Nissan QQ J10 2.0 Petrol. Starting/running issues?
Discussion
Hi Guys,
My QQ J10 petrol has developed an issue where it is very difficult to start and then runs rough like it misfiring even on idle and sometimes conks out. Runs really rough when driving. It indeed has code P0300 which indicates random or multiple cylinder misfire.
Tested cylinder compression and that is fine (had a top end rebuild a few months ago)
Tested all coil packs and they are ok.
Tested plugs and on inspection these were quite black and tips worn. I replaced them with new.
Tested injectors and found one of them was giving way to much fuel so replaced. (This is probs what caused me to have to get the top end rebuilt due to burnt valves).
Tested - fuel getting to injectors and seems ok but have noticed that when I open the tank cap I'm now not hearing the rush of air that I used to get which may or may not be related as fuel seems to be pumping to injectors ok.
I'm now stuck as can only imagine that it's either fuel pressure (but injectors seem to fire ok and spray patterns look ok) or air mix somewhere due to the plugs getting blackened. Having said that they could have still been black from before engine top end was rebuilt.
Would fuel pressure or say O2 sensor throw an error code other than P0300?
Any ideas what's going on and what and how to test any remaining possibilities e.,g O2 or fuel pressure etc?
My QQ J10 petrol has developed an issue where it is very difficult to start and then runs rough like it misfiring even on idle and sometimes conks out. Runs really rough when driving. It indeed has code P0300 which indicates random or multiple cylinder misfire.
Tested cylinder compression and that is fine (had a top end rebuild a few months ago)
Tested all coil packs and they are ok.
Tested plugs and on inspection these were quite black and tips worn. I replaced them with new.
Tested injectors and found one of them was giving way to much fuel so replaced. (This is probs what caused me to have to get the top end rebuilt due to burnt valves).
Tested - fuel getting to injectors and seems ok but have noticed that when I open the tank cap I'm now not hearing the rush of air that I used to get which may or may not be related as fuel seems to be pumping to injectors ok.
I'm now stuck as can only imagine that it's either fuel pressure (but injectors seem to fire ok and spray patterns look ok) or air mix somewhere due to the plugs getting blackened. Having said that they could have still been black from before engine top end was rebuilt.
Would fuel pressure or say O2 sensor throw an error code other than P0300?
Any ideas what's going on and what and how to test any remaining possibilities e.,g O2 or fuel pressure etc?
My initial fault a few months back was no compression on Cylinder 2. Had top end rebuilt as valves were apparently burnt/melted. Since the rebuild I had no top end power e.g. I was struggling to say reach 80mph on flat or up slight hill and was loosing speed going up slight hills on Motorway. Seemed ok and punchy at normal road speeds.
Garage took another look but said compression was now fine and that they would need to investigate further at a later date.
Things got progressively worse. I tested compression myself and as they said it seems ok now. Tested injectors by placing them in bottles and cranking engine. Inector that was in 2 was jetting in way more fuel than the others so changed that out and now all four seem to be even and spray pattern looks ok. Tested for spark on all plugs and seems ok but plugs were dirty so just changed them to be sure. Tested coils by following the procedure where you have the coil with spark plug 15mm away from ground and if spark jumps this 15mm then deemed ok. This test was successful.
Code before all work was P0302 and P0300 but now just reports P0300.
Garage took another look but said compression was now fine and that they would need to investigate further at a later date.
Things got progressively worse. I tested compression myself and as they said it seems ok now. Tested injectors by placing them in bottles and cranking engine. Inector that was in 2 was jetting in way more fuel than the others so changed that out and now all four seem to be even and spray pattern looks ok. Tested for spark on all plugs and seems ok but plugs were dirty so just changed them to be sure. Tested coils by following the procedure where you have the coil with spark plug 15mm away from ground and if spark jumps this 15mm then deemed ok. This test was successful.
Code before all work was P0302 and P0300 but now just reports P0300.
Suspect coil/plug issues and/or test.
A plug will spark easier under that test than under internal engine and compression issues.
Try and identify the fault with live data to a single cylinder, or multiples. If single, try swapping coil/plug to different cylinder and see if the fault moves or stays. Or via the parts cannon method (assuming it is a single coil per cylinder), try a new coil and plug in 1 cylinder at a time. Keep moving it to all cylinders in logical method. If either of those methods fail then it is internal engine problem.
A plug will spark easier under that test than under internal engine and compression issues.
Try and identify the fault with live data to a single cylinder, or multiples. If single, try swapping coil/plug to different cylinder and see if the fault moves or stays. Or via the parts cannon method (assuming it is a single coil per cylinder), try a new coil and plug in 1 cylinder at a time. Keep moving it to all cylinders in logical method. If either of those methods fail then it is internal engine problem.
Edited by Coilspring on Monday 22 April 12:40
Hi again,
The test procedure that I used for the coils which are individual is the way that the Nissan tech manual states for testing coils. It states to place the spark plug in the coil and then to position it at an angle between 13-17mm away from ground and that if the spark jumps that gap then coil is good and strong. I do accept that there are different ways of testing but unless all four coils are bad then the ECM would normally report which cyclinder is bad which initially it did and it was no 2 due to no compression.
Garage rebuilt top end (don't know how well) and compression seems ok now as both them and I have retested independently and all cylinders now have compression and its within 15psi of each other.
Car seemed to run ok after the rebuild but still didn't have full power as explained above and further investigations were to happen early next month. The trouble is that last week things took a drastic turn for the worse and with the P0300 code and now engine really struggles to start and then is running really rough like it misfiring but no cylinder code is coming up just the P0300 which I'm told and have read could be a myriad of things.
Tests revealed one bad injector which I have now replaced as well as plugs and coils but still same. Don't know if it's an air issue or fuel or something else as no air/o2 codes are coming up. I am fairly sure I have eliminated coils, plugs and injectors along with compression and can see fuel getting to injectors so apart from air mix or possible weak fuel pressure issue I'm really stuck as to what the hell it could be.
If I somehow had air getting into exhaust system near the O2 sensor which I've yet to check, could that cause really rough idle and drive? could the ECM be mixing fuel to air incorrectly?
Is it possible to have good cylinder compression yet still have top end issues?
The test procedure that I used for the coils which are individual is the way that the Nissan tech manual states for testing coils. It states to place the spark plug in the coil and then to position it at an angle between 13-17mm away from ground and that if the spark jumps that gap then coil is good and strong. I do accept that there are different ways of testing but unless all four coils are bad then the ECM would normally report which cyclinder is bad which initially it did and it was no 2 due to no compression.
Garage rebuilt top end (don't know how well) and compression seems ok now as both them and I have retested independently and all cylinders now have compression and its within 15psi of each other.
Car seemed to run ok after the rebuild but still didn't have full power as explained above and further investigations were to happen early next month. The trouble is that last week things took a drastic turn for the worse and with the P0300 code and now engine really struggles to start and then is running really rough like it misfiring but no cylinder code is coming up just the P0300 which I'm told and have read could be a myriad of things.
Tests revealed one bad injector which I have now replaced as well as plugs and coils but still same. Don't know if it's an air issue or fuel or something else as no air/o2 codes are coming up. I am fairly sure I have eliminated coils, plugs and injectors along with compression and can see fuel getting to injectors so apart from air mix or possible weak fuel pressure issue I'm really stuck as to what the hell it could be.
If I somehow had air getting into exhaust system near the O2 sensor which I've yet to check, could that cause really rough idle and drive? could the ECM be mixing fuel to air incorrectly?
Is it possible to have good cylinder compression yet still have top end issues?
Fractals said:
Hi again,
The test procedure that I used for the coils which are individual is the way that the Nissan tech manual states for testing coils. It states to place the spark plug in the coil and then to position it at an angle between 13-17mm away from ground and that if the spark jumps that gap then coil is good and strong. I do accept that there are different ways of testing but unless all four coils are bad then the ECM would normally report which cyclinder is bad which initially it did and it was no 2 due to no compression.
Garage rebuilt top end (don't know how well) and compression seems ok now as both them and I have retested independently and all cylinders now have compression and its within 15psi of each other.
Car seemed to run ok after the rebuild but still didn't have full power as explained above and further investigations were to happen early next month. The trouble is that last week things took a drastic turn for the worse and with the P0300 code and now engine really struggles to start and then is running really rough like it misfiring but no cylinder code is coming up just the P0300 which I'm told and have read could be a myriad of things.
Tests revealed one bad injector which I have now replaced as well as plugs and coils but still same. Don't know if it's an air issue or fuel or something else as no air/o2 codes are coming up. I am fairly sure I have eliminated coils, plugs and injectors along with compression and can see fuel getting to injectors so apart from air mix or possible weak fuel pressure issue I'm really stuck as to what the hell it could be.
If I somehow had air getting into exhaust system near the O2 sensor which I've yet to check, could that cause really rough idle and drive? could the ECM be mixing fuel to air incorrectly?
Is it possible to have good cylinder compression yet still have top end issues?
Yes it is possible.The test procedure that I used for the coils which are individual is the way that the Nissan tech manual states for testing coils. It states to place the spark plug in the coil and then to position it at an angle between 13-17mm away from ground and that if the spark jumps that gap then coil is good and strong. I do accept that there are different ways of testing but unless all four coils are bad then the ECM would normally report which cyclinder is bad which initially it did and it was no 2 due to no compression.
Garage rebuilt top end (don't know how well) and compression seems ok now as both them and I have retested independently and all cylinders now have compression and its within 15psi of each other.
Car seemed to run ok after the rebuild but still didn't have full power as explained above and further investigations were to happen early next month. The trouble is that last week things took a drastic turn for the worse and with the P0300 code and now engine really struggles to start and then is running really rough like it misfiring but no cylinder code is coming up just the P0300 which I'm told and have read could be a myriad of things.
Tests revealed one bad injector which I have now replaced as well as plugs and coils but still same. Don't know if it's an air issue or fuel or something else as no air/o2 codes are coming up. I am fairly sure I have eliminated coils, plugs and injectors along with compression and can see fuel getting to injectors so apart from air mix or possible weak fuel pressure issue I'm really stuck as to what the hell it could be.
If I somehow had air getting into exhaust system near the O2 sensor which I've yet to check, could that cause really rough idle and drive? could the ECM be mixing fuel to air incorrectly?
Is it possible to have good cylinder compression yet still have top end issues?
Coils/plugs are still possible too.
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