Today is not a good day.

[Zooropa]

Hi all,

I posted last week about my 1998 1.9 Z3.

Cut out a couple of times to and from work. Flat performance and using a lot of fuel then total loss of power, exhaust bang and black soot on tail pipes. I had code for Camshaft Position Sensor P0340.

Took it to a great garage who have been really helpful. Found a large air leak and repaired it. Unfortunately the hydrocarbons in the exhaust were still unacceptable.

Checked the Camshaft Position Sensor thoroughly and it was indeed broken. On hearing this I was delighted. New sensor was ordered.

New Sensor then fitted and values reset but unfortunately the car won't even start now

The mechanic I have been dealing with now thinks it is a problem with the timing and needs further examination to see whether it needs reset or a new chain etc.

Either way it's going to be expensive and necessary and unfortunately for me I am only two months after respray so I am in too deep to stop now.

If anyone has any thoughts I would be interested to hear.

Thanks

 

[Grumps]

Oh dear sorry to here of your bad luck. Like you say once your in your in. Check the MAF for further air leaks if that isn't what he has already found. Mine spilt and wouldn't tick over at all. Other possible on the 1.9 is the head gasket but I'm sure he will have checked that already. Hope You get it sorted.

 

[Zooropa]

Hi @Grumps

He has checked for any other air leaks and his result is 'discreet/zero' so he says that is practically nothing and air leaks wise we are fine now. Amazingly since the old cam sensor was pretty much dead, he believes that having no response from it caused the car to run on back up average values and therefore it would start. Now the new sensor is in it is being informed of a timing issue and therefore it can't start.

So annoying!

On the plus side, once sorted he expects a return of lost power and the car to stop using excess fuel so I may save a few pounds there in the long run.

Cheers

 

[Zooropa]

So it's possible the engine could have started with a timing issue when the sensor was dead and now doesn't start because the sensor is working and the brain now knows the timing is out? Am I understanding that right?

Also, any ideas on rough costs to reset the timing versus a new chain or other timing components?

Thanks again to all

 

[Tfp]

Faulty camshaft position sensor?

Every now and then a new sensor doesn't work, or possible a weak wire that's now broken when the sensor's been fitted?

I'd try another sensor before stripping out the timing chain.

 

[Zooropa]

@Tfp thanks for the reply. The camshaft sensor was replaced on Friday and was indeed at fault with the new one operating fine but now the car won't start.

Do you have any other ideas at all?

 

[Tfp]

@Tfp thanks for the reply. The camshaft sensor was replaced on Friday and was indeed at fault with the new one operating fine but now the car won't start.

Do you have any other ideas at all?

How do they know it's operating fine if the engine will no longer start?

First thing i'd do is refit the old one to see if it then starts.

Seems funny the engine will now not run when it did before the sensor was fitted.

Our cars are now quite old, it's not unheard of for the wiring to become a little brittle and can break when it's moved around to fit new bits.

 

[Faheem]

My old project had the same issue when I replaced the cam sensor. In fact, it had the same issue with two replacements. I swapped the sensor with an aftermarket, car didn't like it and just wouldn't start. As I've said previously, it's very difficult to find aftermarket camshaft sensors that work with the M44.

As @Tfp says, have them put the old one back in and see if the car will start.

Edit: I am making an assumption that the sensor you've fit is an aftermarket one. If it's OE the replacement sensor could still be faulty...

 

[Sean d]

What fault codes are been shown.

 

[Zooropa]

@Tfp @Faheem

It is a BMW sensor that has been fitted which gives me confidence. When the new one is unplugged completely the car will start as the old one was completely dead. There are no codes no being shown to my knowledge or certainly he never mentioned any today. Which wire do you mean may be damaged with the new sensor being fitted?

 

[Tfp]

@Tfp @Faheem

It is a BMW sensor that has been fitted which gives me confidence. When the new one is unplugged completely the car will start as the old one was completely dead. There are no codes no being shown to my knowledge or certainly he never mentioned any today. Which wire do you mean may be damaged with the new sensor being fitted?

Wont be a broken wire if unplugging the new sensor allows the car to start.

I'm at a loss I'm afraid, need to ask someone with experience.

 

[t-tony]

I think I would be looking at the crankshaft position sensor next, it could well be it is lying and fooling the ECU into thinking the timing is out. IF the chain had skipped it is most likely you would have suffered bent valves and if the engine runs with the cam sensor unplugged the valves can't be bent.

Tony.

 

[Zooropa]

@t-tony what is the function of the crankshaft sensor? Could that along with the cam sensor both failing have caused my original issues?

 

[t-tony]

Both the camshaft and the crankshaft sensors all send a signal to the ECU to say that the parts are in the correct position to fire the cylinder. If they don't all agree you get issues. The crank sensor on my 2000 2.0 Z3 was a pig to change right above the starter motor.

Tony.

 

[BMBabe]

Sounds like Some advice from #Zedshed is needed
@Lee

 

[Zooropa]

@t-tony thanks for that advice so far

 

[t-tony]

@t-tony thanks for that advice so far

Where are you located? I'm a bit confused by this "Found a large air leak and repaired it. Unfortunately the hydrocarbons in the exhaust were still unacceptable". Where was the air leak and how did they repair it? Why were they looking HC reading?

Tony.

 

[Zooropa]

Hi @t-tony sorry I'm just replying now.

The air leak was a breather I think. It was causing a significant vacuum leak so it was replaced.

The car was using a LOT of fuel prior to it stalling and backfiring etc and there was a rich smell from exhaust. They were checking if the hydrocarbons in the exhaust gases once the car had no vacuum leaks were within MoT pass range and they weren't so moved on to check sensor which was also dead so that was changed next.