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Re: Message for john p re runability probs w/ '85 T Posted by RS [Email] ![]() ![]() ![]() In Reply to: Re: Message for john p re runability probs w/ '85 T, john p, Wed, 2 Oct 2002 15:25:50 Members do not see ads below this line. - Help Keep This Site Online - Signup |
I suspect that, when it's just been started, it runs rich enough that the vacuum leak is insignificant.
After the NTC sensor tells the ECU that it's warmed up enough, it leans the fuel/air mixture enough that the vacuum leak becomes significant. To my mind, the knocking you mentioned earlier indicates a severly lean mixture. The ECU swings the AIC valve open and closed to maintain idle speed but it doesn't have a reference to compensate for for the flow of air introduced by the vacuum leak because that flow changes with the vacuum in the intake manifold.
AFAIK, the O2 sensor doesn't figure into the control until the TPS indicates that the throttle is opened up.
posted by 66.21.16...
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