Intermittent unstable idle

Ghassan · Post by **Ghassan** » 07 Apr 2006, 19:37

Hi,

Sometimes when I brake really hard and the rpms drop to idle, they sometimes don't stablize quickly at idle speed and on occasion have dropped below idle and I get a funny vibration associated with uneven idling. This happens about once a month. I did a search but did not get a conclusive answer.

1. Anybody know if this is a common problem?
2. Is there an idle control valve that deserves some attention? I could be wrong but I believe that we don't have an idle control valve and the idle speed is adjusted by the engine management computer?
3. If this is relevant (it may not be): Last year when starting up the car in frigid weather (-26 deg C or -15 deg F) in the morning, I let the engine free idle for about 20 seconds. After this period elapsed, I placed the shifter in "D" and the engine immediately stalled. (The drivetrain loading seemed to stall the engine). I restarted and revved the engine a bit and after that it did not stall. I have always followed the same 20second procedure in cold weather starts in the past and have never had problems as such in the past. This winter year, I used some injection cleaner. Then when the temp fell down to -23 deg C (or -10 deg F), I followed the same 20second procedure and the engine did not stall. I never had no-start or hard start conditions regardless of cold weather even on those particular days when the car engine stalled after placing the shifter in "D". I only use premium gasoline (91 octane) exclusively on my car.

My car is:
1998 S70 T5 (1997 Jan build date).
270,000km, Auto tranny.

Post by **JRL** » 07 Apr 2006, 21:06

Could be the mass air flow sensor

Post by **MadeInJapan** » 07 Apr 2006, 22:08

Throttle body cleaning needed?

Post by **JRL** » 08 Apr 2006, 05:46

MadeInJapan wrote:Throttle body cleaning needed?

That too

Ghassan · Post by **Ghassan** » 08 Apr 2006, 09:35

hi,

I forgot to tell you guys. Upon my complaint, the dealer cleaned the throttle body but it appeared clean already. Secondly, as far as the mass air flow sensor is concerned, correct me if I'm wrong but I believe a fault the maf would be detected by OBDII? The dealer also scanned the obdii for fault codes and none were present.

Post by **JRL** » 08 Apr 2006, 09:36

Ghassan wrote:hi,

I forgot to tell you guys. Upon my complaint, the dealer cleaned the throttle body but it appeared clean already. Secondly, as far as the mass air flow sensor is concerned, correct me if I'm wrong but I believe a fault the maf would be detected by OBDII? The dealer also scanned the obdii for fault codes and none were present.

Not always

95autoturbo · Post by **95autoturbo** » 08 Apr 2006, 21:41

1. solid battery connection

2. ecu hose cracks should be checked and sealed

3. fuel filter, and some fuel injector treatment

are a few things that can always use checking.