rough start and idle

[Her523i]

I bought a 1998 523i in Germany, European spec.. It only has 49,000 miles converted from kilometers. Sometimes I have to crank it over 2-3 times before it fires up and then it will idle rough sometimes. Does anyone have any idea what could cause this. I recently bought Bosch super plus plugs and installed them. I didn't check the gapping on them because I was told they are pregapped? Is this true. Thank you in advance.

Tracy

 

[northyork]

As a side comment: I would always recommend using the spec'd plugs and not deviating from it.

 

[bahnstormer]

was the problem before or after the plugs were in?

 

[iDriveSMG]

Well you should also recheck the gap on thespark plugs even if they said it have been pre-grap. To me, i think so. But if im wrong. sorry. Maybe you should check the spark plug wires, and rotor. But after installing Bosch spark plugs does the motor crank over easily? and still idle rough.

 

[Her523i]

The problems I listed above were all present before the spark plug change.

Thanks

 

[Kirby]

A few quick things to try:
- Add some fuel injector cleaner to the fuel tank on your next fill up
- Change the air filter

 

[connectionsav]

I have talked to many mechanics about those plugs and they always say to use the plugs that the owners manual specify. The engine was made with those plugs in mind. Also could be your O2 sensor. I am new to BMW but old hat at VW. An old VW trick was to unhook your O2 sensor, then start the car. This puts the car into "rich" or "limp" mode to get you home. If the car ran better with it unhooked then it was the O2 sensor. Word of caution though prolonged driving with the O2 sensor unhooked is not recomended even if you think it fixed the problem.