modded exhaust today, then ses light 5 mins later

M5 foe · 16th August 2005, 20:23

Hi everyone,
I got one of my customers (local garage) to cut out my double centre box and replace it with two 66mm (id) pipes today. I have read lots of threads about this including the one that perswaded me to do this "modifications on the cheap". I am have a superchip put in on monday so I wanted to get this done befor the rolling road test. The problem; I went to pick up the car which on inspection looked very good with regards to welding and astetics, and sounded good to. I puled out of the garage (engine warm, last led went out within 500 yards) drove 2 miles at aroud 50mph, then absolutely thrashed it for the next 2 miles on the motorway. On coming up to a round about I noticed the ses ( engine management) light come on and a very very rough idel and mass reduced power. I had to drive for about 1/4 mile befor I could turn off the engine and restart it. On restart every thing was fine, no light and a sweet burbling engine? I then spent the next hour trying to get the light to come back on, up and down the motorway, slow, fast, braking and high revving nothing except a big smile on my face. I have heard that you can make the light come on if you mess with the lambdas (dissconect then reconnect), I dont know if this is true. Someone please shed some light. Do you think the light will stay out?
P.s. Except for the light coming on this would be a great little simple upgrade. I also know BMW have spent years perfecting there cars and I'm just a monkey tring to ruin there perfection.
PLEASE HELP

P.P.s The H pipe is still in the system.

mottati · 16th August 2005, 20:29

sounds like you had a "misfire with cylinder shutdown" . Hard to say why, may or may not have been related to the exhaust work, or mafs, or cps' or .... This is one problem with the bmw's engine management, that cylinder shutdown really spoils the fun if any issues come up. Best bet would be to check codes and see if they point toward anything. I've had a similar misfire a few times, nobody has a clue why, no other codes in my case.
Mike

M5 foe · 16th August 2005, 20:32

Do you think less back pressure could have had anything to do with it?

Ashok Arora · 16th August 2005, 20:38

I think you just need a new Lambda sensor. A very inexpensive part but a common issue with aftermarket exhausts.

M5 foe · 16th August 2005, 20:40

Would the damage (lambda) come from welding or disconection do you think?

mottati · 16th August 2005, 20:42

but isn't it all working fine now? or is the ses light still on. If all is ok, don;'t worry about it unless it happens again! might have been an adaptation issue.
Mike

M5 foe · 16th August 2005, 20:47

No light, I agree about the adaption thought train (please god).

Cheers guys.

M5 foe · 17th August 2005, 21:17

Just wanted to update. Engine managment light was a electrical inconsistancy in cyl 1 (minus figure). The reading was impossible as it was a minus figure, according to the BMW mechanic.

ELEVENS · 17th August 2005, 21:52

Quote:

Originally Posted by M5 foe

...I also know BMW have spent years perfecting there cars and I'm just a monkey tring to ruin there perfection.
...

That's sooo true, you are very wise to realize it. I, too, am a monkey, but we're both moneys with great-sounding exhausts!

Don't worry about the SES light unless it gives you future probs.

sarends · 18th August 2005, 04:21

What exactly is this modification? Is there a thread with some more detail?

Quote:

Originally Posted by M5 foe

Hi everyone,
I got one of my customers (local garage) to cut out my double centre box and replace it with two 66mm (id) pipes today. I have read lots of threads about this including the one that perswaded me to do this "modifications on the cheap".

P.P.s The H pipe is still in the system.