rough idle, 535

[canada5]

rough idle, 535: now solved!!!!

After one of the coldest days of the year in Toronto the car has a really rough idle.
It almost feels like a misfire but once the car is moving along it is not noticable.
Replaced plugs and still the same.
Dreading the thought that this could be a wire set problem( $500 )
I have checked the resistance across the terminals of the ignition coil the secondary circuit seems a lilttle out of range.
Was given a used coil to check if this is the problem but it woudn't even start the car!
Tomorrow I will start checking for vaccuum leaks if it is not too cold( no heated garage).

Any information to assist me would be greatly appreciated. Thanks

The distributor cap and rotor were both cracked. A friend showed me a trick to test for loss of spark on the cap or down the wire set. Get a spray bottle of water set to a fine mist and gently sray it on the engine while it is running. Doing this at night so you can leave the garage door open lets you see any sparks. Mine started sparking all around the cap but the wire set appeared ok.
Lots of fun removing the cap though. I had to unscrew the fan(reverse thread) and remove the fan shroud just to get the cap clear of the engine
Thanks for the input from all.

 

[wood_e]

First off you ccan get a plug wire set for under $130... look around on the net. Overnight auto parts stocks BOSCH sets for under $110 for your 5er. I would check your cold start valve. It could be a number of things causing this problem. Do you have any diagnostic codes? I would look those up first.

Coils new are under $85 from the same place. I would check your diagnostic codes first to see if you come up with anything. That should always be the first place to start before you replace anything in your engine you think is causing a problem.

 

[bahnstormer]

LOL!
the 535i is and has been notorious for a rough idle. people used to return them to the dealer
because of the sloppy idle. its not something that you can fix, u can however minimize it.
a chip from EAT helped me out a lot

 

[wood_e]

I think that he is trying to say that it has gotten worse as time progressed. I am looking at an '85 535i (to buy), and I am aware of the rough idle. He can minimize it by replacing ignition items, as well as a chip, possibly running injector cleaner may work as well, and a decarbon procedure would also help.