cleaning the MAF sensor itself with an appropriate cleaner e.g. Halfords electrical contact spray cleaner.

[jont]

Hi
I have a 1.9 and have had the same sort of problem when idling first thing in the morning,have a look at the idle control valve take of and clean the throttle unit inside.

The other thing you can do and i would fully recomend a peake engine engine error locator i have just bought and they are brilliant
R5/FCX3 - Peake Research R5/FCX 3 BMW Engine Scan Reset Tool (1987-2000) sales@eurosportdesign.com.

Regards Johnt

[micklaw]

many thanks del will have a look into all your soloutionsand try them out
thanks again

[micklaw]

hi just read about cleaning thr maf sensor in the forum .
can it cause as many problems as it says or is it just a simple take out and clean job.

[Del]

MAF cleaning - need to be careful as it is an expensive/delicate sensor - see link attached viewtopic.php?t=24621&highlight=maf+cleaning

[mrwhippy]

I would certainly agree with checking the spark plugs.

My 3.0i Z3 has just spent 2 days in BMW with them trying to find the cause of my intermittant lumpy running and exhaust emissions warning light. Luckily this was under warranty as the Nissan dealer from whom I recently bought the car could not find the fault.

I got the car back on Thursday afternoon, fitted with a new set of spark plugs. No other work was carried out. The car is running great and with no emissions warning light.