2.0 (1990) facelift Sarting problem

[scratchbash]

Hi all,


Been enjoying the Z3 since begining of june, posting on here about various trips etc and using it as my daily runner. So far it has been utterly reliable.

However, this morning the starter turned over as usual, it started and ran for a brief second and stopped and has been reluctant to fire again.

Symptoms are: with ignition on there is a light buzzing noise from under the inlet manifold.This remains for about two secs after the ignition is off and the key removed. The motor spins very freely (it does spin its not the starter motor) There are no warning lights on the dash. There was a smell of unburnt fuel from the rear but I have stopped turning over now while I check out what is wrong.

If any of you guys have come across this before I would be grateful for some pointers.

Regards

Scratchbash

[geminimustang]

Should this read (2000)? Just a thought. The only problem we've had with the z3 starting has been a flat battery.

[Del]

As your battery is powering the starting motor ok and you can smell un-burnt fuel, I would guess that it is neither a fault with the battery or fuel delivery system. I would also guess that it is not an ignition coil or spark plug problem as you have six of each and it would be unlikely that more than one would suddenly fail – and the car would start & run rough on 5.

A large perish split in the rubber bellows downstream of the MAF sensor would weaken the fuel mixture so much it might well cause a non-start and these bellows are a well-known BMW fault area. If I had to guess at a sensor fault, the one normally put “in the frame” for a total inability to start, is the crankshaft position sensor. To pinpoint sensor faults you really need to plug the car into a fault code reader.

[scratchbash]

HI Del,

I agree, the one that usually lands in trouble is the Cam Pos sensor. I might have looked at these first if it had not been for the suddeness of the problem. I hear that both conditions you describe cause poor starting leading to failure whereas mine has only ever taken two turns on the starter to fire up and it did this yesterday.

Quite possibly I might have to get the codes read by my local call out!!

Thanks for the reply and guides.
Trevor

[Robert T]

Very quick test - unplug the MAF and see if it starts. Failed MAF can cause non-starting and without it, the engine will run with default settings. It may not be the MAF, but the simplicity of the test makes it worth checking.

Cheers R.

Sent from my Galaxy SII using Tapatalk 2

[scratchbash]

Thanks Rob,
I'll give that a go in the morning. At least it is easy enough to get to and as you say is definitive as a test for elimination.

Just as a aside, can the MAF fail catastrophically like this?

In the last few months I have noticed neither lack of acceleration or loss of economy!

Regards and thanks again
Trevor

[BladeRunner919]

It can, but do be aware that unplugging the MAF puts the engine into a default setting that will also accommodate other sensor failures, or air leaks etc.

[scratchbash]

HI All,

Well, a conclusion of sorts. I disconnected the MAF and gave it a churn on the key, it did not burst into life but after 5 -10 secs it sounded more promising than yesterday. So reasoning that without a null message from the MAF and still no start I might as well plug it back in! Two more 10 sec bursts on the key had the six limping into life whereupon it continued to idle roughly for a while before settling to a level idle. Took it for a short spin up to temp before switching off. then starting again, this time like usual, less than two/three spins before firing up again and idling like normal.

Recalling yesterday, I'm left withh the distinct impression that I had drowned the plugs somehow. Perhaps the combination of letting go of the ignition key before the motor is fully spun up and momentum has taken over sufficient for proper combustion to take place.

Either way, it is time to look at the codes my Z3 has stored up for me and to begin some of these preventative measures like getting a stock of sensors etc ready for the inevitable.

Thanks all for your input. Its great to know that there is a wealth of experience out there which can be drawn on, even over Christmas.
Regards
Trevor

[Del]

Are you happy that the plugs are in OK condition?

[colb]

I had similar problem on my 1.9 it set all sorts of codes and took me ages to trace the root cause, thought it was an air leak but failed to find one. Threw loads of sensors at it and finally changed the Maf for a new Bosch one, problem solved.
Always replace sensors with OEM parts ebay bargains in my experience are a waste of money.

Colb

[BladeRunner919]

Perhaps the combination of letting go of the ignition key before the motor is fully spun up and momentum has taken over sufficient for proper combustion to take place.

If this is what happened, then you definitely just flooded the engine. I got the impression from your original post that the engine started, then died rather than it didn't fully start, so didn't think to suggest this. All's well that ends well.

[scratchbash]

Hi Del/Bladerunner
Yes... there are a few items that possibly need sorting out/renewing, plugs will be the first.
I have given this car a good series of runs over the last 6 months as well as being the daily runner (it does 100 mi every day).
When I bought it, it was the previous owners periodic weekend car so it has seen quite a change of use. However, I firmly believe you get the best out of using a car frequently and by servicing it frequently too. Brakes, oil, water, exhaust etc have all benefitted from good use and run up to operating temp but I'm not so naive to assume that these will last forever. The brakes, after freeing off all the pads, now grip the whole disc and are just about to register completely on both sides!
This event, surprising as it was, has at least galvanised me into the idea of preventative measures rather than curing and at least armed with some of the sensors that are prone to failing, I can at least swap out to eliminate. Most usefulof all would be a code reader. Is there a specific one that best suits this car and my mechanical abilty (serious amateur)

Thanks all for your prompt responses, I never hesitate to reccomend this site when I meet fellow Zedsters.
Regards
Trevor

[colb]

Trevor
Have a look here for code reader & software http://bmtechnic.co.uk/bmw-diagnostic-cable/

You need a laptop to run this so its portable to plug in to your car, the INPA software is BMW specific, a lot of users on here use it.

Personally I already had code reader software that I used on my other vehicles before I got my Z3 and only needed the 20pin plug for the diagnostic socket although my car is also fitted with the 16pin obd2 connection as well. I upgraded the software I already had so I could view the Exhaust sensors. Quite happy with its performance and code reading and clearing capabilities.
My kit came from these people http://www.gendan.co.uk/
Its the Engine Check Pro version.

Have a look through the forum for other posts on diagnostics available, loads of info available.

Colb