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Jeep Wrangler YJ
YJ General Discussion
Cold start problem on 92 2.5
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<blockquote data-quote="deadpool1" data-source="post: 440367" data-attributes="member: 21229"><p>PCV gasses (fumes nasty) on all these cars put a cloud of blow by gasses in the intake plenum that can land on the IAC valve cone .</p><p>this is called GUNK</p><p>and if it gets to 32f or colder, the gunk is now glue. (bad news) and super common,.</p><p>when you turn the key on, the ECU sees 32f from ECT and IAT. sensors. ( oops summer is gone)</p><p>then goes to its magic look up tables (firmware) and computes 2 things, (3 really)</p><p>it computes injection rates on predicted fuel volatility, (super important) (1fuel,2AIR,3:RPM) (and retards spark too)</p><p>and IAC air needed to best burn that cold and or old wrong season fuel. that is and RPM goal too, at first start.</p><p>just like the choke did on the 1987 with carb fueling. and the fast idle cam is the old way that IAC replaced on yours. The 87 choke plate was fuel mix.</p><p>It can not burn fuel lacking air.</p><p>There is no other air source , feet off the pedals.</p><p>end topic why it fails. (IAC)</p></blockquote><p></p>
[QUOTE="deadpool1, post: 440367, member: 21229"] PCV gasses (fumes nasty) on all these cars put a cloud of blow by gasses in the intake plenum that can land on the IAC valve cone . this is called GUNK and if it gets to 32f or colder, the gunk is now glue. (bad news) and super common,. when you turn the key on, the ECU sees 32f from ECT and IAT. sensors. ( oops summer is gone) then goes to its magic look up tables (firmware) and computes 2 things, (3 really) it computes injection rates on predicted fuel volatility, (super important) (1fuel,2AIR,3:RPM) (and retards spark too) and IAC air needed to best burn that cold and or old wrong season fuel. that is and RPM goal too, at first start. just like the choke did on the 1987 with carb fueling. and the fast idle cam is the old way that IAC replaced on yours. The 87 choke plate was fuel mix. It can not burn fuel lacking air. There is no other air source , feet off the pedals. end topic why it fails. (IAC) [/QUOTE]
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Jeep Wrangler YJ
YJ General Discussion
Cold start problem on 92 2.5
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