Dan87951

OMG this car just HATES ME (car with Anderson Engine)!! After all I done for it with all the new parts and charging up all my cards for all this new stuff for it, IT still won't RUN!! What's the deal I say to P1?? I get no spark at the coil what so ever!! All the parts I have switched out with my other 951 are as follows and all have checked out. DME, KLR, DME Reley ignition reley, any reley that does with ignition, reference sensors, fuel pump is going and is pumping gas when I crank the motor, all the grounds are all good and are as new, all fuses, and even switched out the coil with my other car. The funny thing is I do NOT get 12 volts at the coil but I get 12 volts at the coil connections if I take of those connections off from the coil and test them with my DMM. So I'm assuming something is wrong here!! Because I should get 12 volts when the coil is connected to the wires. Even when cranking the car the coil registers 0 volts on the DMM. Any ideas?? Im done for the night I've been working 10-14 hours a day on this project for the past week im taking a break!! AHHHHHHHHH.

Thanks

Tom Carson

a bad ignition switch will screw up the +12 V to the coil

rig a wire from the + battery terminal to the ignition coil's thin black wire of the ignition coil...(not the green...that's where the plusing ground from the DME goes to)

also a failed FPR (they fail 'high') can cause the injector circuit of the DME to 'load down' and not supply the proper ground pulsing to the injectors and I'm assuming the ignition coil ground pulsing as well...so no spark??

pull a injector plug to see if it runs on 3 of the 4

report back...

Danno

Coil could be bad and shorted out. Or you have a short on the coil-grounding wire.

If you have +12v on the black-wire at the coil when it's disconnected, but it disappears when you plug it into the coil, then the coil has a short on the primary. Or the short could be on the grounding green wire. With the power-off and the coil-wires plugged in, make sure there is zero continuity with ground on either terminal.

Matt Sheppard

Ditto, bad coil

right?

Dan87951

Already checked the coil in the other 951 I have it started it right up! Where are these coil grounds? All I see from the wiring is the green wire from the coil goes directly to PIN 1 on the DME as a ground then the black wire goes to the ignition.

Dan87951

OK.. I tried some things today here is what I came up with. I disconnected both wires on the coil and for black wire I got ruffly 11.87 volts from the black wire to the engine, on the green wire I got 0 volts from the green wire to the engine. Now once I connect both the wires to the coil I have ignition on I get ruffly 11.8-11.9 volts from either terminal to the engine. I checked the connection at the DME terminal Pin 1 when the wires were still connected to the coil and I still got 11.8-11.9 volts from the DME terminal pin 1 the the passenger side fender bolt. I then ran a power wire from the battery to the power side of the coil which then replaced the black wire on the coil with my new power wire and still got around 12 volts on both connections. I completely confused on what I'm suppose to be getting. When ignition is on are we suppose to get 12 volts on both sides of the coil? Even as a absolute last resort I switched out the battery with the one that was in my other 951 and still no luck. What a bummer. Waited 1.5 years to get the money to finally fix the car right and it still won't work.

Dan87951

Ok I just checked my other 951 that runs very well and I get 12.08 volts on both sides of the coil so I assume this is what I need on both side with only the igntion on. Does the coil need exactly 12 volts in order to operate since my non running 951 is only pulling 11.8-11.9 volts on both sides.

89magic98

The DME provides a "switched ground" to the coil. The ground is provided _only_ when it's trying to get a spark plug to fire.

When the car is not running, I would not expect 0 volts at that terminal.

If you had a logic probe (with a pulse measurement function), and connected it across the terminals, when starting or running the car, you would see a pulsing consistent with the DME providing ground pulses to get the spark plugs to fire.

You posted a few days ago, trying to sort out your DME/engine grounds. Did you get the negative battery cable grounds correct (and the ones that go to the bellhousing from the engine harness)? If those grounds were not installed correctly, you could also get this condition.

What is the primary resistance of the coil, BTW?

Any chance you have reference/speed sensors swapped?

My advice to you is to write down each experiment that you try (what you did, what you measured) so that you don't wind up getting too badly confused.

Good luck with this. I'll keep an eye on this thread.

-Kevin

Legoland951

Are you getting an injector pulse when you are cranking? I encountered one where the injector wires were shorted and causing no spark or injector pulse because the short caused the DME to not work in the car. I would recommend getting the noid light, check for injector pulse and not just the fuel pressure, and if that's not it, then the electrical part of the ignition switch in the start position may not be supplying the power to the DME.

Al P.

I assume that when you ran a jumper from the positive side of the battery to the terminal on the coil wher the black wire is connected (as previously suggested) and cranked it you still got no spark?

Dan87951

"The DME provides a "switched ground" to the coil. The ground is provided _only_ when it's trying to get a spark plug to fire.

When the car is not running, I would not expect 0 volts at that terminal. "

/END QUOTE

Well I just checked the running 951 and with the ignition on and the coil wires disconnected from the coil the ground wire has 0 volts from the green wire (pin 1 at dme) to engine block. The black wire which is the power wire on the coil has 12 volts. This is the exact same thing I'm getting in the non running 951.

I'm aware when cranking the car I should get various high low states but how do I check it to make sure its consistant with the DME. I do have a O-scope but my probe might be bad. I think the ground wire just needs to be re-soldered on. So once I get my probe checked out I can check that.

I already tried switching the reference sensors back and forth and nothing.

How do I check to see if I'm getting a injector pulse when I'm cranking? Currently my intake manifold and fuel injectors are disconnected.

Thanks for the help.

Dan87951

Yep no spark.

89magic98

I don't think it is a valid experiment to first disconnect the coil wires, then measure the voltage between the DME "switched" ground wire and the engine block.

I think that since the DME (in normal operation)is not providing ground when the car is not running or cranking, this wire is essentially "floating" (i.e., not connected to any ground or voltage source).

The reason you see 12 volts on both sides of the coil when the wires are connected, (with the ignition on and the car not running), is that the low primary coil resistance (0.4-0.6 ohms) allows the DME "switched" ground wire's voltage to be pulled up to 12 volts. This is normal.

You could skip the oscilloscope... digital logic probe from Radio Shack (cost < $20) and connect it to the low voltage coil terminals, look for a pulse.

-Kevin

Dan87951

Someone came home for lunch and I had them in the car cranking it while I watched my DMM. The voltage will fluctuate from about 12-7 volts, I don’t think the DMM is quick enough to read the 0 volt reading but when cranking it will fluctuate in voltage on the ground side of the coil (green wire PIN1 on dme).

Perry 951

Does your car have a fatory alarm??????? This sounds oddly familiar.

I would also try cranking with the injectors hooked up. Perhaps the low load is playing games with the DME.