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Discussion Starter #1
Hello fellow Bimmer fans.

So my '04 645Ci 6 Speed manual has been having problems for the past 3 months and I just can't seem to find the problem. And yes, I've browsed the forums for hours trying to find a solid answer.

So my problems are:

- The car won't start sometimes, usually after I drive it, turn it off and let it sit for a couple of hours. When I try to start it, all electronic accessories work fine but it won't even crank. Every time this has happened to me I will keep trying to start it and probably after the 30th time tuning the key it will start. Sometimes when I try to start it I can hear a click coming from the starter leading me to believe I have a sticking starter thats going bad but it happens so rarely that I don't think that could be it. The starter will click one probably 1 time out of the 30 key turns.

- The car will die on me! When I have my starting problems, after I finally get the thing to start it will die after about 15 seconds of idling. But thats not it! It will also die randomly when I'm at at stop and I start to move (not fully off the clutch yet), and no its not just me stalling. The engine will abnormally drop rpms and die. Also it has died on me while I'm driving normally like in 3rd gear doing 35mph but that has only happened once.

- The rpm gauge will jump all over the place and ill loose power. When this happens to me my engine will run really rough and sluggish and I can barely accelerate. When I do accelerate the engine shakes hard like it struggling to get moving.



Some other info to add is that Ive replaced my CRANKSHAFT sensor, that actually helped for about a month but now the problems seems worse. I also replaced me intake air box because my first one had a huge crack in it, with that I replaced my MAF sensor. Service engine soon light is on.

From the forums I've read some of the possibly thingS it COULD be are:
-Fuel pump
-Fuel injectors
- ISM(integrated supply module) or IVM, not sure if those two are the same
-DME
-Battery


If anyone could give some advice that would be great. Its my only car I have to get to work.
 

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First thing I'd do is start cheap and give the battery a good charge regardless, because it's a daily driver this shouldn't be too much of an issue unless your only a short distance from work.
Your DME shouldn't be a problem either unless you've had/have water in the DME box due to blocked drains, easy to check, just slot a piece of paper down the outside of the DME box itself and see if it's wet when you pull it back out, also you can undo the screws on the top cover and look to see if there are any tide marks in there indicating where a water level was sitting, if water has been in there you'll have to pull the modules for inspection/replacement if needed and clean up the wiring from any possible corrosion along with clearing the drains.
If you have the BMW software (DIS or ISTA) then run the codes to see if it gives you some insight and fixes/test plans for them, if not I'd order it asap as it's really useful with these cars and bonkers cheap now.
Because it's your daily driver and only car it needs to be sorted pretty quick so if you don't have the ability to run the codes then see if you can get to a garage/dealer during a lunch break to have them read but from what you're saying, while not ruling out electrical, I'd be airing more towards fueling so to start with I'd also get some top grade fuel in there along with some Techron to see if that helps first.
A smoke test could also be good to rule out any un-metered air but in the back of my mind I'm suspecting fuel pump from what you're describing yet I could be totally wrong there and unfortunately there's a lot to check out first before going straight to that.
If you do take it to a garage see if you can get them to check the fuel pressure at the rails as well.
 

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As stated start with a fully charged battery above 12 volts, or replace the battery if the age is unknown. The voltage must stay above 12 volts with the lights on & the engine off. Measure the voltage at the jump terminal under the hood, & charge the battery at the jump terminal. Try this & see what results you get.
 

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As stated start with a fully charged battery above 12 volts, or replace the battery if the age is unknown. The voltage must stay above 12 volts with the lights on & the engine off. Measure the voltage at the jump terminal under the hood, & charge the battery at the jump terminal. Try this & see what results you get.
My vote is for the IVM. Cheap and easy to replace.
 

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As stated start with a fully charged battery above 12 volts, or replace the battery if the age is unknown. The voltage must stay above 12 volts with the lights on & the engine off. Measure the voltage at the jump terminal under the hood, & charge the battery at the jump terminal. Try this & see what results you get.
My vote is for the IVM. Cheap and easy to replace.
Certainly can***8217;t rule it out at this stage and even if it isn***8217;t the problem it would be a good preventative maintenance change if it hasn***8217;t been done in the past.
 

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Discussion Starter #6
Thankyou for the input gentlemen. Ill start by checking my battery and Ill probably just buy a new one because my current one is old. Do you have any recommended batteries? And also did you guys do your battery registration your self or go to a shop?
 

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Not sure where you are located, but if in the US Pep Boys carry's the Bosch battery which has the best aftermarket warranty available. Look online & you can usually get a 25% coupon to get the battery down to 165.00 range. The Exide battery from the dealer is also very good, & can be negotiated down to around 220.00 if they are in the mood at the parts counter.
 

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IVM


Sent from my iPhone using Bimmerfest
 

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Discussion Starter #9
As stated start with a fully charged battery above 12 volts, or replace the battery if the age is unknown. The voltage must stay above 12 volts with the lights on & the engine off. Measure the voltage at the jump terminal under the hood, & charge the battery at the jump terminal. Try this & see what results you get.
I just checked my battery and all seems good.
 

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The IVM module would be next on my list. It will need to be purchased from the dealer, or an online BMW parts store. It cost around 125.00, & takes around 30 minutes or less to install. The module controls every sensor on the motor & tranny.
 
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