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348 starter again

Discussion in 'Technical Q&A' started by SFchallenge, Jul 25, 2005.

  1. SFchallenge

    SFchallenge F1 World Champ

    Jun 28, 2004
    11,930
    Sgp, KL, HK & London
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    Jon Wijaya
    Hi guys. I've just done a 30000km major on my RHD '90 348TB. It has NipponDenso alternator which is getting 12-13.5V when car's running. The battery is fresh, 3 weeks young. The old negative connection has been re-wired & upgraded with a new switch while the positive connection under the airbox has been cleaned. All wires to the starter has been replaced with a new relay. So electrical issues supposed to be out. Fuel is fresh & I have new Airflowmeters, airfilter, fuel lines, fuel filters, oil. Clutch is few months old & grease on flywheel is re-packed. Engine has been tuned & balanced. Plugs & cables+PowerChip ECUs are few months old only.

    Here's the 2 problems. #1 I have to crank a few times to get it started which wasn't a problem before the major & sometimes, I have to press the accelerator to get it up. Sometimes, it starts first crank. I was told the starter is old & lazy though it's getting full 12V. I'm ordering a rebuilt starter from US for US$600 or exchange @ $450. Then, today: Nothing came up when I crank, no sound except two clicking sound. Absolutely silent. My friend came over with a bare wire, hook up the starter to the body? & it immediately cranked up but we had to try many times before it fires up. Now, I can use the key to crank it again. I was told that the relay is spoilt but starter's fine. So, what's the problem? Starter or relay? Why do I have to crank so many times now it almost flattens the battery before firing. Could it be weak fuel pumps? I remembered Jeff did a re-wiring using a starter button to bypass the relays.

    #2 Then, during morning cold starts. I get the idling fluctuating after about 5mins & so bad it kills the engine sometimes. It's fine when it's fully warmed up.

    What can I do to solve these headaches?
     
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  3. No Doubt

    No Doubt Six Time F1 World Champ
    Consultant

    May 21, 2005
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    Mr. Sideways
    I don't know if this is your problem (or one of them), but I can tell you that 348's hate starting with a lean mixture. I had to pop the blue caps off of the two MAFs and turn the screw underneath each to enrich my mixture for easy starts and smooth idles, for instance.

    You'll need an Ohm-meter. Remove the black data cables to the MAF's. The outermost pins on each extreme side of the MAFs, pins #1 and #6, will tell you the resistance of your MAF. Measure your resistance first prior to turning the fuel mixture screws. This will give you a baseline.

    Factory pre-set value is 383 Ohms. As you turn your fuel mixture screws, you'll change this resistance value. You'll want both MAF's to have the same resistance value, so if you set one at 400 Ohms then the other should be 400, too.

    You do NOT have to reset your ECU's after these fuel mixture changes.

    Fortunately this is a cheap mod/test/fix. No parts. Not much of your labor, either.

    As for your starter, make sure that your gear-shift is in Neutral *and* that your clutch is depressed (this should give you a better chance of getting the starter safety switch to work).
     
  4. ernie

    ernie Two Time F1 World Champ
    Lifetime Rossa Owner

    Nov 19, 2001
    22,062
    The Brickyard
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    The Bad Guy
    If you have the bullet style connector, it will cause the no start problem with the clicking noise. What you need to do is replace it with a solid cable going from the battery to the starter.
     
  5. SFchallenge

    SFchallenge F1 World Champ

    Jun 28, 2004
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    Jon Wijaya
    This is something new! I'll go get an Ohm-meter to try & upgrade the positive cable as well. Is there a solution to a one-start ignition? I feel so good when I get back to my '03 Merc, all the comfort & reliability.

    Wait, how do I know if it's a rich or lean mixture? Anti-clockwise/clockwise turns on the screws or i there a specific ohms or do I need to hook up to a Co testor? Thanks again.
     
  6. No Doubt

    No Doubt Six Time F1 World Champ
    Consultant

    May 21, 2005
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    Mr. Sideways

    Clockwise thickens your air versus fuel. Counterclockwise thickens your fuel. You don't have to turn the mixture screws very far, either. An 1/8 of a turn (45 degrees) makes a big difference in mixture.

    Measure your initial resistance on both MAFs. Turn your mixture screws counterclockwise, setting both MAFs to the same resistance value while making your mixture richer...then just try to start your 348. If your engine turns more than 5 times (that "ungh, ungh" sound...count each one), you're still too lean (if mixture is your starting problem, anyway)...so adjust some more. With correct mixture, correct fuel pressure, adequate air and spark, 348's start up quickly on the fisrt time, hot or cold.

    If your RPMs take forever to rev while you drive, then you are too rich. Turn your mixture screws back the other way.

    If your problem turns out to not be your mixture, you can always turn your two mixture screws each back to your original setting. Also, the factory baseline is 383 Ohms.

    If you adjust your mixture *way* past normal (either way, too rich or too lean), then you'll trigger a check engine light (or two). No big deal, just turn your mixture screws back the other way.
     
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  8. ernie

    ernie Two Time F1 World Champ
    Lifetime Rossa Owner

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    For this one it sounds like your ecu's need to relearn the warm up process.

    Do this when the engine is cold.

    Disconnect the battery for about :15 seconds then reconnect it.

    Now start the car but DO NOT touch anything. Let the car warm up by itself.

    Let the car idle for about 15 minutes, or until the cooling fans kick on at least once.


    Any time the battery is disconnect you will need go through this process.
     
  9. SFchallenge

    SFchallenge F1 World Champ

    Jun 28, 2004
    11,930
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    Jon Wijaya
    #7 SFchallenge, Jul 27, 2005
    Last edited by a moderator: Sep 7, 2017
    Hi, is that where I should adjust the screws? Sorry, but I don't even know how to use the digital multi-meter which I just bought. I know how to measure voltage only. My meter has selection for 20, 200, 2000 ohms. I touched the pins on the MAF with the positive (Red) wire & negative (black) on the metal body. From left to right=#1 to 6 no reactions but #2 shows 0.23 ohms. This is done when the engine is off anyway, the engine shuts down when the black cable is removed. I've tested them with the key turned on & off getting same results. I've attched two pictures & wonder if the blue spots are where I should adjust? I know there's two nuts in front that's for adjusting mixture/CO2.


    #2 probem. Then, during morning cold starts. I get the idling fluctuating after about 5mins & so bad it kills the engine sometimes. It's fine when it's fully warmed up.

    Don't think it's got to do with the ECUs as it happens everytime when the engine is cold. I've tried that method many times but it doesn't work. I'm on 2.5 motronic.
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  10. ernie

    ernie Two Time F1 World Champ
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    Nov 19, 2001
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  11. NYCFERRARIS

    NYCFERRARIS Formula Junior

    Mar 2, 2004
    999
    sent them my MAF and in one day they sent it back to me rebuilt to factory spec..solved a ton of starting, driving, idling problems... also check fuel injectors..I found 2 feeble ones.. remember these cars are OLD and these parts are failing and they make you crazy..
     
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  13. ernie

    ernie Two Time F1 World Champ
    Lifetime Rossa Owner

    Nov 19, 2001
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    Was that $189 for both?
     
  14. Jeff Pintler

    Jeff Pintler Formula Junior

    Jul 20, 2005
    528
    Richland
    Full Name:
    Jeff Pintler
    If I am reading the post correctly, the symptom is the motor isn't cranking over, except for some clicking noises. If that is the case, then maybe the starter soleniod isn't getting enough current, ie a voltage drop from the ignition switch all the way back to the motor. My 89 348tb came with a huge contactor style relay that was a factory fix I think. The output terminals are connected between the battery connection on the starter and the solenoid contact on the starter. The wire from the ignition switch connects to the contactor along with a connection to chasis ground. This thing is mounted on the pass side kinda behind the ignition heat sink/module. Hope this helps. Jeff
     
  15. fatbillybob

    fatbillybob F1 World Champ
    Consultant Owner

    Aug 10, 2002
    19,998
    socal
    I don't think these are the problems based on your first post. You have a connection problem disturbed during your major service. Disconnect and reconnect every major service connect first.
     

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