So, this just happened. Damned electricals... | Page 2 | FerrariChat

So, this just happened. Damned electricals...

Discussion in '308/328' started by thorn, Sep 21, 2020.

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  1. yelcab

    yelcab F1 World Champ
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    Nov 29, 2001
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    Mitchell Le
    That would be a problem, for sure, and it even looks like an alternator problem (while it may not be).
     
  2. thorn

    thorn F1 Rookie
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    Aug 7, 2012
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    I think it's potentially related to the "old" alternator being bad (I rebuilt that last week). I'm also not the biggest fan of Interstate batteries; they supply the Honda OEM batteries... and those are absolute, utter garbage.

    Can't determine if this battery would cause problems downstream, or simply be a self-inflicting parasitic draw problem. Either ways, needs replacement.
     
  3. mike996

    mike996 F1 Veteran

    Jun 14, 2008
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    In the pic, is the Batt top still wet from the baking soda/water? Baking soda/water mix will conduct electricity. Dry baking soda won't and distilled water won't.

    If dry, it shouldn't conduct but for test purposes, wipe the batt top with distilled water and retest.
     
  4. thorn

    thorn F1 Rookie
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    It wasn't wet, but it may not have been cleaned enough. After reading your reply, I just did another round of soda water, and triple-wiped everything dry. Getting 0v on the case now. Case doesn't looked bulged, and the liquid level looks good inside the case. Keep the battery or exchange it (still under warranty, i believe)?
     
  5. mike996

    mike996 F1 Veteran

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    I think the batt is OK but if you are more comfortable exchanging it, I'd do that.
     
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  6. thorn

    thorn F1 Rookie
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    Honestly, if it was a customer car - I'd now test the battery and send them on their way if it passed. So, think I'll take mine to the shop tomorrow and put it on the load tester. If it passes 100%, I'll put it back in the car. No sense in condemning a battery if it's still ok, warranty or not.
     
  7. TurtleFarmer

    TurtleFarmer Karting
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    Jason S
    Agree on ruling out the battery for now. A bad battery with a good alternator does slow death, not erratic tach.

    As mentioned earlier, the erratic tach really seems like the coal mine canary. For your tach to bounce like that (w/o actual engine RPM bounces), the problem can only be coming through the electronic ignition modules. So likely either they are bad or something downstream is bad (ground, sensor pickups, coils, etc).
     
    thorn likes this.
  8. jlc308

    jlc308 Karting

    Jul 11, 2009
    120
    Irvine CA
    You have a problem with your XDI ignition unit. You need to contact Nick Forza Ferrari who is the XDI guru to troubleshoot, could be your pickup sensor at the harmonic balancer. If I recall, the XDI eliminates your digiplexes, distributors and crank sensors.
     
  9. 430tdf

    430tdf Formula Junior

    Aug 7, 2008
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    Canada
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    Brett
    Have you checked the chassis and body ground connections, a bad ground will cause all kinds of strange electrical problems. The car is old and a lot of times you will have corrosion under the connection that you can't see without taking it apart, but when driving the car vibrations and heat will accentuate the problem.
     
  10. thorn

    thorn F1 Rookie
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    #35 thorn, Sep 29, 2020
    Last edited: Sep 29, 2020
    I'm definitely going to be reaching out to Nick Forza; I don't know if he offers remote consultation, but I'll pay for it if it resolves the issue. Tomorrow I'll be double-checking the air gap of the crank sensor; I believe I've checked it before, but going to check again.

    Have thrice checked wires, grounds, etc. Everything looks fine so far... voltages are good, and everything has passed the "wiggle test". Not saying it's 100% in the clear, but so far checks out.

    One thing I noted as I was checking the fuse boxes: after the 45 mins of idle, the Fuel Pump Relay is incredibly hot. Not just warm/hot - like, the plastic casing is scalding-burn-your-fingers-off hot. So hot that it made the adjacent (driver window) relay fairly warm. Is this typical or not?
     
  11. TurtleFarmer

    TurtleFarmer Karting
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    I don't think typical, but not 100% sure -- I've never checked my relays for temp.

    However, relays in general shouldn't get scalding hot. If they do, that would indicate that either they are drawing more amps than they are rated OR that they've developed some internal resistance. The older style relays will draw ~0.3-0.4A of current on the coil portion of the relay -- or about 4-5W of power. This is enough to heat up the relay so that it's definitely warm-to-hot. However, scalding hot usually indicates that your contacts on the main path have corroded, increasing resistance and therefore generating heat.

    It's an easy fix...just replace the relay :). Also, I don't think that is likely your issue with the erratic tach. But it certainly could reduce your pump efficiency and cause fuel problems....
     
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  12. thorn

    thorn F1 Rookie
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    Background: It's been doing this "shut off when I've been driving for a hour" BS for at least a yr or two now... at one point, I replaced the XDI coil grounds and it seemed to resolve it. But, now it's back. A curious difference THIS time, however .... normally, it might shut off - then I'd start the engine (rolling down the road) and it wouldn't re-occur. This past week, it was slam fail after fail after fail - and the RPMs bounces were a brand-new symptom. Rather unsettling, actually.

    Tis an old car, and I've slowly been resolving whatever problems arise - so, possible the fuel relay (or pump) is an unrelated thing that nonetheless may be a problem.
     
  13. johnk...

    johnk... F1 World Champ
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    Doesn't mean a thing. Try measuring the resistance between the terminal and the same point on the batter case. I bet you get infinite resistance.
     
  14. thorn

    thorn F1 Rookie
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    Oh, I'd be surprised if I didn't. It's just seeing so many things here and there that are wrong, while searching for a solution for something that is so elusive.
     
  15. johnk...

    johnk... F1 World Champ
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    Nothings wrong with the battery based on that alone.
     
  16. Dr Tommy Cosgrove

    Dr Tommy Cosgrove Three Time F1 World Champ
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    Back in the late 90's mine started running like **** right out of nowhere one afternoon. I drove it running like **** to my shop and I distinctly remember Mike telling me my fuel pump realy was "hot as a firecracker" Exact words. He told me something about FIATs also "did this all the time" Exact words. He knew the problem well and what to do.

    Apparently he did because that was about 23 years ago now. The car was only 13 years old then so his fix, whatever the hell he did, worked.

    So, yeah, a hot as hell fp relay on a 308 is fairly typical at some point.
     
  17. thorn

    thorn F1 Rookie
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    Small update - things I know aren't the problem:

    - The fuel relay: replaced with a known good one, car still died on a test drive
    - The battery: cleaned, full charge, ditto.
    - The alternator: charging at 13.5v
    - The key switch: This is one I had wondered about. But, since I was test driving and expecting/hoping for the car to die on a back round, I didn't freak out as I normally do and restart the car immediately. I just left it off, and pulled off the road. Grabbed the meter and started testing various places. One new discovery - the car was NOT loosing all power. Accessory power was still present and working fine.
    - Therefore, tends to eliminate some up-stream stuff. Not completely (could have a connection that comes/goes), but so far every connector I've touched has been fine and there's no response to wiggling it.

    Possible problem:

    Lots of reading led to me take a look at the air-gap for the crank trigger sensor. I measured this morning; max allowed is .060", mine was at .055". However, the mounting bracket wasn't loose, but also wasn't exactly tight. I'm pondering the idea that heat expansion + bracket + almost-max-gap = the sensor has been drifting too far from the trigger wheel, and the engine shutting down.

    Re-gapped it to .030", and snugged down all 3 fastening points. Drove the car 25 mins home in rush hour traffic, car didn't miss a beat. Will take a few more drives before I'm willing to call it resolved, but at least this first drive was uneventful.
     
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  18. Imatk

    Imatk Formula Junior

    May 6, 2007
    290
    Awesome man... glad you figured it out... I hate electrical stuff.
     
  19. mike996

    mike996 F1 Veteran

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    I'd say that there is a definite possibility that perhaps maybe you might have found the problem. ;)
     
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  20. thorn

    thorn F1 Rookie
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    New unfortunate update: it's not the crank sensor gap. Having confirmed it to spec and being sure the bracket is tight, we took a nice drive for lunch. Car ran flawlessly.

    Finished lunch, and now sitting in a parking lot a car that dies every 10-120 seconds.

    Too angry to even call for a tow at the moment. Sent the girlfriend home in an Uber.
     
  21. JohnnyTS

    JohnnyTS Formula Junior

    Jun 3, 2012
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    Have you checked the TDC pickup sensor on the bell housing ? or maybe ever replaced it? they can also make problems when the car is hot after a drive.
     
  22. TurtleFarmer

    TurtleFarmer Karting
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    Ugh. So sorry....nothing like that feeling in the pit of your stomach when "something" is wrong with the car but you don't know what/where.

    Do you still see the strange tach symptoms? Or the car is just dying?
     
  23. mike32

    mike32 F1 Veteran

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    When it stops, are the coils both the same temp ?
     
  24. thorn

    thorn F1 Rookie
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    The stock sensors aren't used with the XDI system; it uses it's own magnetic sensor + a trigger wheel at the crank. Resistance spec on the sensor should be 600-700 ohms; mine measures at 702... so, close enough to spec that I believe the sensor isn't faulty (opinion subject to change, of course.)

    Initially, the car just died. It made it about 100 ft through the parking lot. After 10-15 mins of rest, it made it another 1/2 mile, then died. Another 10 mins of sitting, made it about 2 miles until dying. Another 25 mins of sitting, made it around 8 miles before dying. At this time point, the tach wasn't doing the 0-3K bounces I've seen. However, the last mile home was a limping nightmare - car cutting off every block, and the tach was now doing the bounces.

    New observation on the tach: because the engine is sort of struggling being "almost dead" and "trying to run", I believe the tach is just doing it's best to keep up with what's going on. In testing, I've completely disengaged the tach wiring with no ill effects - so I'm leaning towards the tach bounce as being an end-result, not necessarily part of the fail equation.

    All 4 coils felt quite normal, no difference between them. The only overly-warm component (that I can touch, without lifting the car) is the fuel pump relay. However, I swapped it with another relay yesterday in the middle of the debacle - no change in the car, so the hot relay isn't the problem. I also checked current on the fuel pump as the car was running: about 9 amps, compared to 8.3 amps when the car is cold. The circuit is rated at 15 amps, so I believe the fuel pump circuit probably isn't an issue.

    My next step will be replacing the main power line to the XDI. Right now it's connected to the post on the starter (where the alternator connects.) Going to run a line directly to the battery B+, and see if anything changes.
     
  25. mike32

    mike32 F1 Veteran

    May 13, 2016
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    Isle of man- uk
    If the starter is turning then the cable supply from the battery will be fine. Any backfiring of the engine when it decides to cut out ? If so pull the engine oil dipstick and see if the oil level has risen up, any smell of fuel on dipstick ?
     

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