Warning lights coming on while driving

[SubZero]

My ride is E46 M54.

Yesterday, 2 minutes after driving off from cold the EML, DSC and amber Handbrake warning lights came on. Engine lost power and had to pull over. Switched off engine and started and no more problem.

Today, same thing happened again 3 times. First time from cold and the other 2x when engine was warm.

Went to PML to check. Quick diagnostics showed DSC and DME (DEM?) may be the problem, with the idle valve as a probable cause. The mechanic asked if I was using KNN filter and said the oil from the KNN may be causing the problem and advised to send ride in for full check. Also recommended to replace stock air filter as this may help eliminate unlikely causes and narrow down the troubleshooting process.

Do any of the bros here still have their old stock E46 air filter sitting around that I can borrow? A new air filter does not cost much from lobang from another post. However, I do not want to raise suspicions going in with a new air filter.

I kept my old stock air filter of old ride for 5 years without having to use it again. Now with this ride, 5 months after throwing it away I need it! Such is life!!!

Appreciate anybody who can help. Thanks.

 

[FUNMAN]

Re: Warning lights coming on while driving

bro it is the usual case PML would say go BVO for a second check.

Cheers

FUNMAN

 

[Racebred]

Re: Warning lights coming on while driving

quite possibly what happened is some maf problem. when the engine detects a big anomaly in the air fuel ratio, outside of a set tolerance level, it will go into limp home mode, which gives you only 40% of the power (explaining your power loss).

if the k&n filter is really at fault, then it's a probable cause of the k&n oil getting blown onto your MAF and screwing up the readings as it's fully dependent on current readings on the exposed wires. Then your ECU (or more specifically the DME) will think there's an abnormal AFR going into your engine and thus limits the power to prevent damage.

very often it's easily solved by restarting the engine, but if the problem persists, then it's very possible that your MAF is damaged, and you may have to get a new one if it's not cleanable. Alternatively, it could just be your MAF working up totally independent on your K&N filter, and if then, you can claim guarantee for the MAF, which could cost about $600.

One way to test if it's your MAF problem is to try to switch on your cruise control. If it refuses to be switched on, or if the green cruise control light disappears the moment you tap your brake, then it is most likely your MAF.

2nd way is to try to use left foot braking, (which only works for M54 onwards, drive by wire system) if you detect the engine cuts off power when you tap the brake, instead of both power and braking continuing, then it could also point to a faulty MAF.

hope that helps.

 

[SubZero]

Re: Warning lights coming on while driving

Thanks Racebred for such a detailed write-up and explaination.

That's what I originally thought was at fault, i.e. the MAF, and discussed with the CSA, but the diagnostics did not indicate that that was the fault but rather some idle valve thingy. Will try out what you recommended to narrow down the possible problems before sending ride in. Will have next 2 days to do so as PML is closed until Monday.

Thanks and cheers,