348 - SOLENOID VALVE function? | FerrariChat

348 SOLENOID VALVE function?

Discussion in '348/355' started by Ferrarium, Oct 8, 2019.

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  1. Ferrarium

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    The valves PART NUMBER: 111704 shown as #16 in the diagram, U understand they send cool air in after exhaust to burn more clean when cold, but do they affect idle when engine cold at all, perhaps the ecu sees too rich and pulls fuel etc?
     

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  2. Qavion

    Qavion F1 World Champ
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    If you're adding extra air in the exhaust stream before the 02 sensor, wouldn't the O2 sensor detect lean, not rich?

    But anyway, as I understand it, during warm-up, the engine will be running in "open loop"

    https://www.ferrarichat.com/forum/threads/code-numbers-from-scanning.577385/page-2#post-146023946
     
  3. Ferrarium

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    What I mean is if the selonoids are NOT working there would be no extra air and with the engine not at operating temps it would see rich condition is my theory. So the selonoids working adds air till the combustion is more optimal to prevent rich condition. That's why they stop when engine is warm. Again I'm reasoning here is all hence the question trying to understand. We know what it does but not why and what happens if they fail.

    Trying to track down a weird cold start idle surge and hunt phenomenon that happens most of the time but not always.

    Open loop when cold? So I can plug in a wide band there and not throw a cel and adjust each sides MAF?

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  4. Qavion

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    Sorry, no idea. I'll let the experts answer that. The window of opportunity may be insufficient unless you can fool the engine that it's still cold (false coolant temp sensor signal? (6k ohm resisitor = 0 degrees C) However, the 2.5 manual also mentions an "enrichment factor" during warm up. Different ECU maps will be used when the car has been warmed up. You may be opening up a bag of worms.
     
  5. m.stojanovic

    m.stojanovic F1 Rookie
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    The air injection (suction actually) into the exhaust manifold is just an emission thing. It probably coincides with the open loop operation which occurs during a couple of minutes from the start of a cold engine. This is the time when the air into the exhaust is enabled. I believe that the control is such that, from cold, the ECU switches into the open loop mode and switches the air on. At the point of the UCU switch to the closed loop (starts looking at the O2 sensor), the ECU probably also switches the air off. During the open loop, the ECU is not referring to the feedback from the O2 sensor so, if the air to the exhaust manifold is cut-off, there will be no ECU seeing "rich condition" (too much hydrocarbons thus too little oxygen, actually) in the exhaust and will not throw any codes or CELs.

    I have read here that some people have completely removed the air "injection" system and plugged the holes in the exhaust manifold with no problem at all.
     
  6. m.stojanovic

    m.stojanovic F1 Rookie
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  7. Ferrarium

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    Great thanks, so the weird cold engine bog to surge binary search thing my car does periodically is not related to the solenoids although I bought 2 since they were on my list of replaceable items.
     

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