Hyper_545i

Hello All,

I've noticed over the past few weeks, the idle on my 04 545i seems unstable. This happens on cold starts as well as hot starts. The car never actually stalls but it feels like it wants to. The idle seems to be at about 500rpm. I've seen it surge to about 900 as a high and down to about 400 on the low. What should the idle be? Should it be rock steady? Yesterday I got the SES Light and an Increased Emmisions message on the iDrive. A few months ago I got the same and replaced the gas cap, CCV's and the DMTL Pump. Felt fine until yesterday. I am going to get the codes read tongiht after work.

Could a bad coil(s) cause this? Alternator / Voltage regulator issue? I replaced the spark pulgs back in December with OEM. This seems to only be an issue while stopped. Driving on the highway, I have no issues or performance degradation. Any help would be appreciated. I have 106K on the clock.

H F

[QUOTE=Hyper_545i;1518773]Hello All,

I've noticed over the past few weeks, the idle on my 04 545i seems unstable. This happens on cold starts as well as hot starts. The car never actually stalls but it feels like it wants to. The idle seems to be at about 500rpm. I've seen it surge to about 900 as a high and down to about 400 on the low. What should the idle be? Should it be rock steady? Yesterday I got the SES Light and an Increased Emmisions message on the iDrive. A few months ago I got the same and replaced the gas cap, CCV's and the DMTL Pump. Felt fine until yesterday. I am going to get the codes read tongiht after work.

Could a bad coil(s) cause this? Alternator / Voltage regulator issue? I replaced the spark pulgs back in December with OEM. This seems to only be an issue while stopped. Driving on the highway, I have no issues or performance degradation. Any help would be appreciated. I have 106K on the clock.[/QUOTE

It'. Sounds to me like the it's the exact simptoms that happened to my car . It turned out to be the MAF . I delt with the irratic idle fo Almost two weeks. After that it got really crazy idle it started serging and shaking violently.. I was seriously ready to cry .. So I took it on the fwy on route to the dealer . On the fwy it ran smooth. As soon as I stopped it started getting all crazy again . Since a new MAF was installed she purrs like a kitten again

Cre8

[QUOTE=H F;1518796]Thanks for the heads up, I have a similar issue. Instead of replacing the MAF, has anyone tried cleaning it with MAF cleaner before replacing it? I have a can at home just curious before give it a squirt.

Hyper_545i

Thanks for the replies guys! I too am going to look into cleaning the MAF. I guess the codes if any will tell what the real issue is.

H F

Thanks for the heads up, I have a similar issue. Instead of replacing the MAF, has anyone tried cleaning it with MAF cleaner before replacing it? I have a can at home just curious before give it a squirt.[/QUOTE]

Cre8 ,,,, Actually I did clean my MAF but it didn't fix the problem . On my car it turned out that the circuit inside the actual plug of the sensor is what failed ..

Hyper_545i

Ok, so I got my codes read last night from Autozone. I have the following:

P0300 - Random Misfires Detected
P0304 - Cylinder 4 Misfire
P0308 - Cylinder 8 Misfire

Tuesday Night, I removed the CCV's and reinstalled. I had previously replaced these when I replaced the DMTL Pump a few months ago. I cleaned and reinstalled and went for a drive. The idle has been really good since then. I am not 100% sure the colis are bad. I may swap them with other cylinders to see if the misfire follows. If it does, I'll replace them as needed. I also had the battery and alternator tested, and they all passed. I am going to buy a code reader so I can clear the SES and see if it comes back up again.

H F

[QUOTE=Hyper_545i;1518864]Ok, so I got my codes read last night from Autozone. I have the following:

P0300 - Random Misfires Detected
P0304 - Cylinder 4 Misfire
P0308 - Cylinder 8 Misfire

Tuesday Night, I removed the CCV's and reinstalled. I had previously replaced these when I replaced the DMTL Pump a few months ago. I cleaned and reinstalled and went for a drive. The idle has been really good since then. I am not 100% sure the colis are bad. I may swap them with other cylinders to see if the misfire follows. If it does, I'll replace them as needed. I also had the battery and alternator tested, and they all passed. I am going to buy a code reader so I can clear the SES and see if it comes back up again.[/QUOTE

I thought Auto Zone stopped reading codes . Due to some issues with auto shops complaining a out it or something like that ..

Hyper_545i

Nah, they still read codes. Just are not allowed to clear them. They will also check your battery and alternator. All free of charge!

Hyper_545i

So just an update, the SES Light is off and the idle is back to where it should be. Not sure what fixed the problem. I rfemoved my CCV's that I installed a few months ago, inspected, cleaned and reinstalled. My concern was I did not seal the caps properly and there could have been a vacuum leak. The next day the SES Light turned off on the way home from work. Last night, I cleaned my MAF. Wow! Big difference! The idle is smooth and where it remember it to be. Next, I am going to add some Techron Fuel Additives on my next fill up to clean out the injectors of deposits. Hoping the issue does not return. H_F, Cre8 how did you guys make out?

H F

After changing out the MAF my car has been running good.. But I think I'm gonna take alook at my CCV's to check for built up oil in the hoses to the intake and clean them out.