Rough Idle And Poor Power On 1St Gear

[Asifur]

Hi guys,

I am new to this forum having purchased a E46 318i M/T of 2004 in Bangladesh last month.

I am in love with this car for her looks, but still unable to get the most out of her performance on the road, despite her having done around 14000 kms only. To start with, I found that the car was not retaining any coolant since water was being poured into the reservoir (common in Bangladesh where the drivers tend to pour water instead of coolant in good old Japanese Toyota, which does not give any trouble). Thankfully, this problem was sorted out when I bled her and poured in the proper coolant.

However, she had another problem with VERY rough idling, which gets worse when the air conditioner is turned on. Additionally, the car does not seem to have the power expected and acceleration is also very unsteady (especially on the 1st gear). There also seems to be a leak or some other problem in the exhaust since it is very loud and has that coughing tendency.

I am yet to visit a mechanic, but would appreciate any valuable feedback from owners who faced similar problems in the past or from anyone technical who has an idea what the problem may be.

I am a bit afraid that the car may not have been maintained properly in the past, but how much damage could have been done in just 14000kms?

Thanks a million chaps!

[Guest DazH]

Hello and a very warm welcome to the BMWOC

From what you have said, It may be one or a combination of a few different things.

1. First things first. a VERY good service! flush all the fluid and change ALL the filters!

2. If service does nothing (It needs it anyway) It may be worth looking for leaks. When it's ticking over, spray water on all the vacuum hoses

3. Clean out the throttle body. It may be getting stuck

4. Clean out the Idle control valve (ICV)

5. Run an OBD reader on the ECU, look for fault codes

ALL these, you can do yourself. Give them a go, then get right back to us!

Hope this helps,

Daz

[Asifur]

Thank you very much for your wishes and advice, Darren. I apologise for taking some time to acknowledge your post, because I wanted to let you know after spending some time on the car.

Finally, I had the chance to get the car serviced (change of oil and filters) and also check the throttle. We also checked the plugs and found they required replacement. However, the problem still persists after replacement of the plugs.

The mechanic is now saying that cylinders 1 & 3 are misfiring due to faulty ignition coils. We did not get a chance to check for fault codes since the OBD machine at the workshop was out of order. We will check for fault codes next week after the machine is repaired.

I can see that you have a very good idea about bmws and was wondering if you think that ignition coils may be the problem indeed.

Thanks again for your great assistance.

Regards / Asif

[Guest DazH]

Hello Asif,

Yes the ignition coils can indeed cause such problem but I'm interested in knowing how the mechanic has came to that conclusion of misfiring in Cyl 1 & 3 without an OBD reader. The coils are interchangeable so has he swapped them around and observed results?

Daz

[Asifur]

_{I think it's more of a hunch based on the performance of the vehicle than testing that led them to the conclusion. However, although they are fairly certain, they have also explained to me that they can only be 100% sure that the problem is the result misfiring cylinders and the number of cylinders after running the OBD reader.}

_{The parts will cost me a small fortune if I buy them from Bangladesh. If they are required, could you please advise me on the following:}

_{1. Do ALL ignitation coils need replacement or just the ONES that are misfiring?}

_{2. We replaced the old NGK 4-pole spark plugs with single pole BOSCH ones. Please advise if you think we should get a new set of 4-pole Bosch Spark Plugs?}

_{3. My sister lives in the UK and will be travelling here in a couple of weeks. I found the following website for ordering parts online and am thinking of asking her to collect the necessary parts from there. Please advise if you think the one below is any good or you have any other suggestions?}

_{http://www.sparepartstore24.co.uk/bmw-spares/3-saloon-e46/16198}

_{Sorry for all the questions and trouble, but your guidance is very useful for a first time owner like myself.}

_{Thanks again / Asif}

[Guest DazH]

Thats okay Asif, your request for help is very much welcome

1. Sometimes they all need replacing, sometimes they don't. On a 2004 vehicle, I would change the one(s) that are no longer functioning only.

2. There will be many different opinions related around this question as to some people, the spark plugs are more important than to other people. At the end of the day, a spark is a spark. The 4 "Pole" ones you are referring to are better but you will only notice the difference in a high performance engine which yours is not. But, for peace of mind they are cheap over here (Bosch Super4) so get your sister to bring some over for you.

3. Any UK based supplier will be cheaper than the guys over where you are. We use Ebay a lot as well as Eurocarparts. Shop around :)

HTH,

Daz

[Asifur]

Thank again, DAZ...

Yet to get tests done. Will certainly follow your suggestions for replacing faulty coils, plugs and shopping around. Will keep you posted on the test results and following replacement of the coils and plugs. Hope that should sort out the problems for now.

Take care and thanks a million - Asif.