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Chickenwing · Joined: 12 Jun 2008 Posts: 45 Location: 07866

so after having trouble starting the car and the right ballast resistor smoking while finally running(never for long) im testing the coil to see if its shot

the allowable readings per Haynes:
(terminal 1&15) 1.0 to 1.35 Ohms
(terminal 1&4) 5.5 to 8.0 kOhms

My coil readings are 1.5 Ohms and 7.42 kOhms, respectivly.

Is this too far out of range for the coil to be good?

Btw im pretty sure the coil is original(car has 62k miles) and on the bottom the numbers "0 221 122 008", "627", and "KW 12V" are stamped.
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1977 924 4-speed

DOCO · Posted: Fri Aug 22, 2008 7:25 am Post subject:

the first reading is above specs and should just be changed because of that and the 2nd reading is rael close to foobar replace it
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Doco "where am i going and why am i in this handbasket"author unknown
79 924 N/A "Webster"
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"WEBB STR"

Chickenwing · Joined: 12 Jun 2008 Posts: 45 Location: 07866

thank you. nice and simple.

would going with a non oem(aka non-bosche) coil be ok? my local autoparts store has some coils in the $50-80 range or i can get a MSD Blaster2/3 coil.

i did some research but no clear answers, only mentions of it not being worth as an upgrade.
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1977 924 4-speed

Ozzie · Posted: Fri Aug 22, 2008 12:27 pm Post subject:

When dealing with low ohms readings always short the leads together to check the meter reads zero first.
(my leads read 2 ohms on their own)
You have to subtract any reading you get from the total if you cant 'zero' the meter.
Also take into account any corrosion and clean the spots you are testing.

As for the coil, you have to go genuine or similar.
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Porsche 924 1984 (UK import) NA
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Engineer of Electro/Mechanical Systems Maintenance

RC · Joined: 25 Mar 2007 Posts: 2637 Location: Australia

+1 to ^ re meter leads.

Your coil is probably fine IMO.

A generic resistor type coil should be OK too but take your meter with you and ensure the primary resistance is NOT LOWER than spec. The MSD coil probably will be and likely blow your TIU.

Chickenwing · Joined: 12 Jun 2008 Posts: 45 Location: 07866

hmm well it seems the leads do have .1 ohms of resistance.

time to check the rest of the stuff i guess ...
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1977 924 4-speed

Chickenwing · Joined: 12 Jun 2008 Posts: 45 Location: 07866

well i checked the rest of the electrical system and everything gets the correct readings ...

does the grounding cable to the battery usually get hot when u try to start the car??????
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1977 924 4-speed

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

On other cars, no. I'm not sure about the Porsche. To me that indicates a lot of resistance to current flow. I would probably replace the battery cables. Then clean and grease all of the connections in the engine bay. Make sure to clean the battery post connections as well.

Good luck!
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

Chickenwing · Joined: 12 Jun 2008 Posts: 45 Location: 07866

well i am now certain it is not a electrical problem. everything has been tested.

It might be a fuel issue ...

upon cranking no fuel shows up at the 5th injector located on the side of the intake manifold(cold car).

the fuel pump also receives only 10.7volts while cranking.

how can i tell if the fuel pump relay is bad?

any other help?
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1977 924 4-speed

Chickenwing · Joined: 12 Jun 2008 Posts: 45 Location: 07866

post 31 & 87 on the fuel pump relay ... are they supposed to be continuous ... meaning i should be able to have the meter beep when i test the 2 posts?
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1977 924 4-speed

77Porsche924 · Joined: 28 Feb 2008 Posts: 168 Location: Aldergrove B.C.

Chickenwing,

This may or may not be helpful... but here's what i know from this weekend's fun... (amusing story here)

I have a parts car and the main project.

When i took the fuel relay from the parts car (cuz it looked newer than my car's original one, eg: no rust) and put it in my car, ignition on, i could not hear the fuel pump.

When I took the original covered in rust and shoved it back in, BINGO! Fuel pump, pumpin' away.

Then i wasn't sure if I was getting fuel to the injectors, so... since it was so damned hard to get the injectors into the new inserts, i decided why not pull one of the banjo bolts from the fuel dizzy... SPISSSSHHHH...

IN DA FACE!

Fuel everywhere!

Yup, pressure in the fuel lines... they work!

<Grin>
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1977 Porsche 924
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Chickenwing · Joined: 12 Jun 2008 Posts: 45 Location: 07866

hmm. i dont have a parts car and i wonder how hard it'd be to get a new fuel pump relay. i guess thats the next step.
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1977 924 4-speed