Im getting no spark, but the injectors are firing while cranking. i have tried cps, tested relays, checked coil resistance and power, checked engine grounds, the fusible link, and pulled cap off to look at the rotor and all was good. Lind of stumped right now maybe the coil sent a bunch of voltage back to the ecu? I know it's possible bit very unlikely. Help would be much appreciated!
You have an e36?
What does your crank sensor measure?
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Its an e30, M20b25. cps was at 560 ohms.
Mods will move you to the correct sub forum.
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Yeah thats what i was thinking i just wanted to make sure and get some other people’s opinions before i spend a couple hundred on one of those. Ill try the ecu first since the ignition coil is testing right. Thanks!
Motronic M1.3 never fails
If the coil is "testing right" then you have spark at the distributor correct?
You confirmed that terminal 15 on the coil has 12 Volts (Power going in to Coil) then move down to check spark at distributor. pull coil wire - do you have spark?
If not - then try a new coil. If you do then test rotor, test wires - follow the spark.
Motronic uses the pulse sensor to know fuel and timing - you have the fuel injectors firing - The fuel injector is a magnetically operated solenoid valve that is actuated by the ECU.
so most likely the ECU is doing its part.
Here is a good explanation from Shogun. - Good write up on the basic function of the Motronic ECU
Basic ECU operation
A permanent voltage supply is made from the vehicle battery to pin 18 of the ECU. This allows the self-diagnostic function to retain data of an intermittent nature. Once the ignition is switched on, a voltage supply to ECU pin 27 (not 1987 M1.1) and to the ignition coil is made from the ignition switch. This causes the ECU to connect pin 36 to earth, so actuating the main fuel injection relay. A relay switched voltage supply is thus made to ECU pin 37, from terminal 87 of the main fuel injection relay. The 1987 M1.1 system relay is connected to earth and not to the ECU. However, once the ignition is switched on the relay operation is similar to later models.
The majority of sensors (other than those that generate a voltage such the CAS, CID, KS and OS), are now provided with a 5.0 volt reference supply from a relevant pin on the ECU. When the engine is cranked or run, a speed signal from the CAS causes the ECU to earth pin 3 so that the fuel pump will run. Ignition and injection functions are also activated. All actuators (Injectors, ISCV, CFSV etc), are supplied with nbv from the main relay and the ECU completes the circuit by pulsing the relevant actuator wire to earth.
https://www.bimmerforums.com/forum/s...ic-1-1-1-3-BMW
1974 Fiat 124SC
1981 Porsche 911SC
1990 BMW 325IX, 1991 BMW 325IC, & 1991 BMW 325I
2002 BMW 325I
2012 BMW X3
I have confirmed i have no spark. Coil has 12v with the ignition on, but no power comes out. Do i try a new coil even though the resistance is in spec?
Ok - Confirmed no spark getting to distributor. (not just no spark getting to plugs)
Coil Primary resistance between 1 and 15 is around .5 ohms?
Pulse Sensor tested at 540 +- 50 ohms? (terminals 1 and 2) You have a 1989 - single sensor down at front of engine - this can be tested at the ECU - Pins 48 and 47 should show the same resistance.
Do you have access to another coil? If yes - do a switch. If you have to purchase - you can do a simple bench test to see if the coil is working: https://www.youtube.com/watch?v=oc941J0wh0Y
You can check the Motronic 1.3(?) computer by doing a few simple pinout tests. (click on the links of the yellow font)
https://www.e30zone.net/e30wiki/index.php/ECU_Pinouts
If you have access to another ECU - you could plug it that in as 82eye suggested.
1974 Fiat 124SC
1981 Porsche 911SC
1990 BMW 325IX, 1991 BMW 325IC, & 1991 BMW 325I
2002 BMW 325I
2012 BMW X3
Also - Just to add - Reading your other threads - did you take the head off to replace a broken stud? and then you have not been able to have the engine run smoothly?
One thing to double check is your timing marks (cam vs crank) - if the ECU checks out and the coil checks out and you still have no spark - then your timing marks are probably off. The initial startup is based off the crankshaft position sensor. If the ECU does not receive a signal - you'll have a no start issue.
1974 Fiat 124SC
1981 Porsche 911SC
1990 BMW 325IX, 1991 BMW 325IC, & 1991 BMW 325I
2002 BMW 325I
2012 BMW X3
The issue was fixed by messing with the engine wiring plugs. I will have to replace them at some point since it is losing contact for no apparent reason.
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