help please: code C5, E8 but no SES light - The Unofficial BMW M5 Messageboard (m5board.com)

Avusblue · 15th February 2007, 03:28

A few days ago I started the car had my usual rpm-hunting between 900-1100 rpm. I know its not normal but seems to go away after about 30 or so seconds; so I don't bother with it-not yet.

The problem is that when I rev'ed the engine that one morning, I heard the a sound which resembles thumping or knocking under the car. But when the car is warm, its fine, the rev is smooth again. When I shut off the car, I heard some sounds like a servo out of battery-I didn't hear this sound before. All this and but SES light plus it drives normal when warm. When I pulled the peake reader, I got table 18-C5 and E8. I haven't cleared it yet because I wanted to see if it goes away.

I read the prev posts and discovered that someone else on the board also had a similar problem but I didn't see any solution. Another post's E8 indicted the breather valve, but SES accompanied the code. Thanks in advance for the help.

2000 with 62kmiles bonestock

mottati · 16th February 2007, 00:23

not sure what codes c5 and e8 are without my peak book. Could you give a little more info?

Avusblue · 16th February 2007, 02:43

hi-
c5 was mis fire on 2 I think.
E8 was the evaporator function check

second day its doing that. sounds like thumping or knocking on the muffler-comming from under the car. The exhaust also sounds a little louder. But when it warms up, its fine-I'm worried that if I keep driving it like that, it will damage something. thanks.

mottati · 16th February 2007, 07:13

changes in exhaust sound, rough idle and misfires are often related to a cam position sensor. Random misfire codes are not uncommon (my car has them stored all of the time, but never sets off an ses light). Those faults will not go away without clearing. The knocking sound is more concerning, you sure it isn't coming from the bottom end of the engine?
You say the car is generally running ok/strong?
Mike

Avusblue · 16th February 2007, 08:29

Mike, the car pulls strong when its warm. The idle is @~600rpm and smooth when it warms up. That sound also goes away. I drove for 40 miles with audio off just to hear the motor, doesn't seem to exhibit any unusual symptoms after it reaches normal operating temp.

The sound when cold isn't coming from the engine, but I'll check again. When I start it in the garage where its about 30* its fine, no thumping sound. But when I start it in a 10* parking lot it thumps.

Do you think that it may be the frozen oil or oil related components that maybe causing this ("coming from the bottom end of the engine")?

2 CPS, which is cheaper? Do you recommend the locals or dealer? I'll be doing the work myself.

I read on this forum that E8 (evaporative emissions purge valve) may be caused by fuel tank breather valve.