ATW Engine No Start. Has Fuel, Has Spark.
#1
11-05-2016, 11:43 AM
ATW Engine No Start. Has Fuel, Has Spark.
So I went to go pick up my friend a few days ago, it's only about a mile drive. The car started fine and didn't hesitate to turn over. On the way over there was nothing abnormal going on either. Pulled in the driveway and after saaay a minute of idling the car just turned off. Tried turning it back over and nothing, just cranks and cranks. Flat towed it back to my house and tore into it.
Scanned the car once i got home and the only code coming back was a throttle body malfunction. I thought this couldn't be it because you can hear it doing its self alignment when you turn the key on. Went to the local scrap yard and got a new TB anyways. Plug everything in and still the same codes. Moved onto the next part in question.
Tested fuel pressure but my dial only went to 80lb and it was maxed out. Thought fuel was fine. Can anyone tell me what the pump primes at, pressure wise?
Moved onto the timing. Belt is in good condition and timing marks line up with piston 1 at TDC.
Moved onto spark. This is one thing that confused me. I bought the replacement set of coils from ECS on August 1st and I still had my old coils, I pulled the plug to look at the spark. On the new coil there was hardly an arc. Put old coil on that plug and you could see the spark easily! Could a bad batch of coils cause a no start without throwing any codes?
Can someone help me out with any advise on what to look for next? It's driving me crazy not knowing what could be wrong.
Scanned the car once i got home and the only code coming back was a throttle body malfunction. I thought this couldn't be it because you can hear it doing its self alignment when you turn the key on. Went to the local scrap yard and got a new TB anyways. Plug everything in and still the same codes. Moved onto the next part in question.
Tested fuel pressure but my dial only went to 80lb and it was maxed out. Thought fuel was fine. Can anyone tell me what the pump primes at, pressure wise?
Moved onto the timing. Belt is in good condition and timing marks line up with piston 1 at TDC.
Moved onto spark. This is one thing that confused me. I bought the replacement set of coils from ECS on August 1st and I still had my old coils, I pulled the plug to look at the spark. On the new coil there was hardly an arc. Put old coil on that plug and you could see the spark easily! Could a bad batch of coils cause a no start without throwing any codes?
Can someone help me out with any advise on what to look for next? It's driving me crazy not knowing what could be wrong.
#2
11-07-2016, 02:10 PM
The pump's ability to generate pressure is sort-of irrelevant to the pressure you would see when properly measuring fuel pressure... proper measuring location is near the feed line of the fuel rail, right before the fuel rail.
The FPR (fuel pressure regulator) is a rising-rate style rated at 4bar, meaning that the fuel pressure you see is dependent on the intake manifold pressure the FPR sees at its nipple.
So at ambient pressure (i.e. engine off or vacuum line disconnected) the FPR will output 4bar fuel pressure (58 psi). With the engine running and operating at normal vacuum [20 in.Hg], fuel pressure should be ~48psi. And at stock full boost of 8psi, fuel pressure should be ~66psi.
The FPR should be bleeding off any excess pressure, though I'm not sure how this behavior varies with the engine off.
Did you happen to try swapping in you old coils?
Have you tried starting the engine with the MAF unplugged?
One potential is the CTS [coolant temperature sensor]. This is a common one. It's located in the coolant flange at the back of the cylinder head. You can check that it's reporting an accurate engine coolant temperature value using an OBD2 reader or VCDS. With the engine "cold", the reported value should be near ambient temperature.
Only other thing I can think of is crank position sensor, which is near the oil filter. If you're getting spark at all then the CPS is probably okay... best way to verify CPS functionality is to look at engine speed while cranking via an OBD2 reader or VCDS; it should show ~200 RPM while cranking. If you don't see any engine speed value, then replacing the CPS could be a good move.
The FPR (fuel pressure regulator) is a rising-rate style rated at 4bar, meaning that the fuel pressure you see is dependent on the intake manifold pressure the FPR sees at its nipple.
So at ambient pressure (i.e. engine off or vacuum line disconnected) the FPR will output 4bar fuel pressure (58 psi). With the engine running and operating at normal vacuum [20 in.Hg], fuel pressure should be ~48psi. And at stock full boost of 8psi, fuel pressure should be ~66psi.
The FPR should be bleeding off any excess pressure, though I'm not sure how this behavior varies with the engine off.
Did you happen to try swapping in you old coils?
Have you tried starting the engine with the MAF unplugged?
One potential is the CTS [coolant temperature sensor]. This is a common one. It's located in the coolant flange at the back of the cylinder head. You can check that it's reporting an accurate engine coolant temperature value using an OBD2 reader or VCDS. With the engine "cold", the reported value should be near ambient temperature.
Only other thing I can think of is crank position sensor, which is near the oil filter. If you're getting spark at all then the CPS is probably okay... best way to verify CPS functionality is to look at engine speed while cranking via an OBD2 reader or VCDS; it should show ~200 RPM while cranking. If you don't see any engine speed value, then replacing the CPS could be a good move.
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