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Thread: Garage Gremlin has struck again!

  1. #1
    Registered User mjr45's Avatar
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    Default Garage Gremlin has struck again!

    My garage gremlin has once again attacked my 75 280Z with 79ZX dizzy. Last week on start up it ran like crap, very rough, wouldn't idle and died. 2 hours later it started up and ran normally, then yesterday the same rough idle and dieing on start up, waited 2 hours and the same thing, rough etc. So I thought maybe just maybe it was that the Accel coil(2nd one in a year) was toast and replaced it with an old 280 coil. Car started and ran normally, tach went to 1400 but after it warmed up the tach dropped to 0, it rose to ? RPM with acceleration but dropped to zero. I put back on the same condensor by the coil which I had removed and tach then slowly came up to about 500RPM, goosed the pedal and it dropped back to about 800RPM and bounced around from 7-900. Checked the wires to the coil from the harness and they are all good. What happened? Thanks.
    Last edited by mjr45; 07-30-2014 at 10:14 AM.
    75 280Z almost done
    49 Chevy 3100 p/u next project
    96 Dodge 2500 4X4 tows my 5th wheel

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    Registered User siteunseen's Avatar
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    This one works great with the ZX dizzy, http://www.amazon.com/Crane-Cams-730...rds=crane+ps20
    1972 240Z #918 New Sight Orange
    1977 280Z #305 Light Blue Metallic
    1972 240Z #110 Persimmons Red

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    Registered User mjr45's Avatar
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    Hey Site, do you need the Crane ballast resistor with the PS 20 coil. I have removed the old (1975) ballast resistor and ign. module. Car run OK with the Accel but it died I believe. I put the PS 20 on with no ballast resistor and the car ran better than ever, but I've read that it could cook the coil without it. Thanks.
    Mike
    75 280Z almost done
    49 Chevy 3100 p/u next project
    96 Dodge 2500 4X4 tows my 5th wheel

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    Registered User sscanf's Avatar
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    Default

    This is the coil I run on my 1976 280Z with 1979 280ZX distributor/ignition module (appropriately rewired - no ballast). $15. Runs great:

    https://www.rockauto.com/catalog/mor...205&cc=1209293

    I had a crazy tach with the old distributor/ignition module with occasional cut outs (also a ZX flavored). New distributor/ignition module fixed that problem for me ($90 + core): Product Detail

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    Quote Originally Posted by mjr45 View Post
    I put the PS 20 on with no ballast resistor and the car ran better than ever, but I've read that it could cook the coil without it.
    It's probably okay, but might not last as long as stock. The ignition module is probably also at risk, since it takes the current also. The stock 1975 specs are ~0.5 on the coil (pretty low, lower than I thought), and ~1.3 for the ballast at 68 F. 1.8 ohms total. The PS 20 is 1.4 ohms on the primary circuit (according to Summit Racing specs) , so the ignition module sees more current. Plus, without the ballast, the self-limiting current control is gone. The ballast is designed to heat up and increase resistance with time (very short times). So you have lower resistance, and no more ballast current-limiting.

    This is my current understanding. But from what I've seen many people don't really understand how the ballast resistor works, and I might be one of them. Many people run higher resistance aftermarket coils though, with no problems. Automotive engineers always design a large safety margin in to avoid failure.

    I'll bet that none of this makes you feel more comfortable.
    1976 280Z, with some minor modifications

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    Registered User mjr45's Avatar
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    Zed you're right, not any more comfortable. I run a 79 ZX dizzy with e 12-80 module and when I originally put it in the car I removed the stock ballast resistor along with the old ign. module. So after burning 2 Accel coils in the last year I went with the Crane PS 20 as some have recommended. The Crane came with a ballast resistor and I'm not sure whether to put it on or not. It simply connects from the + lead of the ign. module then to the coil. If I understand you, I should probably put the ballast resistor on simply to be safe, also, I thought the PS 20 was 1.0 ohm.
    75 280Z almost done
    49 Chevy 3100 p/u next project
    96 Dodge 2500 4X4 tows my 5th wheel

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    Sorry, I missed the part about removing the old 75 ignition module. The ZX ignition module is designed for 0.84 - 1.02 ohms, and for running with no ballast, so the PS 20 should be fine, whether it's 1.0 or 1.4 ohms. I got 1.4 from Summit Racing. I don't think that Crane really exists anymore except as a brand name.

    Do you know what the primary resistance was on your old Accel coils?

    PS20 Performance Coil

    http://www.summitracing.com/parts/crn-730-0020


    Edit - as I noted above, I'm no expert. I'm pretty sure that there's more to the whole coil-matching thing, like inductance and other concepts. That's why I just use the stock parts. The ZX system was apparently a pretty good system from the factory. Plug gap was spec'ed at ~0.040" and nobody has reported high RPM problems, like with the very early GM HIE system. The Crane coil probably doesn't get you any significant benefits, except cost and convenience if you can't find stock..
    Last edited by Zed Head; 08-08-2014 at 04:18 PM.
    1976 280Z, with some minor modifications

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    Registered User mjr45's Avatar
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    Nope no clue on Accel, just know its a POS as others have stated, I burned up 2 in year.
    75 280Z almost done
    49 Chevy 3100 p/u next project
    96 Dodge 2500 4X4 tows my 5th wheel

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    Registered User mjr45's Avatar
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    I hate to resurrect this thread, but I am frankly stumped. I replaced the Accel coil with the Crane PS 20, car ran great for a total of 3 weeks then yesterday it died on the road, had to push it home(only about 3/4 mile and mostly downhill) wouldn't start and I had a strong odor of fuel. I changed the coil back to a stock Z coil and it started and ran enough to get up the driveway. Today I hooked up the Crane again, it started and ran (at idle) with no issues. Shut it down and just now started it again, ran like crap sounded like it was missing a lot and blew tons and tons of whitish/bluish smoke. I checked for fire from the coil with a spark plug hooked to spark plug wire and got a nice fat blue spark, I also checked the timing and hasn't changed 16, fuel pressure was 37-38 at idle without vacuum, when I revved it the pressure bounced around from 15-48, but it was still running like crap. I am at a loss as what is going on, fuel pump?, bad injectors?, crud in the tank? I don't have a clear in-line filter from the tank, but when I replaced the O rings in the pump, it was clean. Help I'm lost. Thanks
    Mike
    Last edited by mjr45; 09-01-2014 at 04:39 PM.
    75 280Z almost done
    49 Chevy 3100 p/u next project
    96 Dodge 2500 4X4 tows my 5th wheel

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    These symptoms are similar to mine when I was testing a spare ECU. I got about a mile away, thew car hiccuped once, went a hundred more yards then died. Let it sit, it restarted, but then died a few more times on the way home. Ended up running home to get the original ECU which I connected with jumpers, to solve the problem and drive home. I reconnected the old ECU and it ran super-rich then died. (I think that's what happened I'd have to dig up my old thread to be sure). Eventually I replaced the two main transistors in the ECU and drove the old/bad ECU around the block and it worked.

    There have also been accounts in the past about poor solder connections on the ECU causing the same super-rich symptoms.
    1976 280Z, with some minor modifications

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    Registered User mjr45's Avatar
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    I switched the ECU from the original to a spare out of a 76 Z, so I'll try putting the original back in and see what happens. I didn't have this problem with the old one so who knows. Thanks
    75 280Z almost done
    49 Chevy 3100 p/u next project
    96 Dodge 2500 4X4 tows my 5th wheel

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    Registered User mjr45's Avatar
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    Well today I pulled the plugs they were wet and covered in black carbon, cleaned them all, checked the Temp sensor wiring to make sure it was OK with a multimeter, it wasn't the wires had come loose from the bullet connectors and were barely touching. I redid the connections and checked with the meter that all was good and moved on to the ECU. The car started and ran OK with no big issues, I tapped on the ECU and the engine sputtered, idle dropped and it died. then wouldn't start. I switched out the ECU for the original and it fired up, ran normally, even the idle remained constant, which it hadn't done with the other ECU the idle would go up on 1st start up then slowly drop to 900 then down to 600 and slowly creep back up to 850. I'll see what tomorrow brings with the original ECU back in, tapping on it made no difference on how it ran. So to sum up, maybe multiple problems causing the super rich condition, temp sensor not really working and a bad ECU. I'll keep my fingers crossed and say a prayer, if all is well, then I'll try to figure out why it still runs rich or maybe that will change, who knows. Thanks
    Mike
    Last edited by mjr45; 09-02-2014 at 03:41 PM.
    75 280Z almost done
    49 Chevy 3100 p/u next project
    96 Dodge 2500 4X4 tows my 5th wheel

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    Boat Anchor Repairman Captain Obvious's Avatar
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    I'm pullin' for ya!! Let's hope that's the end of it!

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    You kind of went backward but still got to where you need to be. Most of the threads I've seen on bad ECU's start with people tapping them to fix them, not make them go bad. But that is the sign. Reflowing the solder joints on the connector pins in the ECU itself has fixed it for some people.
    1976 280Z, with some minor modifications

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    Registered User mjr45's Avatar
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    Just for grins I'm going to dismantle the ECU I removed yesterday and see whats what, I'm a real novice with electrical stuff and reflowing solder joints may or may not be in my wheel house, I was told that when soldering, I do a good job of welding.
    75 280Z almost done
    49 Chevy 3100 p/u next project
    96 Dodge 2500 4X4 tows my 5th wheel

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    The common problem appears to be where the wires to the connector bend and poke in to their holes. They flex and fatigue over time. I think that you'll need a magnifying glass to see any cracks.

    FastWoman reflowed hers, she might have some tips.
    1976 280Z, with some minor modifications

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