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Old 02-26-2017, 07:32 PM   #1
sweetbeats
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Running on 5 cylinders

Hey all...

My 2003 325xi is running on 5 cylinders...Reduced power, rough running...sounds like my Audi Coupe GT I used to have with the inline 5.

I can pull the ignition coil from each spark plug one at a time and each one makes it worse except for #3. I then swapped the #3 and #2 coils and there was no change so it's not the coil. I swapped the #3 and #2 spark plugs and there was no change so it's not the spark plug. Where do I go from here?
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Old 02-26-2017, 07:48 PM   #2
tritron
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Fuel injectors
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Old 02-26-2017, 08:07 PM   #3
sweetbeats
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How hard are they to swap to test?

The issue has been intermittent. Just got back from a long trip...thought I'd figured out the issue but it came back. At one point it went away when I had to do a sudden stop on the freeway. It's weird. And frustrating.

Last edited by sweetbeats; 02-26-2017 at 08:09 PM.
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Old 02-27-2017, 10:58 AM   #4
Landlorder
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You may need to do a compression test.
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Old 02-27-2017, 12:03 PM   #5
sweetbeats
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Yeah I could do that, but the problem has been intermittent. Up until this last week it would come and go, like instantaneously...one second it runs like sh!t and the next it runs like a champ. Now it just runs like sh!t. But I don't think it's a mechanical isssue (that would be revealed by a compression test). I believe it's ignition or fuel, but I do t know how to test the ignition system to ensure that the #3 coil is getting what it needs to fire that spark, nor do I know how to check/troubleshoot the injectors.

Any tutorials already on this forum?

This is my wife's daily driver, we just brought her grandma home to live with us to take care of her, we are broke, and I need to get the car running right again as soon as possible. I can't afford to take it to a shop. $$$

I was really hoping it was a bad coil but like I said I swapped #3 with #2 and there was no change so it's not the coil.

Last edited by sweetbeats; 02-27-2017 at 12:07 PM.
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Old 02-27-2017, 12:53 PM   #6
Landlorder
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Have you tried playing with the wiring harness for coil 3?

Hope its nothing mechanical. Usually not difficult to fix if it isn't.

Definitely try swapping injectors as well.

Also any codes other than the expected p0303?

Last edited by Landlorder; 02-27-2017 at 12:55 PM.
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Old 02-27-2017, 01:27 PM   #7
sweetbeats
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Unfortunately I don't have a code reader.

I haven't messed with the ignition wiring harness but I did notice the plastic wire guide for the harness wasn't seated on the valve cover and some of the tabs are busted...somebody has been in there at some point. We've only had the car for about a year and a half and don't have any history so I'm having to clean up some bad work on it. I'll open up the wire harness guide and look closer at the harness.

Is there any handy tutorials on swapping fuel injectors? Maybe I should just YouTube that and see what's out there.
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Old 02-27-2017, 02:00 PM   #8
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Quote:
Originally Posted by sweetbeats View Post
Hey all...

My 2003 325xi is running on 5 cylinders...Reduced power, rough running...sounds like my Audi Coupe GT I used to have with the inline 5.

I can pull the ignition coil from each spark plug one at a time and each one makes it worse except for #3. I then swapped the #3 and #2 coils and there was no change so it's not the coil. I swapped the #3 and #2 spark plugs and there was no change so it's not the spark plug. Where do I go from here?
First things first, with this much trouble you should have the Check Engine (SERVICE ENGINE SOON) Light on. Pull codes and see which cylinder is not working. The code should be P030n, where "n" will be 1 - 6. This will direct your diagnostic efforts to one cylinder.

You said that you don't have a code reader, my question is, why not? You have a car, you should have a code reader.

Go to eBay or Amazon and get an ELM-327 module. This will plug into the OBD II data port on your car, and in turn connect to your phone or tablet. Then, go the appropriate app store for your device and get an OBD II code reader app. OBD Fusion comes highly recommended, and Torque Pro is also pretty good. These are fee-based apps that you buy for about $5, there are free versions that you can take for a test drive. You could actually do pretty well with the free versions, but the fee-based ones will allow you to build and download log files about what the engine is doing. You can buy the module and the app for less than $30, certainly less than $40, and have lots of valuable information.
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Old 02-27-2017, 02:01 PM   #9
jdstrickland
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My instinct is that your next test is a compression test.
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Old 02-27-2017, 02:13 PM   #10
sweetbeats
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I will look at getting the ELM-327 module and app for iOS. Thanks.

Regarding the SES warning light that's the strange thing...it is not on. It comes on every now and then, but that was on my hit list because I assumed it was related to a need for a new catalytic converter and O2 sensor. But generally, even with the engine running terribly it is not lit.

Can somebody explain why a somoression test is suggested? If there was a mechanical failure (causing a loss of compression pressure), that wouldn't come and go. My problem comes and goes. I'm not trying to be argumentative...I just want to understand why a compression test is being advised.
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Old 02-27-2017, 02:20 PM   #11
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It is a requirement of the OBD II specification that the light come on with the key in Position II (RUN) before engine start, then go off after engine start. If the light does not come on, then you probably have trouble with the engine control unit -- computer. Of course, you could have a grounding issue. I wouldn't do the compression test until you can pull codes to understand what the car thinks is wrong with it. The car is screaming at you that something is wrong, you need to understand what it is telling you.
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Old 02-27-2017, 02:36 PM   #12
sweetbeats
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SES warning light comes on with warning light check when key is turned to position 1.
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Old 02-27-2017, 02:43 PM   #13
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Quote:
Originally Posted by sweetbeats View Post
SES warning light comes on with warning light check when key is turned to position 1.
Are you sure? It should not come on until the key gets to Position II (RUN). Position I is ON, this gives you some of the accessory circuits, radio for example, but not all circuits. If your SES light comes on in Position I, this is a fault. Having said that, it should remain on after engine start with the symptoms you are chasing.
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Old 02-27-2017, 02:47 PM   #14
sweetbeats
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My apologies. I meant Position 2. The SES warning indicator comes on at Position 2, and then stays lit after starting the engine for a couple seconds and then goes out. It only comes on occasionally while driving, but the majority of the time it is off...even when the engine is running rough.
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Old 02-27-2017, 03:19 PM   #15
jdstrickland
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Originally Posted by sweetbeats View Post
My apologies. I meant Position 2. The SES warning indicator comes on at Position 2, and then stays lit after starting the engine for a couple seconds and then goes out. It only comes on occasionally while driving, but the majority of the time it is off...even when the engine is running rough.


That's odd, the light is off while the engine is running poorly.

Have you pulled codes anyway? Of course not, you don't have a scan tool yet. Your local AutoZone/Advance Autoparts/Oreillys/Kragen might offer a free scan tool. You buy the tool, go home and scan the car, then bring the tool back for a full refund -- these stores frequently, depending on your state, offer a loaner tool program where you can use specialty tools for free. It works sorta like the library, except you buy the book (tool) and then bring it back and get a full refund.

The free loaner thing works good to get you started on working on your car, but owning the module and an app for your device is really the way to go. The module is your long term solution, the loaner plan is a stop-gap measure.
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Old 02-27-2017, 03:22 PM   #16
jdstrickland
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The ELM modules have a variety of price points that have mostly to do with being bluetooth or wifi or both. Get both if you find one. Your price point should be about $20 for the module. The apps cost less than $10.
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Old 02-28-2017, 01:27 AM   #17
TobyB
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Quote:
I can pull the ignition coil from each spark plug one at a time and each one makes it worse except for #3. I then swapped the #3 and #2 coils and there was no change so it's not the coil. I swapped the #3 and #2 spark plugs and there was no change so it's not the spark plug. Where do I go from here?
I'd second the fuel injector wiring, or ecu- the car can usually diagnose a bad coil. Intermittent like that makes it really unlikely to be anything non- electrical... and
that specific a cylinder makes it unlikely to be fuel pump, etc..
also, +1 on a BMW specific code reader- shadow codes can tell a lot.

hth,
t

Last edited by TobyB; 02-28-2017 at 01:28 AM.
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Old 02-28-2017, 06:33 AM   #18
Landlorder
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To swap injectors its pretty easy. You have to unplug the connector on the fuel pump or pull out fuel pump fuse. Run the engine till it dies. Remove positive battery lead on engine front. Release fuel pressure from valve on fuel rail with a cloth over the valve.

Remove injector wiring harness. Undo clips and pull out.

Remove screws on fuel rail. Pry off fuel rail from injector 1 working your way along. It can be twisted up to be out the way. Or you can release it from behind from the quick connect.

Pretty sure that's it from top of my head.
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Old 03-02-2017, 10:39 AM   #19
sweetbeats
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ELM-327 should be here Monday.

And just to confirm, yes the SES warning indicator lights at key position II, then goes out after a couple seconds when the engine is started and running...and yes still running like sh!t.

I checked continuity of all three pins of each coil connector to its respective termination point (i.e. the ground pins are all good to chassis, the wiring to the ECM is also good), so I'm reasonably certain it is not an ignition system issue unless it is ECM related.

So next step is to pull injectors, inspect, and check wiring continuity there. I'll do that tonight.

There really isn't a way for the home garage mechanic to test injectors is there? Like, if the wiring tests out, there won't really be any way I can be assured I'm not just pissing my money away if I go out and buy a new set of injectors? Right?

And if I do that and it still runs poorly then the ECM is suspect?

Thanks for all the help everybody...I really appreciate it.
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Old 03-02-2017, 10:51 AM   #20
Geo31
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Quote:
Originally Posted by sweetbeats View Post
ELM-327 should be here Monday.

And just to confirm, yes the SES warning indicator lights at key position II, then goes out after a couple seconds when the engine is started and running...and yes still running like sh!t.

I checked continuity of all three pins of each coil connector to its respective termination point (i.e. the ground pins are all good to chassis, the wiring to the ECM is also good), so I'm reasonably certain it is not an ignition system issue unless it is ECM related.

So next step is to pull injectors, inspect, and check wiring continuity there. I'll do that tonight.

There really isn't a way for the home garage mechanic to test injectors is there? Like, if the wiring tests out, there won't really be any way I can be assured I'm not just pissing my money away if I go out and buy a new set of injectors? Right?

And if I do that and it still runs poorly then the ECM is suspect?

Thanks for all the help everybody...I really appreciate it.
Get OBD Fusion once the ELM327 gets to you and you should know a LOT more.

The fact it started as intermittent makes me believe it is NOT a compression issue.

I'll throw in with the folks saying injector. Probably not a wiring issue, but crazy things happen, especially when it comes to electronics and German cars.

Also doubting the ECU/DME.
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