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Discussion Starter · #1 ·
hi everyone,
I bought a 318ci 2lt 4 cylinder 2003 post facelift about a year ago.
I have had many problems with it since but i ( and my mechanic) have always been able to sort it out with the exception of one long standing issue which neither me, or my mechanic have been able to pin point. I am hesitant to take it in to the main dealer as there diagnoses costs are extreme to be mild.

I am hoping that someone with some more mechanical experience and first hand BMW knowledge might be able to help me diagnose it.

the symptoms are as follows and are not necessarily linked.

Poor power at low revs, increasing over 3000 revs.

un-even acceleration through gear range. especially 2nd and 3rd. although a suspect this just because of torc ratio.

Reduced power generally over time.

occasional battery light flashing once ( this is maybe one or twice per week and has no obvious common cause).

occasional "hunting" on take off from junctions. ( for example, i will slow down and stop at a junction, when i turn right ( almost aways turning right) the power will die and the engine will "hunt" for maybe 10 seconds and i will have to limp onto the road. then the power will return and i can continue as normal.

engine / exhaust very throaty. verging on asthmatic on occasion.

There are no fault codes,


here is what i have tried,

I have replaced the plugs ( but not the HT leads )

I have replaces the MAF, twice. and repaired the loom connection as there was a loose wire causing a "non signal return' to the engine management computer.

i have repaired a leak in the air intake system. ( there was a small hole in one of the vacuum tubes which mechanic repaired with epoxy resin.

The car has done almost 150,000 miles

this problem has been persisting for nearly a year.

If there is a BM genius out there, please help me
Robbie.
 

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BMW never sold any 4-cylinder (or diesel) models here in the US, so those models are like UFOs to us....I would start out by checking the basics....fuel pressure at the fuel rail check valve, etc. Was the fuel filter ever changed ? They get pretty nasty after a few years, often causing problems....

Good luck ! :thumbup:
 

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Your mileage suggests checking out the cat to make sure its not physically restricting flow which it can do randomly as it breaks down and jossels the not any more monolithic debris around .. happens earlier for some cars & later with others.
 

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Discussion Starter · #5 ·
Thanks for your advice guys,

I got a new post cat back pipe recently. i am presuming the tech that did the exhaust would check the cat whilst he is doing the job.

i had the codes read and that is why i replaced the MAF twice and the signal return replaced. we read the codes after and there was nothing. that is why it is so perplexing. :)

I will check the fuel filter. as far as i am aware it has NEVER been replaced so i am going to look into it. Thanks. :)

is checking the fuel pressure at the fuel rail check valve difficult or require special equipment? should i take it to my mech or is it doable by myself?
:)
 

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Remember that the codes provide you with symptoms and not solutions! Hence, you replaced a probably good MAF with new ones.

Checking the fuel pressure at the fuel rail is easy. You'll need a pressure gauge that can connect to the Schrader valve on the fuel rail.


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