All kinds of ignition problems!
#1
09-05-2010, 01:36 PM
All kinds of ignition problems!
Hello all, I'm a little new to these forums, hopefully somebody here can help me.
I have a 94 Civic DX, 1.5L manual 16 valve engine.
A little background, I had been having a little bit of trouble with this vehicle before where it would run fine and then after running for a short period it wouldn't start for a while unless you left it alone for like an hour. Going back to it now it was probably a relay problem, but at the time I didn't really need the car so it ended up getting parked instead of fixed (BIG mistake). It was parlked for almost 3 years, and now has a multitude of problems:
Mainly, right now, there is no spark although there is power in the ignition coil (which is brand new) and the cap and rotor are also brand new, but there is no spark getting to any of the plugs (also new).
There is also no power getting to the fuel pump (also new) or the fuel injectors (factory as far as I can tell, but the continuity tests suggest that the injectors themselves work fine), there is simply no power being supplied through the fuel rail.
I know what you are thinking, the main relay? That was one of the first things we looked into. The relay at first didn't have continuity, but after soldering the points the relay checks out. The ignition switch was checked and continuity is also good there, something in between maybe?
Also, fuel was definitely old after three years but all of that has been drained and new fuel added, so it shouldn't be an issue (although we had old fuel move the engine early on, but it should all be gone now).
Mainly we can't figure out A.) why there is power being supplied to the ignition coil and power coming out but it isn't getting to the spark plugs and B.) why the main relay seems to be working but there is still no power going to the fuel pump or fuel injectors.
Also, we looked into the ECU, it is possible that it isn't working but there is no LED on it that everyone said will give you the error codes, it simply is not on this particular car.
Any ideas? Thanks for any help!
-Robert
I have a 94 Civic DX, 1.5L manual 16 valve engine.
A little background, I had been having a little bit of trouble with this vehicle before where it would run fine and then after running for a short period it wouldn't start for a while unless you left it alone for like an hour. Going back to it now it was probably a relay problem, but at the time I didn't really need the car so it ended up getting parked instead of fixed (BIG mistake). It was parlked for almost 3 years, and now has a multitude of problems:
Mainly, right now, there is no spark although there is power in the ignition coil (which is brand new) and the cap and rotor are also brand new, but there is no spark getting to any of the plugs (also new).
There is also no power getting to the fuel pump (also new) or the fuel injectors (factory as far as I can tell, but the continuity tests suggest that the injectors themselves work fine), there is simply no power being supplied through the fuel rail.
I know what you are thinking, the main relay? That was one of the first things we looked into. The relay at first didn't have continuity, but after soldering the points the relay checks out. The ignition switch was checked and continuity is also good there, something in between maybe?
Also, fuel was definitely old after three years but all of that has been drained and new fuel added, so it shouldn't be an issue (although we had old fuel move the engine early on, but it should all be gone now).
Mainly we can't figure out A.) why there is power being supplied to the ignition coil and power coming out but it isn't getting to the spark plugs and B.) why the main relay seems to be working but there is still no power going to the fuel pump or fuel injectors.
Also, we looked into the ECU, it is possible that it isn't working but there is no LED on it that everyone said will give you the error codes, it simply is not on this particular car.
Any ideas? Thanks for any help!
-Robert
#2
09-05-2010, 02:35 PM
LEDs were only fitted on the OBD0 system used before 1992. You have an OBD1 where the check engine light is used to read trouble codes. When you turn the key on but don't try to start, the CEL should light up for 2 seconds then go out. That generally shows the ECU is powering up and running OK. Does yours do that? If it doesn't come on at all, or doesn't go out, check the fuses (several are involved) and the ECU ground wires on the thermostat housing.
#3
09-08-2010, 06:37 AM
I see, ok that clears up the ECU thanks! I'm pretty sure the fuses are ok, but I overlooked the ground wire (mainly cuz we didn't know where it was), I will check that out. Could an ECU be causing all these problems?
#5
09-08-2010, 12:45 PM
I read somewhere that bad connection wires to the spark plugs can cause phantom problems, but can that really be the cause of this? It seems like there is no spark in any plug, not even a small one.
Could it be a crankshaft position sensor? The wires to the sensor check out but I haven't actually pulled apart the cover to get to the sensor itself.
This may be a stupid question, but is it possible the rotor simply isn't spinning?
Could it be a crankshaft position sensor? The wires to the sensor check out but I haven't actually pulled apart the cover to get to the sensor itself.
This may be a stupid question, but is it possible the rotor simply isn't spinning?
#8
09-08-2010, 04:09 PM
Well we did a K Test with the MAP sensor and I read it was supposed to be 5 V but it read 160 mV.
Perform the K-Test on the ECM:
The K-Test: Remove the MAP Sensor connector and turn the ignition switch to ON (Position II). Using a multimeter, check for 5 volts going between the MAP Sensor connector's reference wire (+) and ground. As you look at the connector, this is the socket on the right. Really press the black test lead into a cleaned main ECM ground on the thermostat housing. If the voltage is low, it’s probably indicating ECM failure. Most failed ECMs will record a fraction of a volt. To me, the K-Test is simple, elegant, and accurate.
The K-Test: Remove the MAP Sensor connector and turn the ignition switch to ON (Position II). Using a multimeter, check for 5 volts going between the MAP Sensor connector's reference wire (+) and ground. As you look at the connector, this is the socket on the right. Really press the black test lead into a cleaned main ECM ground on the thermostat housing. If the voltage is low, it’s probably indicating ECM failure. Most failed ECMs will record a fraction of a volt. To me, the K-Test is simple, elegant, and accurate.
#9
09-09-2010, 10:29 AM
So just to recap:
The problem is no spark and no power being supplied to the fuel system (pump or injectors).
-Battery checks out at 12ish V
-Ignition Coil Checks out, as do cap and rotor
-Spark plugs check out
-Crankshaft position sensor continuity test checks out
-All grounding wires (to engine, ECU, ignition etc) check out
-Fuel pump checks out
-Fuel injectors check out
-main relay passes continuity test
-Ignition switch checks out
-There is fuel in the tank and fuel pressure in the injector assembly
-CEL stays on all the time
-K test reveals MAP sensor is under voltage
Is there any other test that I can really do or do I just need to pull the ECM and get a new one?
The problem is no spark and no power being supplied to the fuel system (pump or injectors).
-Battery checks out at 12ish V
-Ignition Coil Checks out, as do cap and rotor
-Spark plugs check out
-Crankshaft position sensor continuity test checks out
-All grounding wires (to engine, ECU, ignition etc) check out
-Fuel pump checks out
-Fuel injectors check out
-main relay passes continuity test
-Ignition switch checks out
-There is fuel in the tank and fuel pressure in the injector assembly
-CEL stays on all the time
-K test reveals MAP sensor is under voltage
Is there any other test that I can really do or do I just need to pull the ECM and get a new one?
#10
09-09-2010, 10:46 AM
Check at the ECU that all the power pins on the ECU are getting power and all the ground pins are grounded. I don't have the diagram with me to tell which ones are which right now.
Unplug the sensors (MAP and TPS) and see if the 5 volts comes back (could be a short in the sensor). Also unplug ECU and make sure no short from the 5 volt wire to ground.
If all that checks out, safe bet to replace the ECU.
Unplug the sensors (MAP and TPS) and see if the 5 volts comes back (could be a short in the sensor). Also unplug ECU and make sure no short from the 5 volt wire to ground.
If all that checks out, safe bet to replace the ECU.