Strange problem!!
02-08-2014, 11:47 AM
#1
Staging Lane
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Strange problem!! Hi there,
I am having this strange problem with my 2002 WS6.
Every couple of weeks the engine doesn't fire up although it starts. I have to try many times ( maybe 5-6 times insides 2-3 minutes) then it will fire up. It doesn't happen at a particular time, could happen in the morning or night. Didn't notice any specific pattern and could happen when engine is hot or cold.
As I said, it doesnt happen always, just once in a couple of weeks.
The car has 24K miles, M6. Has kooks full exhaust with headers and cold air intake, rest is stock.
What should I check? fuel filter or pump? spark plugs?
I am having this strange problem with my 2002 WS6.
Every couple of weeks the engine doesn't fire up although it starts. I have to try many times ( maybe 5-6 times insides 2-3 minutes) then it will fire up. It doesn't happen at a particular time, could happen in the morning or night. Didn't notice any specific pattern and could happen when engine is hot or cold.
As I said, it doesnt happen always, just once in a couple of weeks.
The car has 24K miles, M6. Has kooks full exhaust with headers and cold air intake, rest is stock.
What should I check? fuel filter or pump? spark plugs?
02-08-2014, 02:24 PM
#4
the fuel filter almost never causes a problem. if your fuel filter were clogged and restricting fuel then you would most certainly notice it when the engine is running higher rpm under load when it requires the most fuel. and before starting the engine when the fuel pump primes, there is very little to zero fuel flow to pressurize the lines up to the injectors, so even the most restrictive fuel filter will still let enough by to get the system up to 50 psi and then allow the engine to start and idle.
for your intermittent no start problem if you have no other problems once the engine is running, can be quite difficult.
my recommendation since it's an intermittent problem is to put a fuel pressure gauge on the injector rail and monitor pressure each time you turn the key to run and the fuel pump primes the system then until the engine starts. and you might also want to leave the gauge on there once the car is off as it sits over a day to see if the fuel system loses pressure- that "could" be a sign of a failing fuel pump. so try and catch fuel pressure when the problem happens and go from there. this will rule out it being a fuel problem. the other thing would be checking if the ignition coils are putting out when your problem happens, how you might be able to check that easily i'm not sure.
with only 24k miles, it's not your spark plugs unless you cracked many of them or have burnt plug wires because you have headers, and then you would have problems when the engine is running and under load which you did not mention.
a no start condition like you describe makes me think possibly crank position sensor or wiring problem.
and, is your battery healty? when the engine cranks and doesn't start is it cranking fast or does it start cranking slowly after the first couple tries because of a weak battery?
for your intermittent no start problem if you have no other problems once the engine is running, can be quite difficult.
my recommendation since it's an intermittent problem is to put a fuel pressure gauge on the injector rail and monitor pressure each time you turn the key to run and the fuel pump primes the system then until the engine starts. and you might also want to leave the gauge on there once the car is off as it sits over a day to see if the fuel system loses pressure- that "could" be a sign of a failing fuel pump. so try and catch fuel pressure when the problem happens and go from there. this will rule out it being a fuel problem. the other thing would be checking if the ignition coils are putting out when your problem happens, how you might be able to check that easily i'm not sure.
with only 24k miles, it's not your spark plugs unless you cracked many of them or have burnt plug wires because you have headers, and then you would have problems when the engine is running and under load which you did not mention.
a no start condition like you describe makes me think possibly crank position sensor or wiring problem.
and, is your battery healty? when the engine cranks and doesn't start is it cranking fast or does it start cranking slowly after the first couple tries because of a weak battery?
02-08-2014, 08:44 PM
#5
Staging Lane
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the fuel filter almost never causes a problem. if your fuel filter were clogged and restricting fuel then you would most certainly notice it when the engine is running higher rpm under load when it requires the most fuel. and before starting the engine when the fuel pump primes, there is very little to zero fuel flow to pressurize the lines up to the injectors, so even the most restrictive fuel filter will still let enough by to get the system up to 50 psi and then allow the engine to start and idle.
for your intermittent no start problem if you have no other problems once the engine is running, can be quite difficult.
my recommendation since it's an intermittent problem is to put a fuel pressure gauge on the injector rail and monitor pressure each time you turn the key to run and the fuel pump primes the system then until the engine starts. and you might also want to leave the gauge on there once the car is off as it sits over a day to see if the fuel system loses pressure- that "could" be a sign of a failing fuel pump. so try and catch fuel pressure when the problem happens and go from there. this will rule out it being a fuel problem. the other thing would be checking if the ignition coils are putting out when your problem happens, how you might be able to check that easily i'm not sure.
with only 24k miles, it's not your spark plugs unless you cracked many of them or have burnt plug wires because you have headers, and then you would have problems when the engine is running and under load which you did not mention.
a no start condition like you describe makes me think possibly crank position sensor or wiring problem.
and, is your battery healty? when the engine cranks and doesn't start is it cranking fast or does it start cranking slowly after the first couple tries because of a weak battery?
for your intermittent no start problem if you have no other problems once the engine is running, can be quite difficult.
my recommendation since it's an intermittent problem is to put a fuel pressure gauge on the injector rail and monitor pressure each time you turn the key to run and the fuel pump primes the system then until the engine starts. and you might also want to leave the gauge on there once the car is off as it sits over a day to see if the fuel system loses pressure- that "could" be a sign of a failing fuel pump. so try and catch fuel pressure when the problem happens and go from there. this will rule out it being a fuel problem. the other thing would be checking if the ignition coils are putting out when your problem happens, how you might be able to check that easily i'm not sure.
with only 24k miles, it's not your spark plugs unless you cracked many of them or have burnt plug wires because you have headers, and then you would have problems when the engine is running and under load which you did not mention.
a no start condition like you describe makes me think possibly crank position sensor or wiring problem.
and, is your battery healty? when the engine cranks and doesn't start is it cranking fast or does it start cranking slowly after the first couple tries because of a weak battery?
I scanned the ECM and it returned code 0419 or 0420 I guess something which said oxygen sensors or something can't remember ( or was it catalyc converter...) so I deleted the codes but they come back every few days.
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03-01-2014, 08:25 PM
#10
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Have you given it a general tune up?
Plugs, wires, ignition module?
Check fuel pressure as stated and check for codes.
First try this: cycle the key 3 times and then crank. Does it start like that?
If so its probably the fuel pump or check valve.
If not then check fuel press. If that checks good the replace the spark plugs and might as well put a new air filter in if necessary.
Might want to try cleaning the IAC also.
Plugs, wires, ignition module?
Check fuel pressure as stated and check for codes.
First try this: cycle the key 3 times and then crank. Does it start like that?
If so its probably the fuel pump or check valve.
If not then check fuel press. If that checks good the replace the spark plugs and might as well put a new air filter in if necessary.
Might want to try cleaning the IAC also.
03-01-2014, 10:44 PM
#11
Staging Lane
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Have you given it a general tune up?
Plugs, wires, ignition module?
Check fuel pressure as stated and check for codes.
First try this: cycle the key 3 times and then crank. Does it start like that?
If so its probably the fuel pump or check valve.
If not then check fuel press. If that checks good the replace the spark plugs and might as well put a new air filter in if necessary.
Might want to try cleaning the IAC also.
Plugs, wires, ignition module?
Check fuel pressure as stated and check for codes.
First try this: cycle the key 3 times and then crank. Does it start like that?
If so its probably the fuel pump or check valve.
If not then check fuel press. If that checks good the replace the spark plugs and might as well put a new air filter in if necessary.
Might want to try cleaning the IAC also.
I am also suspecting the fuel pump coz I had a similar issue on my 2001 Z28 and it turned out to be the fuel pump.
03-01-2014, 11:01 PM
#12
Staging Lane
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Have you given it a general tune up?
Plugs, wires, ignition module?
Check fuel pressure as stated and check for codes.
First try this: cycle the key 3 times and then crank. Does it start like that?
If so its probably the fuel pump or check valve.
If not then check fuel press. If that checks good the replace the spark plugs and might as well put a new air filter in if necessary.
Might want to try cleaning the IAC also.
Plugs, wires, ignition module?
Check fuel pressure as stated and check for codes.
First try this: cycle the key 3 times and then crank. Does it start like that?
If so its probably the fuel pump or check valve.
If not then check fuel press. If that checks good the replace the spark plugs and might as well put a new air filter in if necessary.
Might want to try cleaning the IAC also.
If the engine is hot of if there is no big time gap between starts it works from the first try, otherwise if I park it at night and turn in on next morning it doesnt start.
03-04-2014, 01:53 PM
#15
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You need to start by checking fuel pressure with a gauge after it primes but before you attempt to start it. It should be at least 50 psi to get it to start. As was mentioned before, I have never seen a fuel filter cause issues with starting. The fuel pump would be the starting issue.
When I had my intermittent no start issues, I suspected it was the fuel pump as well, but I was wrong. It ended up being the ignition relay. The symptoms are slightly different though. With a bad fuel pump, it might struggle to fire but eventually start. With the bad ignition relay, it would just turn over and not even come close to sounding like it was going to start. Hope this helps.
When I had my intermittent no start issues, I suspected it was the fuel pump as well, but I was wrong. It ended up being the ignition relay. The symptoms are slightly different though. With a bad fuel pump, it might struggle to fire but eventually start. With the bad ignition relay, it would just turn over and not even come close to sounding like it was going to start. Hope this helps.
06-18-2014, 11:51 PM
#18
Staging Lane
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So my mechanic says fuel supply is fine, fuel pump, lines, etc.. and he is suspecting an electrical issue that is preventing the engine to run.
He says he is suspecting the crank sensor or the cam sensor.
Shall I go ahead and replace both?
Just to remind you people of my issue. Every now and then my engine cranks but doesn't run. I have to crank many times - 5-6 times for it to run and once it runs it runs just fine.
I replaced fuel filter, spark plugs and cleaned up the injectors.
He says he is suspecting the crank sensor or the cam sensor.
Shall I go ahead and replace both?
Just to remind you people of my issue. Every now and then my engine cranks but doesn't run. I have to crank many times - 5-6 times for it to run and once it runs it runs just fine.
I replaced fuel filter, spark plugs and cleaned up the injectors.
06-19-2014, 07:16 PM
#19
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How many keys do you have on your key chain? I've seen this so many times. To much weight and it wears out ignitions. Just a though. Dad had a similar problem with his 06 silverado and it ended up being a bad connection with his bcm.
06-20-2014, 03:13 PM
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But it could be BOTH, and the crank position sensor is a quick/easy change as only the starter has to be dropped, or moved to get to it.
