Check Engine Light & Limp Mode - The Unofficial BMW M5 Messageboard (m5board.com)

Ahmed · 30th October 2009, 09:36

Hi guys

I was told that after installing the Evosport headers, I should be expecting the CEL to come on. Alot of members did claim that this is just a nuisance and does not affect performance of the car. Well... not in my case!

I had the headers installed last Sunday, I've had no problems till last night while doing my dyno run! The CEL came on at 7800rpm on my first run. And hasn't gone away since. I even tried to disconnect the battery and reconnect 10 mins later.. but it wont go away!

Understandable, so I might need my installer to reset the fault code, and then remove my ECU to send away for remapping!

Anyways, so on my way home on the freeway, my car goes into limp mode by hesitating a few times, and then eventually I lost power and there was no throttle... so I pulled to the side and switched her off. Re-cranked her and she was running rough and died everytime.

Called the tow truck and had her taken home for the night.

My questions are:

1. Why do some members claim that the CEl did not affect driveability of their cars? Could I be having another problem other than the O2 sensors reading unusual numbers due to headers?

2. What do tuner do exactly when they remap your ECU and remove the CEL? Can there stil be limp mode with no CEL? Or once I get my ECU done, I should not have to worry about CEL or Limp Mode after that ( because of headers ). I would like someone to explain to me how all this works please.

Herea are two videos of the CEL, the first one shows the car with CEL on and a message on the screen, at this moment.. the car was runnign fine. Then in the next video, you can see me trying to crank her up after pulling to the side of the freeway.

YouTube - Limp Mode

YouTube - M5 Limp Mode

gasterus · 30th October 2009, 13:18

I've had evosport headers and does not experience any CEL. And CEL thrown by decated headers should not cause your car into limp mode. I'm suspecting you might have other issues....

Ahmed · 30th October 2009, 15:21

Are u running on stock ECU software?

gasterus · 30th October 2009, 17:21

Quote:

Originally Posted by Ahmed

Are u running on stock ECU software?

Yes, I am.

M-POWER 77 · 30th October 2009, 17:33

Ahmed, im sorry bro for your car, i hope nothing serioes, my guess is the miester pipes when combined with the evo headers will resault in severe back pressure lose! thus the ecu things something wrong is going and initiating limp mode. try removing the pipes before doing a tune, hope this will remove the cheack engine.

Ahmed · 30th October 2009, 18:08

Thanks bro

I will take it in tomorrow to haev the codes pulled just in case it's something else! I have searched threads here and have come across previous experiences of members getting the CEL on a dyno! Some have had VANOS issues, and some have had Idle Actuators issues.

Let's see what my service technician says.

Oh and let me mention that I have my stock sec. cats still in! I have only replaced the headers and cat back pipes.

Ahmed · 31st October 2009, 19:36

Oh well, turns out that my fuel pump is messed up. Off to the dealer I go tomorrow.

Rab Dog · 31st October 2009, 20:03

Ahmed 98% chance the root cause is not because of your headers and exhaust! I had a similar problem with my car on the Dyno going into limp mode and I actually had the ECU tuned, but it turned out to be an idle actuator problem. I as well reset the compter many times however as soon as I raised the RPM to about 6k the car would instantly go into limp mode. Dealer fixed my idle actuator and I ran stock tune for about 2-months with RPI headers and RPI section 1,2,3 basically straight pipes the CEL came on because of emmisions but car never went into limp mode again. Currently I have ESS 2.0 tune in my car and car is running perfectly.

The problem you might run into at the dealer is they diagnose your problem due to after market headers hopefully they will get down to the real root cause and not stop at your exhaust and headers!

Good luck!

Ahmed · 31st October 2009, 22:47

Thanks Rab Dog

I have been following your thread, and thanks to you... i had a head start as to what the possible problems might have been, and yup.... it was bang on!

Let's see what the stealers say tomorrow, hopefully they will honor the warrranty and replace the pump or actuator. I just hope its straight forward and nothing more complicated such as vanos isues or worse.

Black M5 · 31st October 2009, 22:52

And hope they have it in stock which i highly doubt they do