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Hey, my 08 e90 petrol is showing the engine light and driving rough and low power but if i switch it off and lock it then put it back on it drives fine and the engine light goes. Any ideas fellas?
 

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Get the engine codes scanned and it will tell you exactly what's wrong
I did, its not consistent so theirs no codes showing, I am thinking it could be dodgy coil, would anyone who is familiar with this think thats a reasonable conclusion?
 

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No, swapping parts at random with no diagnosis is not a reasonable conclusion. Pull the codes.
If the check engine light is on, and your scanner pulls no codes, you're using the wrong scanner. Use a scanner that can read BMW codes. A generic OBD scanner is not suitable.
 

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If it's a bad coil you should be able to kick the light on by revving the engine high up.

Sent from my SAMSUNG-SM-G900A using Bimmerfest mobile app
I will give this a try, I am in Ireland where mechanics charge mad amounts just to plug the car in and they end up not resolving anything. I am thinking either 02 sensor or coil but its odd that its so inconsistent and only happens maybe once a day when turning it on then as soon as i turn it off and back on its gone and if i drive it with it on its sluggish and rough, very odd.
 

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Hey, my 08 e90 petrol is showing the engine light and driving rough and low power but if i switch it off and lock it then put it back on it drives fine and the engine light goes.
I did [get engine codes scanned], its not consistent so theirs no codes showing, I am thinking it could be dodgy coil, would anyone who is familiar with this think thats a reasonable conclusion?
...its odd that its so inconsistent and only happens maybe once a day when turning it on then as soon as i turn it off and back on its gone and if i drive it with it on its sluggish and rough, very odd.
The symptoms you describe are consistent with a "misfire" that causes shutdown of an injector. If the SES light comes on when it's running rough, then one or more Fault Codes have been saved in the DME (Engine ECU) memory, and any such Code is still saved in Memory AFTER the SES goes out and normal running is restored (the injector is no longer disabled).

The DME is programmed to shut down the injector on a seriously misfiring cylinder to prevent fuel from being dumped into a cylinder that is NOT igniting that fuel, with the unburned fuel being dumped into the Catalytic Converter, which will damage the Cat or even cause a fire in the Cat.

You have an intermittent fault of some type, and whatever is causing the "misfire" is NOT always faulty. For instance, you could have a loose or corroded connection, in a wire or connector to a coil or injector, a plug or coil issue, an injector issue. Intermittent electrical issues take a LOT of time, diagnostic tests & thought to sort.

The FIRST step is to read any Fault Codes and Freeze Frame Data (engine conditions at time code was set, such as RPM, Load, Temp). If there IS a misfire, the fault code will tell you what cylinder has the issue.

You can then check wiring and connectors to the coil & injector on that cylinder. If nothing found, you can remove the coil from that cylinder and inspect. Remove the plug from that cylinder & inspect. Swap the coil to another cylinder (x) and the plug to a different cylinder (y) and see if the fault returns and follows ONE of those parts to cylinder (x) or (y). Diagnosis is NOT brain surgery, but it DOES require logic and thought.

Most of all, it requires a scan tool. Ideally, you would like to have a laptop with INPA or ISTA installed, where (once you learn how to use it) you can get the same information a BMW specialist shop should be able to get. However THAT setup and knowledge takes TIME and experience.

So the more realistic choice is to get a simple, cheap ($35US or less), P-code (generic) scan tool (to connect to your vehicle's OBD II Socket), and be able to Read and Clear (need both) DTCs (Diagnostic Trouble Codes) or generic P-codes. That tool can be used on ANY make or model of vehicle to read generic P-codes. Here is an example from Amazon UK:
https://www.amazon.co.uk/Autel-Auto...8-6&keywords=scan+tool&refinements=p_89:Autel

Misfire codes for a 6-cylinder engine are P0301 through P0306 (the last digit indicating the cylinder#, 1 - 6). The Scan Tool will give you the code, it will give you the Definition of the code (e.g. "P0301: Misfire, Cylinder #1") and it will also give you Freeze Frame Data (separate function).

If no local shop or parts store offers free code reading, you really need to be able to read & clear codes yourself. Investing 30 quid and an hour or two of your time to read the manual and test how to read codes and Freeze Frame Data (as well as Live Data such as Engine Temp, Alternator/electrical system voltage, O2 sensor function, etc.) will save a LOT of time, money & aggravation in the future.

If you get/record Fault Codes, and also get engine conditions at time code was set (Freeze Frame Data), then someone here can suggest next step. NO ONE who understands auto diagnostics would try to replace parts without those starting points, from which other diagnostic tests can be done.

BTW, when it comes to auto diagnostics, NEVER rely on "Quick Advice." :)

George
 

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The symptoms you describe are consistent with a "misfire" that causes shutdown of an injector. If the SES light comes on when it's running rough, then one or more Fault Codes have been saved in the DME (Engine ECU) memory, and any such Code is still saved in Memory AFTER the SES goes out and normal running is restored (the injector is no longer disabled).

The DME is programmed to shut down the injector on a seriously misfiring cylinder to prevent fuel from being dumped into a cylinder that is NOT igniting that fuel, with the unburned fuel being dumped into the Catalytic Converter, which will damage the Cat or even cause a fire in the Cat.

You have an intermittent fault of some type, and whatever is causing the "misfire" is NOT always faulty. For instance, you could have a loose or corroded connection, in a wire or connector to a coil or injector, a plug or coil issue, an injector issue. Intermittent electrical issues take a LOT of time, diagnostic tests & thought to sort.

The FIRST step is to read any Fault Codes and Freeze Frame Data (engine conditions at time code was set, such as RPM, Load, Temp). If there IS a misfire, the fault code will tell you what cylinder has the issue.

You can then check wiring and connectors to the coil & injector on that cylinder. If nothing found, you can remove the coil from that cylinder and inspect. Remove the plug from that cylinder & inspect. Swap the coil to another cylinder (x) and the plug to a different cylinder (y) and see if the fault returns and follows ONE of those parts to cylinder (x) or (y). Diagnosis is NOT brain surgery, but it DOES require logic and thought.

Most of all, it requires a scan tool. Ideally, you would like to have a laptop with INPA or ISTA installed, where (once you learn how to use it) you can get the same information a BMW specialist shop should be able to get. However THAT setup and knowledge takes TIME and experience.

So the more realistic choice is to get a simple, cheap ($35US or less), P-code (generic) scan tool (to connect to your vehicle's OBD II Socket), and be able to Read and Clear (need both) DTCs (Diagnostic Trouble Codes) or generic P-codes. That tool can be used on ANY make or model of vehicle to read generic P-codes. Here is an example from Amazon UK:
https://www.amazon.co.uk/Autel-Auto...8-6&keywords=scan+tool&refinements=p_89:Autel

Misfire codes for a 6-cylinder engine are P0301 through P0306 (the last digit indicating the cylinder#, 1 - 6). The Scan Tool will give you the code, it will give you the Definition of the code (e.g. "P0301: Misfire, Cylinder #1") and it will also give you Freeze Frame Data (separate function).

If no local shop or parts store offers free code reading, you really need to be able to read & clear codes yourself. Investing 30 quid and an hour or two of your time to read the manual and test how to read codes and Freeze Frame Data (as well as Live Data such as Engine Temp, Alternator/electrical system voltage, O2 sensor function, etc.) will save a LOT of time, money & aggravation in the future.

If you get/record Fault Codes, and also get engine conditions at time code was set (Freeze Frame Data), then someone here can suggest next step. NO ONE who understands auto diagnostics would try to replace parts without those starting points, from which other diagnostic tests can be done.

BTW, when it comes to auto diagnostics, NEVER rely on "Quick Advice." :)

George
Thanks for the advice, now I am knocked off my feet with the amount of codes I never expectedthis many 30EA, 2E85, 29CF, 2AF4, 2EF7, 30C1, 2C7F so apparently my engine is just deciding to give up
 

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Thanks for the advice, now I am knocked off my feet with the amount of codes I never expectedthis many 30EA, 2E85, 29CF, 2AF4, 2EF7, 30C1, 2C7F so apparently my engine is just deciding to give up
Well you just broke the first rule of Auto Diagnostics:

"When it comes to auto diagnostics, NEVER rely on "Quick Advice." :)

Seven codes in the DME is NOT really that bad for a vehicle that has NOT had regular proper service. See general suggestions of what they relate to below. Just address them one at a time, and all will be well. Some may be left over from prior issues.

What Scan Tool/Software did you use to read those codes?

Are they present NOW? (Many/most codes were saved at some time/mileage in the past and are NOT currently present);

Does the Scan Tool you used have the ability to read Freeze Frame Data? If so, that will tell you when/ mileage those codes were set, and after recording all that information, you simply clear all the codes, and wait to see if any of them get set again. Also, the scan tool SHOULD give you a brief definition of the code, and some also give you both the BMW FC & generic P-code.

BMW FC 29CF is the same as P0303, meaning Misfire, cylinder #3. Bentley Manual Definition:
P0303 | 29CF | Cylinder 3 Misfire Detected

Of the 7 codes you list, the only other two I find any info on in Bentley are "2AF4" Nox sensor, bank 1, and "2C7F" Post-Cat fuel trim, neither of which would be expected to cause misfire symptoms on ONE cylinder (#3). See if your scan tool (or Google Search) doesn't give a description on the other 4 I have NOT addressed. A quick Goolgle search of the other 4 indicates "2E85" & "2EF7" are related to possible water pump & Map Thermostat issues. "30EA" may be related to a Cat/Nox issue, and 30C1 is related to the Oil Control Valve on N43/N46 engines.

Regardless, the misfire on cylinder 3 is the code of the 3 identified which is consistent with the intermittent rough running and SES light.

My recommendation:
1) Get/record ALL Freeze frame or Detail information saved in DME that your scan tool/software is capable of retrieving;
2) Clear ALL codes;
3) Drive your car, with the knowledge that if it has another "misfire fit" you can pull over, turn off ignition, wait ~ 10 seconds, restart, and have normal operation restored (and NOW you have at least one Fault Code saved in Memory ;-)
4) When able, read any codes and Freeze Frame Data in DME memory, record, clear & share with the forum.

You might want to investigate the water pump & thermostat issues more closely if you have had ANY sign of engine temp problems recently, and keep an eye on your coolant level & engine temp. You can use "Hidden Menu" 7.00 to monitor actual engine temp on your instrument cluster as you drive:
http://e90.wikifoundry.com/page/BC+hidden+menus

Although anything is possible, it is likely that the same 29CF/P0303 fault code will recur, and if it does, then plug & coil inspection & swapping may be the next step. If you're game, we can walk you through that DIY process. If not, at least we can suggest what to have your local shop do.

George
 

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If it's a bad coil you should be able to kick the light on by revving the engine high up.

Sent from my SAMSUNG-SM-G900A using Bimmerfest mobile app
Yet my own experience with a bad coil was that it would run fine until I tried to accelerate a bit more than usual (like stepping on it as one gets onto a highway entrance, or to pass someone) and then there would be a stumble, with a CEL, and one could clear it by pulling over to the side of the road and restarting the engine!

Using Carly I would get an error that I had Cyl 4 misfire.
 
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