HELP PLEASE!!!Car turns over but won't start
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10-10-2010, 03:54 AM
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HELP PLEASE!!!Car turns over but won't start
I had my engine replaced and when it was put in, it ran rough for like a min then shut off.Now all the car does is turn over but wont start, brought it to Nissan and it's not throwing any codes, they checked the flywheel, and they cant seem to figure out why its not starting.They say its not getting any spark, could the ECM be bad or could it be a cam sensor, or something else Nissan/me are missing??? Please if anyone knows what could be wrong let me know asap...thank you
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10-10-2010, 04:55 AM
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10-10-2010, 06:05 AM
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10-10-2010, 07:16 AM
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I had this happen on my old Volvo a couple of times, so I learned to follow a linear process of elimination that likely applies here-- an engine needs 4 basic things to start:
1) sufficient cranking speed,
2) good compression,
3) adequate ignition voltage (with correct timing), and
4) fuel (a relatively rich air/fuel mixture initially).
90% of the time it's one of these. A non-functioning MAF sensor I think will allow your engine to work, but it will be rough, it did on my car.
Now comes the linear process of elimination, we know it cranks so we can eliminate that process (unless the cranking is too slow, at which point you'd begin looking at the battery).
Move next to ignition, fuel or compression issues. If it ran before, begin looking at the fuel pump, ignition module or timing of overhead crank. Ignition is easy to check with a spark tester or just position a plug wire near a good ground. No spark? Now you know where to take your focus.
If the module isn't working, most of the time it's broken, corroded or has loose terminals. If these all look fine, but still you're not getting the output, look at the the crankshaft position sensor, check the sensor's reference voltage (VRef) and ground (I'm not sure how this works on our cars). The sensor must have ~5 volts (I think) or it will remain permanently off and not generate a crank signal (which should set a fault code). I don't know how much you know about cars, so I'll leave it at that for now and if you have more questions, write in.
If the engine turns and you have spark, check for fuel-- is the fuel pump working? Are the lines clear? Was it properly connected? Is there pressure on the lines? If the answer is no to pressure when the key is on, check for a failed fuel pump, pump relay, fuse or wiring problem. Sometimes something as simple as really bad gas can cause you car to not start or ride extremely rough and finally shut down.
Forgot to mention, are the injectors all working? Do you hear that clicking or buzzing sound from all of them? A defective ECU may not be driving the injectors, or the EFI power supply relay may have turned belly up. Some EFI-systems rely on input from the camshaft position sensor to generate the injector pulses (not sure if this is how it works for our cars, maybe someone else can better answer this one). Loss of this signal could prevent the system from functioning.
With all that being said, something as simple as a massive vacuum leak can keep the engine from starting-- it can lean out the air/fuel ratio to such an extent that the mixture won't ignite. An EGR valve that is stuck on open, a disconnected PCV hose, loose vacuum hose for the power brake booster, or similar leak could be the culprit. Check all vacuum connections and listen for unusual sucking or whistling noises while cranking.
An engine that has fuel and spark, no serious vacuum leaks and cranks normally should start, if not, move to compression issues, although this seems unlikely since your engine was just changed and I'd assume that the timing chain was working well.
There are so many variables, but all I did was just walk you thru my very crude process of elimination steps. These steps work with my ancient Volvo, but I'm not sure how effective they would be on the G. The engineering is identical, the fine tuning and electronics is not so much so.
Good luck and I hope this helps.
PS: Just realized you've had it seen by the Nissan tech, so I might just be repeating the steps he/she will follow.
1) sufficient cranking speed,
2) good compression,
3) adequate ignition voltage (with correct timing), and
4) fuel (a relatively rich air/fuel mixture initially).
90% of the time it's one of these. A non-functioning MAF sensor I think will allow your engine to work, but it will be rough, it did on my car.
Now comes the linear process of elimination, we know it cranks so we can eliminate that process (unless the cranking is too slow, at which point you'd begin looking at the battery).
Move next to ignition, fuel or compression issues. If it ran before, begin looking at the fuel pump, ignition module or timing of overhead crank. Ignition is easy to check with a spark tester or just position a plug wire near a good ground. No spark? Now you know where to take your focus.
If the module isn't working, most of the time it's broken, corroded or has loose terminals. If these all look fine, but still you're not getting the output, look at the the crankshaft position sensor, check the sensor's reference voltage (VRef) and ground (I'm not sure how this works on our cars). The sensor must have ~5 volts (I think) or it will remain permanently off and not generate a crank signal (which should set a fault code). I don't know how much you know about cars, so I'll leave it at that for now and if you have more questions, write in.
If the engine turns and you have spark, check for fuel-- is the fuel pump working? Are the lines clear? Was it properly connected? Is there pressure on the lines? If the answer is no to pressure when the key is on, check for a failed fuel pump, pump relay, fuse or wiring problem. Sometimes something as simple as really bad gas can cause you car to not start or ride extremely rough and finally shut down.
Forgot to mention, are the injectors all working? Do you hear that clicking or buzzing sound from all of them? A defective ECU may not be driving the injectors, or the EFI power supply relay may have turned belly up. Some EFI-systems rely on input from the camshaft position sensor to generate the injector pulses (not sure if this is how it works for our cars, maybe someone else can better answer this one). Loss of this signal could prevent the system from functioning.
With all that being said, something as simple as a massive vacuum leak can keep the engine from starting-- it can lean out the air/fuel ratio to such an extent that the mixture won't ignite. An EGR valve that is stuck on open, a disconnected PCV hose, loose vacuum hose for the power brake booster, or similar leak could be the culprit. Check all vacuum connections and listen for unusual sucking or whistling noises while cranking.
An engine that has fuel and spark, no serious vacuum leaks and cranks normally should start, if not, move to compression issues, although this seems unlikely since your engine was just changed and I'd assume that the timing chain was working well.
There are so many variables, but all I did was just walk you thru my very crude process of elimination steps. These steps work with my ancient Volvo, but I'm not sure how effective they would be on the G. The engineering is identical, the fine tuning and electronics is not so much so.
Good luck and I hope this helps.
PS: Just realized you've had it seen by the Nissan tech, so I might just be repeating the steps he/she will follow.
#5
10-10-2010, 08:18 AM
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thank you so much for your help, nissan seems to thinks its either one of the cam sensors or the ECM is bad..a friend of mine has an 05 sedan that he is letting them take apart so they can try all the cam sensors to see if 1 or more is bad.they said that its not getting spark and no injector pulse, so I hope they can figure it out soon.I have been without my car for almost 2 months now,nobody seems to be able to figure out whats wrong with it 
I had this happen on my old Volvo a couple of times, so I learned to follow a linear process of elimination that likely applies here-- an engine needs 4 basic things to start:
1) sufficient cranking speed,
2) good compression,
3) adequate ignition voltage (with correct timing), and
4) fuel (a relatively rich air/fuel mixture initially).
90% of the time it's one of these. A non-functioning MAF sensor I think will allow your engine to work, but it will be rough, it did on my car.
Now comes the linear process of elimination, we know it cranks so we can eliminate that process (unless the cranking is too slow, at which point you'd begin looking at the battery).
Move next to ignition, fuel or compression issues. If it ran before, begin looking at the fuel pump, ignition module or timing of overhead crank. Ignition is easy to check with a spark tester or just position a plug wire near a good ground. No spark? Now you know where to take your focus.
If the module isn't working, most of the time it's broken, corroded or has loose terminals. If these all look fine, but still you're not getting the output, look at the the crankshaft position sensor, check the sensor's reference voltage (VRef) and ground (I'm not sure how this works on our cars). The sensor must have ~5 volts (I think) or it will remain permanently off and not generate a crank signal (which should set a fault code). I don't know how much you know about cars, so I'll leave it at that for now and if you have more questions, write in.
If the engine turns and you have spark, check for fuel-- is the fuel pump working? Are the lines clear? Was it properly connected? Is there pressure on the lines? If the answer is no to pressure when the key is on, check for a failed fuel pump, pump relay, fuse or wiring problem. Sometimes something as simple as really bad gas can cause you car to not start or ride extremely rough and finally shut down.
Forgot to mention, are the injectors all working? Do you hear that clicking or buzzing sound from all of them? A defective ECU may not be driving the injectors, or the EFI power supply relay may have turned belly up. Some EFI-systems rely on input from the camshaft position sensor to generate the injector pulses (not sure if this is how it works for our cars, maybe someone else can better answer this one). Loss of this signal could prevent the system from functioning.
With all that being said, something as simple as a massive vacuum leak can keep the engine from starting-- it can lean out the air/fuel ratio to such an extent that the mixture won't ignite. An EGR valve that is stuck on open, a disconnected PCV hose, loose vacuum hose for the power brake booster, or similar leak could be the culprit. Check all vacuum connections and listen for unusual sucking or whistling noises while cranking.
An engine that has fuel and spark, no serious vacuum leaks and cranks normally should start, if not, move to compression issues, although this seems unlikely since your engine was just changed and I'd assume that the timing chain was working well.
There are so many variables, but all I did was just walk you thru my very crude process of elimination steps. These steps work with my ancient Volvo, but I'm not sure how effective they would be on the G. The engineering is identical, the fine tuning and electronics is not so much so.
Good luck and I hope this helps.
PS: Just realized you've had it seen by the Nissan tech, so I might just be repeating the steps he/she will follow.
1) sufficient cranking speed,
2) good compression,
3) adequate ignition voltage (with correct timing), and
4) fuel (a relatively rich air/fuel mixture initially).
90% of the time it's one of these. A non-functioning MAF sensor I think will allow your engine to work, but it will be rough, it did on my car.
Now comes the linear process of elimination, we know it cranks so we can eliminate that process (unless the cranking is too slow, at which point you'd begin looking at the battery).
Move next to ignition, fuel or compression issues. If it ran before, begin looking at the fuel pump, ignition module or timing of overhead crank. Ignition is easy to check with a spark tester or just position a plug wire near a good ground. No spark? Now you know where to take your focus.
If the module isn't working, most of the time it's broken, corroded or has loose terminals. If these all look fine, but still you're not getting the output, look at the the crankshaft position sensor, check the sensor's reference voltage (VRef) and ground (I'm not sure how this works on our cars). The sensor must have ~5 volts (I think) or it will remain permanently off and not generate a crank signal (which should set a fault code). I don't know how much you know about cars, so I'll leave it at that for now and if you have more questions, write in.
If the engine turns and you have spark, check for fuel-- is the fuel pump working? Are the lines clear? Was it properly connected? Is there pressure on the lines? If the answer is no to pressure when the key is on, check for a failed fuel pump, pump relay, fuse or wiring problem. Sometimes something as simple as really bad gas can cause you car to not start or ride extremely rough and finally shut down.
Forgot to mention, are the injectors all working? Do you hear that clicking or buzzing sound from all of them? A defective ECU may not be driving the injectors, or the EFI power supply relay may have turned belly up. Some EFI-systems rely on input from the camshaft position sensor to generate the injector pulses (not sure if this is how it works for our cars, maybe someone else can better answer this one). Loss of this signal could prevent the system from functioning.
With all that being said, something as simple as a massive vacuum leak can keep the engine from starting-- it can lean out the air/fuel ratio to such an extent that the mixture won't ignite. An EGR valve that is stuck on open, a disconnected PCV hose, loose vacuum hose for the power brake booster, or similar leak could be the culprit. Check all vacuum connections and listen for unusual sucking or whistling noises while cranking.
An engine that has fuel and spark, no serious vacuum leaks and cranks normally should start, if not, move to compression issues, although this seems unlikely since your engine was just changed and I'd assume that the timing chain was working well.
There are so many variables, but all I did was just walk you thru my very crude process of elimination steps. These steps work with my ancient Volvo, but I'm not sure how effective they would be on the G. The engineering is identical, the fine tuning and electronics is not so much so.
Good luck and I hope this helps.
PS: Just realized you've had it seen by the Nissan tech, so I might just be repeating the steps he/she will follow.
#7
10-10-2010, 03:20 PM
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#8
12-09-2010, 05:18 PM
Did you ever sort this problem? I have the same sort of problem.
I can get my car to run on Aerostart. I can manually run my injectors and the car runs.
It seems as though everything is running bar the injector pulse....this has got me stumped.....I have spend the last 7 day's checking every possible cause!
Any help would be awesome.
I can get my car to run on Aerostart. I can manually run my injectors and the car runs.
It seems as though everything is running bar the injector pulse....this has got me stumped.....I have spend the last 7 day's checking every possible cause!
Any help would be awesome.
#12
12-09-2010, 06:06 PM
#13
12-09-2010, 06:11 PM
oh nice mate. haha i`ve met a lot of chill australian gamers on xbox live haha always get a good laugh session when we trash talk to the other team 
haha but nice. i think you are the first G owner I have seen on this forum.
and thats true man. haha i need my life back too so i have not even touched cod or halo for an entire month since i want to get my car looking sexy now
haha but nice. i think you are the first G owner I have seen on this forum.and thats true man. haha i need my life back too so i have not even touched cod or halo for an entire month since i want to get my car looking sexy now
#14
12-09-2010, 08:06 PM
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Did you ever sort this problem? I have the same sort of problem.
I can get my car to run on Aerostart. I can manually run my injectors and the car runs.
It seems as though everything is running bar the injector pulse....this has got me stumped.....I have spend the last 7 day's checking every possible cause!
Any help would be awesome.
I can get my car to run on Aerostart. I can manually run my injectors and the car runs.
It seems as though everything is running bar the injector pulse....this has got me stumped.....I have spend the last 7 day's checking every possible cause!
Any help would be awesome.
