[astleydave]

Hi.
I bought this 525i a couple of weeks ago only done 84K and I noticed it was running rough, I changed the plugs and found the plug on cylinder 5 was completely clean like brand new. I swapped the ingition coil with pot no 1 and it ran like a dog. Swapped it all back and changed the coil on pot 5. improved slightly but it is still missing, its worse between 2000 and 2500 revs. Could it be the injector?

 

[xXNealXx]

I would check all the vacuum hoses for air leaks first :thumbsup

 

[Mighty_5series]

As neal says air leaks are a likely culprit... also, it might be worth getting the fault codes read....:thumbsup

 

[xXNealXx]

Btw, your ISP is not TalkTalk by any chance is it? :hihi

 

[service_sad]

i think is the coil...test the coil....take the coil off but to be conected, plug in the coil a old sparkplug and start the engine and afther that but very very carfuly try to go close with the sparkplug to the car ground (any metal part i used the nut that keaps the coil) and check the spark...must be 2-3cm...if u are in doubt copared (the spark) with other spark from other coil...

regards

 

[astleydave]

Thanks for all the advice.
I have looked for an air leak cant find one. The coil has already been changed.