87 328 - idle suddenly 600rpm | FerrariChat
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87 328 - idle suddenly 600rpm

Discussion in '308/328' started by Joe Stanton, Aug 15, 2021.

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  1. Joe Stanton

    Joe Stanton Karting
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    Aug 18, 2020
    51
    Central Coast area of California
    Full Name:
    Joe Stanton
    #1 Joe Stanton, Aug 15, 2021
    Hello! I have a more or less important issue I could use some insight on.... Starting the car at a destination point I noticed idle was around 500-600. Normally this is 1000-1050 or so. It ran as well as I felt it should so gave it just some concern but no alarm. This has not adjusted itself back, and I noted that the exhaust on the left side was extremely weak whereas the right side was strong.

    Some background other info that might be good to know, or totally irrelevant...

    * Had a sudden loss of power, traced to front cylinder bank coil connector loose, fixed. Naturally I checked this again, but all tight.

    * Car failing to start intermittently, friend helped diagnose and he jumped the fuel pump relay; the pump activated and the car started, this was good for several rides when it failed again, I jumped the WRONG relay, the A/C relay but car started anyhow. Friend thinks possibly key switch relay issue, but this is an unknown, and now car has properly started every time. Assume it will fail again at some point so keep a small kit with me at all times now. I am assuming fuse box PCB is getting loose solder or other points wearing out. Also have stopped using the aftermarket burglar alarm as friend said they are never installed correctly and complicate diagnosing issues; not removed as yet.

    * Getting some minor drip leaking of coolant as I park in garage, so I'll be checking hose seals; also noted sudden fluctuation of coolant temp from 180/195 up to 220 then down again on most recent drive. Could be various things, low coolant due to leak or thermostat.

    TIA
    Joe
     
  2. moysiuan

    moysiuan F1 Rookie
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    Nov 1, 2005
    4,186
    Canada
    #2 moysiuan, Aug 15, 2021
    Last edited: Aug 15, 2021
    Grab bag of thoughts...

    Any fuel smell, ie. signs of running rich at idle? My inital reaction is you are running too rich.

    500rpm is too low, the fuel injection system requires at least 900rpm in order to have the air flow that causes other injection components to function correctly. The good news if it does idle fine at that level, your car is probably in pretty good general condition, eg. compression, valve leak down etc., many cars would struggle to idle that low.

    The right left exhaust flow variation for these cars is I think normal. Does is have a cat converter, if so how many miles on the car/converter?

    Odd that you are not having other symptoms, drivability issues, etc.

    Maybe the throttle position sensor could be a cause, there is an idle setting in its rest position, the unit has to be physically adjusted in position correctly to hear the small click just off idle when the car is off. Very refined adjustment, so might be worth checking.
     
  3. Iain

    Iain F1 Rookie

    Jan 21, 2005
    3,320
    UK
    #3 Iain, Aug 15, 2021
    Sounds like you are dropping a bank intermittently - which is likely to only get worse.

    In no particular order, look for oil leaking from the distributor caps (caused by a leaking seal on the cam). Check the coil to dist cap leads for continuity (best done to include the distributor cap & the sprung connector in the middle, so remove the caps). Check all the connections at the coils. & general condition of rotors, caps, centre connector etc.

    Clean all the connections inside the caps & maybe remove the coil wire, snip a little off the end & re-seat it for good measure. While you have the caps off check continuity on all 8 leads & check your extenders for burn through

    If all that looks OK then get a replacement ignition amp module (the things on the top of the coils) & replace each one in turn to see if that makes it go away

    If that doesn't fix it then look to the coils.
     
    Joe Stanton likes this.
  4. Banzairacer

    Banzairacer Formula Junior
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    Aug 24, 2017
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    San Diego, CA
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    Sanjeev Thohan
    #4 Banzairacer, Aug 15, 2021
    Have you checked the warm-up regulator resistances.

    there is a great WUR thread in this forum

    https://www.ferrarichat.com/forum/threads/308-warm-up-regulator.410357/

    also this one from the MB folks since the CIS and WUR are MB.

    https://www.benzworld.org/threads/warm-up-regulator-wur-calibration.1372083/



    I’ve been having all kinds of issues with mine (85 308QV) and finally after a new, AUC Relay (TR relay solution with fuse on the ECU plate), fuel pump, accumulator and rebuilding the CIS that’s the only thing left that is causing hard cold starts, 2-3 stalls after initially going to ~1800-2000 rpm.
    Frequency valve wind throttle position all functioning diagnostically buzzing or clicking.
     
  5. Joe Stanton

    Joe Stanton Karting
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    Aug 18, 2020
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    Central Coast area of California
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    Joe Stanton
    #5 Joe Stanton, Aug 16, 2021
    Will take me a bit to get to this, but since I know I dropped a bank once before due to bad coil connections that would be a likely place to look for new issues or variant on previous problem. Thx, other suggestions to be look at also.
     

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