no start

Post Tue Jan 21, 2014 12:06 pm

Hi all, my M20B25 is not starting. Confirm got fuel but not spark. new coil n distributor n rotor. got power supply to the coil but no spark when i crank the engine. it was running 2 days before but will not start since monday. engine is cranking.HT lead n plug is new n is running well since i got her. is only the temp coolant sensor need to replace. will it be the CPS problem ?

Post Tue Jan 21, 2014 12:09 pm

Bad CPS will take out both fuel and spark, so it won't be that.

To confirm lack of spark, have you tried earthing a spark plug straight from the king lead off the coil?

Post Tue Jan 21, 2014 12:44 pm

Yes. i try that. NO spark...

Post Tue Jan 21, 2014 12:53 pm

Ok, can you do this?

http://www.e30zone.net/e30zonewiki/inde ... lb_On_Coil

Post Tue Jan 21, 2014 1:22 pm

I connect a wire from the battery positive to the coil positive n crank the engine no spark.

Post Tue Jan 21, 2014 1:28 pm

Duff ignition coil, perhaps? To test it, connect a spark plug to the central HT lead (earth the other end of the spark plug to battery '-'), then flash 12V from the car battery across the LT terminals, observing polarity.

Post Wed Jan 22, 2014 1:23 pm

connect a 12v 5w bulb to the coil, bulb NO light. connect a wire from battery positive n coil positive YES got power supply. suspect the green wire not supply power. how to check the green wire?

Post Wed Jan 22, 2014 1:50 pm

Remove the glovebox, and check that it's connected properly.

Post Wed Jan 22, 2014 1:54 pm

8565 wrote:how to check the green wire?

http://www.e30zone.net/e30zonewiki/inde ... Green_Wire

Post Thu Jan 23, 2014 11:05 am

Why my E30 got 2 sensor plug on my auto box? speed n position sensor. n my CPS on the front of the engine is connected to the checking plug mount on the side of the engine n got no function on it.

Post Thu Jan 23, 2014 12:08 pm

How old is your car? If it's 1986/87, it will have two CPS sensors on the gearbox instead of the one on the front of the engine.

On these old cars the sensor on the front of the engine is just for the diagnostic plug. However, you won't get any signal from it unless you use an oscilloscope.

But none of this is important. If you are sure you are getting fuel when you turn the key, then the CPS sensors are working. Have you checked the green wire?

Post Thu Jan 23, 2014 12:29 pm

Yes mine is 1986. no wonder i can't get reading from the front CPS sensor.

Green wire got power supply. Yes i'm sure getting fuel cause i fitted a fuel pressure gauge on the engine and gauge reading is 3 bar and fuel pump is new and running.

Post Thu Jan 23, 2014 12:38 pm

8565 wrote:connect a 12v 5w bulb to the coil, bulb NO light. connect a wire from battery positive n coil positive YES got power supply. suspect the green wire not supply power. how to check the green wire?

Have you tried starting the car with the ignition coil directly powered up this way? This would at least rule out the coil being faulty.

Post Thu Jan 23, 2014 12:58 pm

ya is a new coil just fitted no more then 2 months. even fitted back the old coil is still no spark.

Post Thu Jan 23, 2014 1:00 pm

YOur results are confusing. You say you DO have power at the green wire, but you DON'T have light on your test bulb at the coil. If you have power on the green wire, the test bulb MUST light. So one of these tests must be wrong.

Post Thu Jan 23, 2014 1:00 pm

All well and good, but have you tried starting the car with the coil directly powered from the battery?

Post Thu Jan 23, 2014 1:01 pm

try to use a multimeter check on the c101 but no pin15 in my c101.

Post Thu Jan 23, 2014 1:06 pm

first i connect the test bulb on the coil positive n coil earth the bulb not coming than i connect to the body earth and the bulb light up. this mean the green wire got power supply right?

Post Thu Jan 23, 2014 1:08 pm

yes, speedtouch i do start the car directly from the battery to the coil.

Post Thu Jan 23, 2014 1:13 pm

Sounds like you're getting the ignition-switched live to the + terminal of the coil. The - side of it is 'earthed' (pulsed) via the ECU, so maybe you have a problem with that; the '073' type was reknowned for developing faults.

The Zone Wiki troubleshooting guide states:

"This is the initial test performed on all E30 engines. It involves connecting a test bulb between pin 15 (green wire) of the ignition coil and earth (ground), to confirm the presence of 12V."

So, connecting the test lamp directly across the coil won't make it light, since it is pulsed by the ECU, hence why it only lit when you earthed one side of the lamp.