Date: 16 Jul 1998 20:26:49 -0400
From: (Ken Bell)
Subject: Re: 9000S Rough Idle

[Posted and mailed] If it happens only when the engine is cold, this is almost certainly NOT due to a bad O2 sensor. The system doesn't respond to the O2 sensor signal until it gets a bit warm; I think this is true of all O2 sensor / "lambda" based engine management schemes. Is there a "cold-start injector", i.e., "cold-start enrichment" on the 9000S? (I should know, but am not sure ...) If it's fine after a minute, it sounds like either something that's heat related or a problem with some phase of the engine management warmup scheme (e.g., cold-start injector, or something like that). Did you check the engine temperature sensor to see if it always reads "hot"? That would turn off any cold-start management and could lead to cold-running problems. In article <>, Dennis Park <> wrote: >After roaming through this newsgroup and for a while, I think >that it may be a problem with my O2 sensor. I've checked as many vacuum >tubes as I can and they seem fine. > >Here's the problem: >Upon starting the car, the engine will rev up to about 1,200RPM. A few >seconds later it will go down to about 200 or 100. Sometimes it will >stall. The only way I can remedy this is to step on the gas and keep a >constant RPM around 1,000 for a minute. After this,the engine stablilzes >and will not run rough for the rest of the day. The engine shakes rather >violently. I fear that I may damage it unless I remedy the problem sooner. > >Why is it that it only happens when the car has been sitting for a long >time (i.e. 5 hrs or overnight)? >There is no decrease in power while driving. Actually, it runs great with >the exception of the rough starting. > >I think it's the O2 sensor. What does it exactly do? Where is it? (I think >I know where, but I"m not sure.) > >I don't want to replace a part that doesn't need replacing and won't fix >my problem. Any help would be great. Thanks in advance. > >Dennis Park -- Ken Bell :: :: (212) 475-4976 (voice)

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