1997 318Ti Intermittent 1-2s loss of power

[Wlodek]

For the last 4 months, my 318Ti has had problems starting while the engine is hot. No problems when cold. Local BMW told me it could be a sticky idle valve. Now the problem has escalated to loosing engine power for 1-2 sec while driving. Again, it seems to happen when the engine is warmed up.

I had very similar problems with my Maxima, when O2 sensor was bad, and second time when air flow sensor malfunctioned.

In my 318Ti, could this be the sticky idle valve? Could this be air flow meter or O2 sensor? How to diagnose what the problem is?

I've just read fault codes using Peake R5/FCX-II tool and they are:

50 - Secondary air controls
70 - Camshaft position sensor

Thank you for any suggestions.

Wlodek

[Jeron]

I would reset the CEL and see what codes reappear.

My bad ICV caused the car die or stumble while transitioning from idle to light throttle application. A quick stab of hte throttle wuold prevent it from dying.

[Wlodek]

Jeron,

I cleared the error codes, logged some new, and re-checked them. They are the same as before:

50 - Secondary air controls
70 - Camshaft position sensor

The car does stumble when the temp gauge needle gets exactly to mid scale, normally warm engine position. Pushing the accelerator prevents it from dying, would stumble 2-3 times, drive OK for a while, stumble again, etc. The car starts always OK when cold, rearly OK when warm - I have to push the accelerator to prewent the engine from stalling.

If this is ICV, is it easy to replace? Are any instructions or drawing available?

Thanks

[Jeron]

Did the codes reappear after a stall? I think it is possible for a stalled engine to throw unrelated codes. My bad ICV did not cause any CEL codes but it may have had a code the one or two times it stalled.

On the E36 M3 S52 engine the ICV is easy to intall but the part is $100.

Look like yours is #9 here
http://www.realoem.com/bmw/showparts.do?model=CG73&mospid=47506&btnr=13_0402&hg=13&fg=15

I'd hate to see you replace an expensive part but that's probably what you mechanic will do if they suggested that the ICV might be the problem.

On mine I took it off and cleaned it with carb cleaner and it made the problem worse so I knew it was bad. You might try the same. Also mine had dead spots (electrically the ohms disappeared) through its range of motion.

[Wlodek]

Jeron,

Thank you for the guidance and the drawing. I will call the local dealer about the part and try to replace it during the weekend.

You brought my attention to these codes timing: the check engine light did not light up when the car stumbled, but a good 10 min later...

I had this 50-secondary air controls forever. I replaced visibly broken: one of the thin rubber air hoses, and a thicker 1/2" plastic tube. It did not help I am not sure what to check next. Spray soapy water on all the lines and look for bubbles..

Thanks for the drawing. It helps a lot.

Włodek

[Jeron]

Maybe the seconmdary controls refers to the Secondary Air Pump system like I have on my E36. It sounds like a blow dryer and blows air into the exhaust after a dead cold start for less than 1 minute then shuts off.

My idle is rough and wants to die when blipping the throttle during this time but it goes completely away when the secondary air pump shuts off. I ran a bottle of Techron a month ago and it went away during that tankfull but came back. A second bottle has had no effect.

Someone posted a link to an OBD2 website that secializes in good descriptions of OBS2 codes. The URL was something like OBD2-codes.com or something similar to that. Search for it, if you dont find it let me know.

[Wlodek]

I have replaced the Idle Control Valve. The new one did not help - the car is still stumbling when the engine reaches normal operating temperature. Starting a warm engine is also a problem. It usually dies right away - starts at the third or fourth attempt.

I have replaced the air filter as well. I noticed some drops of water coming into the filter compartment from approx 1" rubber tube going to 4" dia black plastic cylinder, joined with a 0.75" plastic tube to a vacuum system device. Drops of water were also in that tube. I dried everything the best I could. No change.

Could this engine problem be caused by a bad air flow meter (vortex) or O2 sensor? My 1992 Maxima acted in a very similar way when they went. But why does it happen only when the engine reaches the normal operating temperature? The first time is usually when the temp gage needle reaches mid of the scale.

Any suggestions?

Thank you,

Wlodek