Cold-start issue: Ah-HA! *update 1/22/06*

[Minami Kotaro]

I finally pegged it today.

My spark during cranking is very, very weak. I'm talking so weak I can barely feel it if I let the coil wire spark into my thumb (don't ever try that, by the way). So weak I can barely even see the spark if I unplug the coil wire and ground it against something in the engine bay. I'm talking weak, friends.

(For comparison, I got shocked in the same thumb, by the same coil, through the same wire, with the same Ignitor unit when the car was carbureted and it was so strong my hand was paralyzed for a few minutes.)

I'm also not getting a spark with every injection event; I'd say one every other injection event. Dad's carbureted Bug, cranking at about the same RPM, easily has twice as many sparks.

This must have been my problem all along. It could also be why the new, stronger battery helped so much until it got really cold.

I'm running a Pertronix Ignitor II, a Pertronix 45,000 volt coil, and triggering it with a 4-pin HEI setup. I'm running 024s9 code.

I'll attempt to haul my desktop out to the shop and get an MSQ and cranking datalog tomorrow after work.

The engine is very strong and smooth when running so I'm certain I only have weak spark during cranking.

[natesully]

Why don't you measure coil or module voltage while a friend cranks? That seems like one obvious answer. Also, watch the battery voltage on MS while your crank. I would guess that this is either a lack of power, or some crazy wiring issue where the crank switch is sucking power or shorting something.

IIRC, HEI is a dumb module but sets its own dwell during crank, so dwell should be OK.

[Minami Kotaro]

Ok, Dad and I measured the voltage at the coil.

Key on, no cranking: 12.1 volts
Cranking: 7 volts, spikes to 10 volts

Time for some re-wiring. This is all very exciting. I might end up with a car that starts! Imagine that.

[GjMan]

Check that starter. If it's going bad, it can draw way too much current.

[mops]

I had similar problem.

Was cranking, but as the fuel and spark were supposed to come on everything was dying.

my cranking voltage as reported by MS was getting as low as 6.5V, at which point ms was restarting.

replaced the battery and viola! starts every time now

[Minami Kotaro]

We did some rewiring. There is now 11.4 volts at the coil during cranking.

It still floods and won't start. I turned my cranking pulsewidth down to 3 ms, same as the pw @ 160, my WUE are all 100%, no ASE, and it floods just the same.

Next up is replacing the starter. If that doesn't do it, the EDIS is going on. If it still won't start after that, I'm out of ideas.

my cranking voltage as reported by MS was getting as low as 6.5V, at which point ms was restarting

My voltage in realtime display never gets above 3 or 4 volts. When I measure directly with the multimeter, however, I get 12 volts or above.

[mops]

My voltage in realtime display never gets above 3 or 4 volts. When I measure directly with the multimeter, however, I get 12 volts or above.

This doesnt sound right.... I would be concerned and try to understand why is that and possibly troubleshoot. MS voltage monitoring is very good and very qick (i.e. you will be able to nitoce spikes, as it will drop momentairly).

multimeters are heavily damped therefore will not normally show quick spikes down (which might happen when. e.g. you are charging coil)

did you tried to measure with multimeter the cranking voltage ? ot the voltage coil sees while cranking ? even on good battery cranking voltage should drop to below 11 volts, and over 10 is normal.


did you try playing with dwell settings on the coil ??? maby not enough charging time ? maby it was weak to start with... make sure you try different batter, just to eliminate it as a possibility or the cause.

[Minami Kotaro]

This doesnt sound right.... I would be concerned and try to understand why is that and possibly troubleshoot. MS voltage monitoring is very good and very qick (i.e. you will be able to nitoce spikes, as it will drop momentairly).

multimeters are heavily damped therefore will not normally show quick spikes down (which might happen when. e.g. you are charging coil)

It's always been that way. Key on? 3 or 4 volts. Cranking? 3 or 4 volts. Running? 3 or 4 volts.

That can't be right, since my MS works and doesn't reset.

Voltage readout in realtime display will climb with the tps reading, though. No throttle = 3 or 4 volts. At full throttle, it finally gets to 12 volts, sometimes as high as 16.

EDIT: Same behavior on the stim. TPS pot turned all the way down = ~6 volts. TPS pot all the way up = ~18 volts.

[Minami Kotaro]

The starter wasn't the problem, so it's time to switch over to EDIS and see if that makes any difference.

I also need a new CHT. The one I have doesn't read anywhere near the correct temperature.