Killing myself over spark issues

pelaeon · 01-15-2007, 11:49 AM

I've done the 5 minute test.

Coil (brand new) is getting 12v at both terminals.

DME relay is brand new

Injectors have voltage

My tach does not jump when i crank. No spark when i pull plugs and set them on intake. No spark when i run a plug directly to coil bypassing rotor.

I just (today) got 2 new speed/reference sensors. Installed them, and still no spark. The guy who owned my car last has obviously messed with the old sensors before. One of the female (computer side) connectors was cut off and replaced with female quick connect ends so they will still slip on the sensor male connector. This was how it's been since i bought the car, so the system works. Luckily he didn't cut much away, and the majority of the wires are still in their shielded cable.

I've tried every possible variation of connecting the sensors, and i get nothing; No spark, no tach jump.

Any help or ideas would be appreciated. I'm just at my last straw...

pelaeon · 01-15-2007, 11:55 AM

Also i have no screws to hold the sensors down, the car has never had them. (i just discovered all of this since i've been trying to get this problem fixed.... since new years day) It ran fine without them, but... who knows.. just thought i'd add to the information about my issue.

Razorback1980 · Razorback1980's Garage

Problem is more than likely sensor wiring or gap and if that fails, then it's a computer problem. I don't know of a way to test the computer but I'll check my service manual and see what I can find. Are you sure you have the wires connected properly? Have you compared the wiring the the electrical diagrams here on Pelican? I also think it's important to get that screw in there and have those sensors the proper distance from the flywheel pins. Did you reset the sensor gaps? Is there an alarm on this car?

pelaeon · 01-15-2007, 12:21 PM

I did not regap as i just replaced the old sensors (which were working fine without a securing bolt) with two new ones. I never loosened the housing they sit in. I compared the wires to the original bracket wiring by pulling the little rubber boot back to see the order of the colored wires.

I didn't know there were diagrams on here. I shall look for them asap.

Razorback1980 · Razorback1980's Garage

Gap is probably wrong or check to make sure the set screws are still in there or not broken off.

KY944S · 01-15-2007, 12:32 PM

What year and model is it?

pelaeon · 01-15-2007, 01:39 PM

Oops. 1987 924S

Granite 944 · 01-15-2007, 04:15 PM

Ya might just have the infamous....connector pin/plastic problem. That would be the amp connector that connects to the ref/speed sensor (either side of it!). Bad wiring in between could be, so could the 9pin connector at the firewall at/above the brake booster, could even be bad at DME or associated wiring to, or............ Good luck. Follow Clark's Garage help, and all will eventually come clear. Follow it step by step. Leave NOTHING out. Otherwise, "Who knows"............Just follow the standard diagnostic procedures set forth in the FSM, or the help of

Clark's garage. "its all good!)

5 minute test is GOOD!!........IF.........done correctly!!

Otherwise..........your screwed! Follow the directions to a "T" or........?.

Good luck!

SoCal Driver · SoCal Driver's Garage

If you moved the whole bracket you have to regap the rear sensor to the flywheel's starter ring. 0.8mm or about 1/32". Don't jam the sensors down as you can bend or break off the pin that triggers the spark (front sensor). The "pin" is a set screw so it can be replaced. Can also bend the front sensor.

pelaeon · 01-15-2007, 05:46 PM

The bracket has not been touched since i have owned the car.

I'm just killing myself as to why the two new sensors (or at least just the reference) are not working. I'm going to try tapping the DME while i crank the engine in the morning, give that a shot. Maybe i'll find a loose solder joint or something. That's all i can think of to go all of a sudden.

Damn thing was running perfectly until new years eve. New years day i try to start the car and have nothing. I have always had a long crank time before the engine started, sometimes a rough idle for a few seconds right after startup, but a tap on the gas usually erased that. No clue if that is related to this issue...

ronined · 01-16-2007, 08:38 AM

Quote:

Originally posted by pelaeon
One of the female (computer side) connectors was cut off and replaced with female quick connect ends so they will still slip on the sensor male connector.

When you say "quick connect" I think of these things in the picture below. These can corrode on the inside (IMHO they are junk). I had a DPO tap into an always hot wire on an ignition relay on an MGB I once owned an with one of these connectors and the internal contacts corroded and the MG wouldn't start.

It is possible that this connector is causing your problem. I would try testing for voltage "downstream" from this connector, though I am not sure how much V should be present or when it should be present (still learning about these P-cars).

Ed