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This topic seems to be coming up, more and more lately... and I am getting a bit bored repating myself - or trying to fin posts where I can point people at. In time I will do this subject more justice with proper diagrams, pretty pictures and whatever.
For now here is a rough and ready version. Oh and I will have to keep it S2/RS2 specific for now - lots of it is directly compatible to the AAN motor, but references to fusebox info and wire colours will not translate so well.
Sudden failures / no start situations will almost certainly be due to an electrical fault, but there is always a chance that something like a slipped timing belt or whatever can cause such problems.
1 - If you have any doubts about the cars security and aftermarket fitments then seek out problems in those areas first. They can be wired in all sorts of wonderful (and stupid) ways to interfere with the starter, fuel pump, coil or ECU wiring.
2 - Sounds stupid, but check all the fuses and robustness of 12V straps around the battery, alternator, starter and ignition switch. Check earth straps to.
3 - If the car does not turn over when you turn the key - then suspect is ignition switch, the starter motor or security. A starter motor fault is commonly the solenoid that activates the main feed. If you hear it clicking, then the solenoid is trying to engage the starter. The battery needs to supply something like 120-200Amps during cold cranking so this is quite a test for old batteries.
4 - If the car spins on the starter then you need to find out which one of the four main things is missing - timing, compression, fuel or spark
4.1 - Check that the alignment marks on the crankshaft pulley (or flywheel via the bellhousing window) and the camshaft pulley are perfectly aligned. Note that an RS2 (ADU engine only) is supposed to be 'one tooth off to the left'. 3B, AAN and ABY teeth should be as per the reference points. On a 3B (or AAN with 'tuna can' dissy) - check that the rotor arm (or sensor) alignment is also visually correct. Hand crank the car to be certain that everything moves as it should.... Remember two crank revolutions to one camshaft rotation.
4.2 - Disconnect the multi-pin plug(s) at the POS units that feed the coil(s). This prevents any chance of a spark. With a compression gauge screwed into each cylinder in turn - spinning the starter with throttle pedal fully depressed - do this for about 4 or 5 rotations and record the cylinder pressure. They should all be approximately the same and all well above ~10bar. Refit spark plugs (after checking them physically) and tighten no more than 25-30Nm. Then reconnect coil power plug(s).
4.3 - The ECU only activates the fuel pump when it thinks the engine is spinning faster than ~25rpm - this is primarily a safety feature that will shut off fuel in a heavy accident. To ascertain if the engine is receiving fuel you really need to split the fuel line at where it enters or leaves the fuel rail. Expect some spillage when working here and do take ALL sensible precaution not to set your face on fire. You likely need a beautiful, charming (and willing) assistant to try and start the car while monitoring the fuel supply. If you see fuel, then the ECU is definitely powered up and definitely seeing the RPM signal from the G28 sensor. Also it verifies that the fuel pump and relay are active. If you wish to test the fuel supply rate then do so safely with a measured container and operate the pump for 15 seconds - you should get well in excess of ~300cc of fuel in that time. One way to TEMPORARILY force fuel pump on is to remove the cover of the relay and close the contacts with insulating tape... refit the cover and plug it back in. This is for TESTS ONLY for obvious reasons.
4.4 The ECU only activates spark when it gets good signals from G4 (crank reference) and G40 (camshaft) sensors at the expected times. A no spark condition is most commonly caused by a fault G40 sensor - sometime pouring cold water on it will get you home. The G4 crank sensor is much more robust but its worth checking that the big lug pin on the flywheel is still in tact - can be seen or felt (carefully) through the bellhouse window. Next source of failure is likely to be in relation to wiring faults. A common one on ABY/AAN is a bad earth from coilpacks to the head.
5 - If the car has 'no fuel' or 'no spark' faults then its wise to check the ECU has good 0V and 12V connections. If you can retrieve fault codes via OBD then its a good sign obviously, but it doesn't tell you everything. Check also that 12V is present at one side of the fuel injectors while the ignition is on - this tells you the ECU is correctly passing power thru an internal relay and that the injector fuse is OK.
6 - Faults in MAF, throttle pot and every other sensor on the engine should not cause a no start condition... If the engine is as follows -
- correctly timed mechanically
- makes good compression (broadly verifies condition of rings, valves and gaskets)
- turns over on the starter faster than ~25rpm (weak batteries may not permit this)
- ECU powered up, earthed and fused correctly (more to come on this one)
- Injectors are receiving nominal 12V supply (key ON)
- Coil or coilpacks are receiving nominal 12V supply (key ON)
- G4, G28 and G40 are wired and working properly
- The fuel pump is good (NOTE - It does NOT prime when you turn the key on)
- There is good fuel in the tank (not 5yr old watered down filth)
- The fuel pump relay is good
- No aftermarket security wiring or hidden switches are messing things up
- Then it simply WILL start... it might run like crap if other sensors are missing
I will add/edit this over time but hopefully it becomes 1st point of reference for all those nasty no-start situations. Feel free to correct any errors or omissions - I have done this off the top of my head basically in about 20mins.
For now here is a rough and ready version. Oh and I will have to keep it S2/RS2 specific for now - lots of it is directly compatible to the AAN motor, but references to fusebox info and wire colours will not translate so well.
Sudden failures / no start situations will almost certainly be due to an electrical fault, but there is always a chance that something like a slipped timing belt or whatever can cause such problems.
1 - If you have any doubts about the cars security and aftermarket fitments then seek out problems in those areas first. They can be wired in all sorts of wonderful (and stupid) ways to interfere with the starter, fuel pump, coil or ECU wiring.
2 - Sounds stupid, but check all the fuses and robustness of 12V straps around the battery, alternator, starter and ignition switch. Check earth straps to.
3 - If the car does not turn over when you turn the key - then suspect is ignition switch, the starter motor or security. A starter motor fault is commonly the solenoid that activates the main feed. If you hear it clicking, then the solenoid is trying to engage the starter. The battery needs to supply something like 120-200Amps during cold cranking so this is quite a test for old batteries.
4 - If the car spins on the starter then you need to find out which one of the four main things is missing - timing, compression, fuel or spark
4.1 - Check that the alignment marks on the crankshaft pulley (or flywheel via the bellhousing window) and the camshaft pulley are perfectly aligned. Note that an RS2 (ADU engine only) is supposed to be 'one tooth off to the left'. 3B, AAN and ABY teeth should be as per the reference points. On a 3B (or AAN with 'tuna can' dissy) - check that the rotor arm (or sensor) alignment is also visually correct. Hand crank the car to be certain that everything moves as it should.... Remember two crank revolutions to one camshaft rotation.
4.2 - Disconnect the multi-pin plug(s) at the POS units that feed the coil(s). This prevents any chance of a spark. With a compression gauge screwed into each cylinder in turn - spinning the starter with throttle pedal fully depressed - do this for about 4 or 5 rotations and record the cylinder pressure. They should all be approximately the same and all well above ~10bar. Refit spark plugs (after checking them physically) and tighten no more than 25-30Nm. Then reconnect coil power plug(s).
4.3 - The ECU only activates the fuel pump when it thinks the engine is spinning faster than ~25rpm - this is primarily a safety feature that will shut off fuel in a heavy accident. To ascertain if the engine is receiving fuel you really need to split the fuel line at where it enters or leaves the fuel rail. Expect some spillage when working here and do take ALL sensible precaution not to set your face on fire. You likely need a beautiful, charming (and willing) assistant to try and start the car while monitoring the fuel supply. If you see fuel, then the ECU is definitely powered up and definitely seeing the RPM signal from the G28 sensor. Also it verifies that the fuel pump and relay are active. If you wish to test the fuel supply rate then do so safely with a measured container and operate the pump for 15 seconds - you should get well in excess of ~300cc of fuel in that time. One way to TEMPORARILY force fuel pump on is to remove the cover of the relay and close the contacts with insulating tape... refit the cover and plug it back in. This is for TESTS ONLY for obvious reasons.
4.4 The ECU only activates spark when it gets good signals from G4 (crank reference) and G40 (camshaft) sensors at the expected times. A no spark condition is most commonly caused by a fault G40 sensor - sometime pouring cold water on it will get you home. The G4 crank sensor is much more robust but its worth checking that the big lug pin on the flywheel is still in tact - can be seen or felt (carefully) through the bellhouse window. Next source of failure is likely to be in relation to wiring faults. A common one on ABY/AAN is a bad earth from coilpacks to the head.
5 - If the car has 'no fuel' or 'no spark' faults then its wise to check the ECU has good 0V and 12V connections. If you can retrieve fault codes via OBD then its a good sign obviously, but it doesn't tell you everything. Check also that 12V is present at one side of the fuel injectors while the ignition is on - this tells you the ECU is correctly passing power thru an internal relay and that the injector fuse is OK.
6 - Faults in MAF, throttle pot and every other sensor on the engine should not cause a no start condition... If the engine is as follows -
- correctly timed mechanically
- makes good compression (broadly verifies condition of rings, valves and gaskets)
- turns over on the starter faster than ~25rpm (weak batteries may not permit this)
- ECU powered up, earthed and fused correctly (more to come on this one)
- Injectors are receiving nominal 12V supply (key ON)
- Coil or coilpacks are receiving nominal 12V supply (key ON)
- G4, G28 and G40 are wired and working properly
- The fuel pump is good (NOTE - It does NOT prime when you turn the key on)
- There is good fuel in the tank (not 5yr old watered down filth)
- The fuel pump relay is good
- No aftermarket security wiring or hidden switches are messing things up
- Then it simply WILL start... it might run like crap if other sensors are missing
I will add/edit this over time but hopefully it becomes 1st point of reference for all those nasty no-start situations. Feel free to correct any errors or omissions - I have done this off the top of my head basically in about 20mins.
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