Quote:
Originally Posted by Trevor
“something like what you're describing is probably the gremlin” You show that you are on the right track and appreciate that an intermittent fault represents a real challenge. The proper approach its to locate the problem rather than follow the expensive route of replacing all and sundry.
I no longer have an SVX and after four years forget some of the physical details involved in respect of plug connectors and the like, therefore take this into account.
First off disconnect the 8 pin pug/socket connector in the cable running from the igniter to the coils. Measure the resistance between sockets 4,1,7 and socket 3. Also between 5,2,8 and 6. That is between the wiring going to the coils and I am depending on a diagram in this respect.
Set your meter for the lowest available ohms reading and the readings should fall between 0.7 and 0.85 ohms, taking into account the connecting wire resistance. Make sure you do not touch the probe ends as your body will record a reading. If you are using a digital meter, connect the probe ends together and note the resistance of the included probe leads so that this can be deducted and allowed for within the tested circuit.
If possible make secure connections to the sockets by wedging in the meter probe tips so that you can wriggle the wiring to the coils about while a reading is registered in order to detect an intermittent situation, i.e. connection, wire or coil winding.
Next, using the highest ohms reeding, test all pin outs for a possible short circuit to ground, again while moving things about.
Report the results and we can move on with the diagnosis. You have a curly one which will test your patience, and mine. LOL
PS It would have been best to carry out these tests with a hot engine but I gather yours is NBG.
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Thanks for your suggestions - I have some data and some questions. My connector going from the igniter to the coils has only 7 pins, not 8. Six of the pins go to the coils, and one is "ground" which appears to be generated from the case of the igniter as it is bolted to the firewall. So I'm not quite sure what your pin #s indicate, or what you mean by "that is between the wiring going to the coils." I have a digital multimeter that automatically reads in ohms, kilo-ohms (Kohm), or mega-ohms (Mohm) depending on what resistance it finds - the resistance reading with the probe leads touched together is very small - about 0.8 ohms. I tried connecting each of the 6 coil pin-outs to the ground pin, and they are all about 0.67 Mohm. I also tried measuring each of the 6 coil pin-outs to actual ground (the negative battery terminal, with a fully charged battery hooked up), and they were also all around 0.67 Mohm. This seems odd to me, since it implies that the coils are already somehow "grounded" (maybe just by being connected to the spark plugs that are in the grounded engine block) without the "ground" pin being connected to a "case-grounded" igniter. I'm not sure whether these numbers are helpful, since I'm not sure what the pin designations are on the diagram you're referring to.
Anyway, I also tried measuring the resistance between each coil pin-out and each of the other coil pin-outs to see is somehow one or more of those wires were rubbing together, and got a very high value, about 12.3 Mohm, for all the combinations.
Also, I tried all of the above while shaking/wiggling the wires around, but never got a hint of an intermittent open or short circuit.
To answer other concerns: this seems to be the only electrical problem the car has - everything else works, from the radio to the head and tail lights, windows, wipers, etc.
I have not checked for an over-charging alternator, as the car currently will not start, but will do so immediately after getting it started, assuming that will eventually happen!