BMW Z3 2001 - Misfiring Engine ** Urgent Help*

[saadkhan]

Hi Guys,

My mechanic has changed everything relating to miss fires and it still wont fix the problem. My car is a BMW Z3 2001 2.2 (E36). Below work has been done and in the respective order as well:


1. Air flow meter changed
2. All 6 spark plugs changed
3. All 6 ignition coils changed
4. New head gasket installed
5. Engine flused and complete servicing done.


Once the engine was flushed the car was running fine for a few miles with no irregulaities. The mechanic told me to rev more than normal so that the new oil flows through completely. After about 10 miles the same problem appeared. When the car was idle on a traffic light it started miss firing and the engine light came on as well. The problem goes away if I switch off the car and switch it back on after a minute or two. I can see that I am not getting the same output from the engine which should probably be becasue of the miss fires.


My mechanic is inclined towards getting the ECU out and send that for repairing. All of the repairs up till now have cost me a fortune (£400) and sending the ECU for repair will be another couple of hundred pounds.


I am not sure, as the mechanic is going through hit and trial basis which is not working. I was wondering if someone has had the same problem. I am happy to hear any ideas that people think should help because at this point I do not trust my mechanic anymore.

Any help will be much appreciated.

Thanks,
Saad

 

[GazHyde]

Has the car been connected to a code reader at any stage by the mechanic? This really needs to be done first before randomly changing parts by trial and error!

 

[saadkhan]

Yes it has been many times. The code reader only tells about misfires in various cylinders. The misfires triggers many other codes not even relating to misfiring.

 

[GazHyde]

That's good, thanks for confirming. It's amazing how undervalued reading the codes is!

When it's miss firing what happens? Rough idling, back fire, stalling etc?

I've had rough idling when there was a split in one of the engine air intake hoses. My 2.2 is a little rough at the moment as it needs a cam sensor changing (I've done the inlet, not the outlet one).

 

[saadkhan]

On ignition the car runs perfect. When it is idle for a few minutes its to become rough idling. And when I continue it starts jerking giving a very rough ride. But as soon as I switch it off and leave it for a minute and switch it back on then the problem goes away. The car runs fine, I have taken it to Motorway and also taken it on high speed (above 80) and it runs fine. I saw that people were not able to accelarate when they had symptoms like this, but this is not the case with mine.

 

[Rev]

It hasn't been sat with the same petrol in the tank for ages has it? Petrol goes off after a while and can choke the engine when it doesn't burn properly.

I've read articles in classic car magasines and also now had experience of it. I struck a car up the other day and the thing sounded like a bag of nails and kept stalling. Had to keep it on choke and eventually when it was warm it stopped stalling. Topped up the tank and it got a little better, and then topped it up again and now it's fine.

It's been an issue for sometime but has got worse with the new legislation that so much of each gallon of petrol must be bio fuel.

Probably not, but always worth consideration. Lots of people have been calling out garages and running up large bills due to this issue.

 

[saadkhan]

The car is in regular use. I top up the tank every week as I use it for my commute to work. But no harm in trying. I will have a go at it in a couple of hours and let you know.

 

[Rev]

I suspect it won't be that then. I just thought you may have been getting it out of hibernation from over wintering.

But it does seem to have a fuel line ring to it. The way you said that once the engine was flushed it ran ok for a while.

I'm not up to speed with Z3's but does the fuel line have any filters? If so are they clear and ok?

Battery fully charged and ok? Sometimes if they're not charged with enough power available it has an effect. I've had management issues on a Z4 due to a tired battery. It wouldn't rev and was a bag of nails. Cleaned contacts and a charge put those lights out!

 

[Brian4]

Has it been plugged into BMW specific code readers as these give a lot more accurate diagnosis.

Air leaks into the inlet system, perished hoses. Blocked crankcase breathers. Lambda sensors regulating the fuelling 2 off.

Loads more before the ECU is suspect.

BMW readers are INPA or DIS

 

[zedonist]

Cam sensor triggers misfires, get it on a proper diagnostic

 

[t-tony]

My two penneth is inlet cam sensor as I had a very similar problem last summer. A simple code reader located my fault.

 

[Jamezee]

Lifters maybe.Before I bought my 2.2i the engine warning light was on, tried the plugs nothing, reader stated misfire cyl 3 . was ok for a bit then ran like a pig restart sometimes cured it. I took it back to where I bought it from and they had to send it to a indie to put all new lifters in. Really big job would have cost me thousands but the dealer stood the entire cost. Took a while to do it as well cos they had to strip the engine right down. Ran like a dream after though and has done ever since. he didnt make any money out of that sale! Maybe mention this to your mechanic or go to a good indie.

 

[oldcarman]

Change the fuel filter and get the pressure checked. Could be intank screen is getting clogged. Had that problem in my Volvo 940 turbo. Had to drop the tank, flush, put in new pump and filter. Problem solved. Jim

 

[zedonist]

If it was a mechanical or filter problem, the issue would be there every time you turned the car on, the OP states that switching the car off and on clears the problem, this points to something electrical, sensor or ECU. The car has not been on a diagnostic, as the mechanic has tried everything linked to misfires, all the expensive things anyway. I am sure that if you put it on a BMW diagnostic it will give you a code, cam, crank or other sensor, (fuel pressure, fuel injector etc as well as which cylinder the misfire was on. If there is no code recorded at all, then you know it is something outside of the normal use of the engine, cracked head, head gasket, intake leak, sludged engine etc.

For the sake of £30 - £60 I would get it diagnosed, or ask a member close by who has INPA to do it for you, you are probably just south of £1000 so far without resolution, it just makes sense