Car idles with abnormal popping sound
11-07-2008, 08:33 PM
#21
Registered User
iTrader: (8)
Join Date: Aug 2008
Location: bel air, MD
Posts: 633
Likes: 0
Received 0 Likes
on
0 Posts
i have this issue as well with my g35, took it to a couple of dealers until I took it to a nice deleware infiniti dealer. only at idle etc etc...our best guess is its something in the transmission drivetrain assembly that sends enough of a shock to be heard and felt everywhere, its less noticeable if i have the car in gear.
this guy tried everything, he checked for codes, he checked readings while the noise was there, he even busted out the stethoscope and listened in a few areas. everything except the noise was within spec.
we were both kind of still in awe of what it might be but his best guess was something in the trans, maybe the clutchor dual mass flywheel, he wasnt sure exactly.
this guy tried everything, he checked for codes, he checked readings while the noise was there, he even busted out the stethoscope and listened in a few areas. everything except the noise was within spec.
we were both kind of still in awe of what it might be but his best guess was something in the trans, maybe the clutchor dual mass flywheel, he wasnt sure exactly.
11-08-2008, 12:34 AM
#23
Registered User
Thread Starter
Join Date: May 2008
Location: United Kingdom
Posts: 145
Likes: 0
Received 0 Likes
on
0 Posts
Looks like this is a common problem that no one has found a fix yet. 
idrive_MD>> Interesting post, I didn't tot of trying the idling with first gear engaged. Will try when I get in car later.I have a friend suggesting clutch as well... but I still think it is something to do with ignition? Something like misfiring, detonation?
Anyway I am going to change my clutch in a couple of months, so I will find out.
idrive_MD>> Interesting post, I didn't tot of trying the idling with first gear engaged. Will try when I get in car later.I have a friend suggesting clutch as well... but I still think it is something to do with ignition? Something like misfiring, detonation?
Anyway I am going to change my clutch in a couple of months, so I will find out.
11-09-2008, 07:26 AM
#27
Registered User
Join Date: Jul 2008
Location: Texas
Posts: 81
Likes: 0
Received 0 Likes
on
0 Posts
Normally, and I say normally, a pop in the exhaust is due to a lean condition or an air leak in the exhaust.
An old hotrodder trick was to barely losen a header bolt enough to allow air to be pulled into the exhaust during idle. The additional air allowed the unburned fuel to ignite. It made it sound like the car was out of tune. It didn't pop all the time, just every so often. If you gave it a little gas now and then, the popping would increase, making it a little worse. Pull up to the red light and the guy next to you thought your car was mucked up. Light turns green, you hit the throttle and blow them away.
The lean condition on intake can cause a popping also, not so much with fuel injection, but if the A/F ratio is too lean, it may not have time to burn before the exhaust valve is opened.
If you've changed anything on the intake to increase air flow, it might be getting you on the hairy edge for idle. I'm just getting started on the 350Z so I haven't had time to fully review how the "brains" interact and what learn modes it has, but I would suspect in closed loop operation it would adjust the A/F ratio enough to avoid this pop.
But then again if you have an injector that is sticking or sluggish once in a while or maybe a tad dirty, there's your lean mixture. The ECU adjusts for a prime mixture, once in while this particular problem child drags a bit and causes a lean mixture and then a pop.
I used to have a rig for testing injectors, back in the day, we would test the flow rates and put them in as matched sets. The flow rates from the factory were never matched perfect. The rig was also good for seeing problem children, I could vary the pulse width and see how they acted.
My money is on a sluggish injector, at idle the pulse width is very short, the injector works fine with a longer pulse, but hangs a bit on a shorter pulse. The ECU makes the corrections after a pop, kicks up the A/F ratio, then as you sit idling, the ECU trims the A/F back, the injector hangs, pop and then the A/F is kicked up again and the cycle continues.
An old hotrodder trick was to barely losen a header bolt enough to allow air to be pulled into the exhaust during idle. The additional air allowed the unburned fuel to ignite. It made it sound like the car was out of tune. It didn't pop all the time, just every so often. If you gave it a little gas now and then, the popping would increase, making it a little worse. Pull up to the red light and the guy next to you thought your car was mucked up. Light turns green, you hit the throttle and blow them away.
The lean condition on intake can cause a popping also, not so much with fuel injection, but if the A/F ratio is too lean, it may not have time to burn before the exhaust valve is opened.
If you've changed anything on the intake to increase air flow, it might be getting you on the hairy edge for idle. I'm just getting started on the 350Z so I haven't had time to fully review how the "brains" interact and what learn modes it has, but I would suspect in closed loop operation it would adjust the A/F ratio enough to avoid this pop.
But then again if you have an injector that is sticking or sluggish once in a while or maybe a tad dirty, there's your lean mixture. The ECU adjusts for a prime mixture, once in while this particular problem child drags a bit and causes a lean mixture and then a pop.
I used to have a rig for testing injectors, back in the day, we would test the flow rates and put them in as matched sets. The flow rates from the factory were never matched perfect. The rig was also good for seeing problem children, I could vary the pulse width and see how they acted.
My money is on a sluggish injector, at idle the pulse width is very short, the injector works fine with a longer pulse, but hangs a bit on a shorter pulse. The ECU makes the corrections after a pop, kicks up the A/F ratio, then as you sit idling, the ECU trims the A/F back, the injector hangs, pop and then the A/F is kicked up again and the cycle continues.
11-09-2008, 03:48 PM
#28
Registered User
Join Date: Jan 2008
Location: Palmetto, Florida
Posts: 90
Likes: 0
Received 0 Likes
on
0 Posts
Mine does the same thing and I have a 04 Base. With the poping sound coming from the exhaust and the engine having a very slight miss every 10-15 secs ( more with the A/C off) with no codes coming up.Considering it runs 14's flat bone stock and my old 240 and friends of mine Xterra have a slight engine miss in them too, Ive come to conclude its just the way they were engineered, thus stopped being so paranoid on whats causing it. One of the quickest ways to break something is to fix it when it isn't broken, aKa, If it ain't broke, don't fix it.
11-10-2008, 04:06 AM
#29
Registered User
iTrader: (1)
Join Date: May 2008
Location: Toronto, Ontario (Woodbridge)
Posts: 1,174
Likes: 0
Received 1 Like
on
1 Post
Normally, and I say normally, a pop in the exhaust is due to a lean condition or an air leak in the exhaust.
An old hotrodder trick was to barely losen a header bolt enough to allow air to be pulled into the exhaust during idle. The additional air allowed the unburned fuel to ignite. It made it sound like the car was out of tune. It didn't pop all the time, just every so often. If you gave it a little gas now and then, the popping would increase, making it a little worse. Pull up to the red light and the guy next to you thought your car was mucked up. Light turns green, you hit the throttle and blow them away.
The lean condition on intake can cause a popping also, not so much with fuel injection, but if the A/F ratio is too lean, it may not have time to burn before the exhaust valve is opened.
If you've changed anything on the intake to increase air flow, it might be getting you on the hairy edge for idle. I'm just getting started on the 350Z so I haven't had time to fully review how the "brains" interact and what learn modes it has, but I would suspect in closed loop operation it would adjust the A/F ratio enough to avoid this pop.
But then again if you have an injector that is sticking or sluggish once in a while or maybe a tad dirty, there's your lean mixture. The ECU adjusts for a prime mixture, once in while this particular problem child drags a bit and causes a lean mixture and then a pop.
I used to have a rig for testing injectors, back in the day, we would test the flow rates and put them in as matched sets. The flow rates from the factory were never matched perfect. The rig was also good for seeing problem children, I could vary the pulse width and see how they acted.
My money is on a sluggish injector, at idle the pulse width is very short, the injector works fine with a longer pulse, but hangs a bit on a shorter pulse. The ECU makes the corrections after a pop, kicks up the A/F ratio, then as you sit idling, the ECU trims the A/F back, the injector hangs, pop and then the A/F is kicked up again and the cycle continues.
An old hotrodder trick was to barely losen a header bolt enough to allow air to be pulled into the exhaust during idle. The additional air allowed the unburned fuel to ignite. It made it sound like the car was out of tune. It didn't pop all the time, just every so often. If you gave it a little gas now and then, the popping would increase, making it a little worse. Pull up to the red light and the guy next to you thought your car was mucked up. Light turns green, you hit the throttle and blow them away.
The lean condition on intake can cause a popping also, not so much with fuel injection, but if the A/F ratio is too lean, it may not have time to burn before the exhaust valve is opened.
If you've changed anything on the intake to increase air flow, it might be getting you on the hairy edge for idle. I'm just getting started on the 350Z so I haven't had time to fully review how the "brains" interact and what learn modes it has, but I would suspect in closed loop operation it would adjust the A/F ratio enough to avoid this pop.
But then again if you have an injector that is sticking or sluggish once in a while or maybe a tad dirty, there's your lean mixture. The ECU adjusts for a prime mixture, once in while this particular problem child drags a bit and causes a lean mixture and then a pop.
I used to have a rig for testing injectors, back in the day, we would test the flow rates and put them in as matched sets. The flow rates from the factory were never matched perfect. The rig was also good for seeing problem children, I could vary the pulse width and see how they acted.
My money is on a sluggish injector, at idle the pulse width is very short, the injector works fine with a longer pulse, but hangs a bit on a shorter pulse. The ECU makes the corrections after a pop, kicks up the A/F ratio, then as you sit idling, the ECU trims the A/F back, the injector hangs, pop and then the A/F is kicked up again and the cycle continues.
In my experience tuning ECU systems when an exhaust system is popping it's due to low timing at idle. The timing is retarded so far that the combustion is still happening while the exhaust valve opens and you can hear it through the exhaust system. Kinda like rally cars when you hear them popping while going around corners known as Bang-Bang (http://www.rallycars.com/Cars/bangbang.html) it's all due to timing being pulled way back.
In our cars however we have no control over timing. SO a few things that would alter that is the Air Intake Temperature Sensor, and general readings from the Maf. More likely it's a coil that is not producing a strong spark anymore (which is why changing the plugs didn't fix the problem) and the fuel is igniting late or being ignited by the cat once it gets there producing the sound you are hearing. Many coils will operate normally under hard acceleration with no problems but fail at idle, why this happens I do not know.
When you pulled your plugs out did they all look exactly the same or were any different colors? A plug reading will give you some idea if a coil is not working properly. Otherwise I would swap coils with somebody to can lend you theirs (about 30 mins a car to swap) who is not experiencing that problem.
Regards,
11-10-2008, 04:45 AM
#30
Registered User
Thread Starter
Join Date: May 2008
Location: United Kingdom
Posts: 145
Likes: 0
Received 0 Likes
on
0 Posts
I didn't look at the spark plug myself to check for any abnormalities, but I assume there isn't any as I trust the workshop pretty much.
Good news is, my engine check light came up this morning, will bring my car to the workshop to check the OBD code. Of coz the check light might not be related to the popping, but I hope it is, so I can fix it and rev the car without hesitation. I am sure it will help many, as no one really know where or what is causing it.
Good news is, my engine check light came up this morning, will bring my car to the workshop to check the OBD code. Of coz the check light might not be related to the popping, but I hope it is, so I can fix it and rev the car without hesitation. I am sure it will help many, as no one really know where or what is causing it.
Good ideas...
In my experience tuning ECU systems when an exhaust system is popping it's due to low timing at idle. The timing is retarded so far that the combustion is still happening while the exhaust valve opens and you can hear it through the exhaust system. Kinda like rally cars when you hear them popping while going around corners known as Bang-Bang (http://www.rallycars.com/Cars/bangbang.html) it's all due to timing being pulled way back.
In our cars however we have no control over timing. SO a few things that would alter that is the Air Intake Temperature Sensor, and general readings from the Maf. More likely it's a coil that is not producing a strong spark anymore (which is why changing the plugs didn't fix the problem) and the fuel is igniting late or being ignited by the cat once it gets there producing the sound you are hearing. Many coils will operate normally under hard acceleration with no problems but fail at idle, why this happens I do not know.
When you pulled your plugs out did they all look exactly the same or were any different colors? A plug reading will give you some idea if a coil is not working properly. Otherwise I would swap coils with somebody to can lend you theirs (about 30 mins a car to swap) who is not experiencing that problem.
Regards,
In my experience tuning ECU systems when an exhaust system is popping it's due to low timing at idle. The timing is retarded so far that the combustion is still happening while the exhaust valve opens and you can hear it through the exhaust system. Kinda like rally cars when you hear them popping while going around corners known as Bang-Bang (http://www.rallycars.com/Cars/bangbang.html) it's all due to timing being pulled way back.
In our cars however we have no control over timing. SO a few things that would alter that is the Air Intake Temperature Sensor, and general readings from the Maf. More likely it's a coil that is not producing a strong spark anymore (which is why changing the plugs didn't fix the problem) and the fuel is igniting late or being ignited by the cat once it gets there producing the sound you are hearing. Many coils will operate normally under hard acceleration with no problems but fail at idle, why this happens I do not know.
When you pulled your plugs out did they all look exactly the same or were any different colors? A plug reading will give you some idea if a coil is not working properly. Otherwise I would swap coils with somebody to can lend you theirs (about 30 mins a car to swap) who is not experiencing that problem.
Regards,
11-10-2008, 05:05 AM
#32
Registered User
Thread Starter
Join Date: May 2008
Location: United Kingdom
Posts: 145
Likes: 0
Received 0 Likes
on
0 Posts
After the check light came up, car becomes sluggish and during suddenly rev goes up as if I stepped on the accelerator.
After I stop and restarted the engine, the sympton is gone, but the check light is still there....
seems like some intake issue. Maybe its the sensor, will check OBD code tomorrow.
After I stop and restarted the engine, the sympton is gone, but the check light is still there....
seems like some intake issue. Maybe its the sensor, will check OBD code tomorrow.
11-10-2008, 05:24 AM
#33
Registered User
iTrader: (2)
Join Date: Jul 2008
Location: Northwest Arkansas
Posts: 294
Likes: 0
Received 0 Likes
on
0 Posts
I'm curious to see what the code says.
Saturday night, my car idled in the parking lot (while a few people were standing around talking) for about 45min, and it never did it.
The only thing that I did was re-torque all of the hose clamps that are on the intake, and also the bolts that hold the upper plenum on.
I found a couple to be a little loose.
-Tim
Saturday night, my car idled in the parking lot (while a few people were standing around talking) for about 45min, and it never did it.
The only thing that I did was re-torque all of the hose clamps that are on the intake, and also the bolts that hold the upper plenum on.
I found a couple to be a little loose.
-Tim
11-10-2008, 07:48 AM
#34
Registered User
Thread Starter
Join Date: May 2008
Location: United Kingdom
Posts: 145
Likes: 0
Received 0 Likes
on
0 Posts
I'm curious to see what the code says.
Saturday night, my car idled in the parking lot (while a few people were standing around talking) for about 45min, and it never did it.
The only thing that I did was re-torque all of the hose clamps that are on the intake, and also the bolts that hold the upper plenum on.
I found a couple to be a little loose.
-Tim
Saturday night, my car idled in the parking lot (while a few people were standing around talking) for about 45min, and it never did it.
The only thing that I did was re-torque all of the hose clamps that are on the intake, and also the bolts that hold the upper plenum on.
I found a couple to be a little loose.
-Tim
Keep us updated if the problem resurface.
11-10-2008, 03:46 PM
#36
Registered User
Join Date: Jul 2008
Location: Texas
Posts: 81
Likes: 0
Received 0 Likes
on
0 Posts
Good ideas...
In my experience tuning ECU systems when an exhaust system is popping it's due to low timing at idle. The timing is retarded so far that the combustion is still happening while the exhaust valve opens and you can hear it through the exhaust system. Kinda like rally cars when you hear them popping while going around corners known as Bang-Bang (http://www.rallycars.com/Cars/bangbang.html) it's all due to timing being pulled way back.
In our cars however we have no control over timing. SO a few things that would alter that is the Air Intake Temperature Sensor, and general readings from the Maf. More likely it's a coil that is not producing a strong spark anymore (which is why changing the plugs didn't fix the problem) and the fuel is igniting late or being ignited by the cat once it gets there producing the sound you are hearing. Many coils will operate normally under hard acceleration with no problems but fail at idle, why this happens I do not know.
When you pulled your plugs out did they all look exactly the same or were any different colors? A plug reading will give you some idea if a coil is not working properly. Otherwise I would swap coils with somebody to can lend you theirs (about 30 mins a car to swap) who is not experiencing that problem.
Regards,
In my experience tuning ECU systems when an exhaust system is popping it's due to low timing at idle. The timing is retarded so far that the combustion is still happening while the exhaust valve opens and you can hear it through the exhaust system. Kinda like rally cars when you hear them popping while going around corners known as Bang-Bang (http://www.rallycars.com/Cars/bangbang.html) it's all due to timing being pulled way back.
In our cars however we have no control over timing. SO a few things that would alter that is the Air Intake Temperature Sensor, and general readings from the Maf. More likely it's a coil that is not producing a strong spark anymore (which is why changing the plugs didn't fix the problem) and the fuel is igniting late or being ignited by the cat once it gets there producing the sound you are hearing. Many coils will operate normally under hard acceleration with no problems but fail at idle, why this happens I do not know.
When you pulled your plugs out did they all look exactly the same or were any different colors? A plug reading will give you some idea if a coil is not working properly. Otherwise I would swap coils with somebody to can lend you theirs (about 30 mins a car to swap) who is not experiencing that problem.
Regards,
""Many coils will operate normally under hard acceleration with no problems but fail at idle, why this happens I do not know.""
Good food for thought, it'll keep me busy for a while, but what comes to mind is heat and air flow. Like I said before, I'm just getting started on this Z so it'll take me a while to figure these things out.
11-10-2008, 06:05 PM
#37
Former Sponsor
iTrader: (564)
Join Date: Feb 2003
Location: Long Island, New York
Posts: 19,266
Likes: 0
Received 5 Likes
on
5 Posts
I didn't look at the spark plug myself to check for any abnormalities, but I assume there isn't any as I trust the workshop pretty much.
Good news is, my engine check light came up this morning, will bring my car to the workshop to check the OBD code. Of coz the check light might not be related to the popping, but I hope it is, so I can fix it and rev the car without hesitation. I am sure it will help many, as no one really know where or what is causing it.
Good news is, my engine check light came up this morning, will bring my car to the workshop to check the OBD code. Of coz the check light might not be related to the popping, but I hope it is, so I can fix it and rev the car without hesitation. I am sure it will help many, as no one really know where or what is causing it.
FWIW I had this EXACT issue on my own car about a month ago that happened only after I had removed the plenums to fix a leaking valvecover gasket. Turned out to be a loose manifold bolt at the collector. I also took the time to test my coils and found 2 were a bit of of spec, so I replaced all of them as safe measure. Once those were done, all was right with the world again.
Remember, the car is modern but the combustion engine isn't. For all it's fancy sensors, and cam timing changes, and CAN network devices, it still runs on very, very simplistic, basic things. Start with those and a large majority of things can be solved
04-14-2009, 01:10 AM
#39
Registered User
Thread Starter
Join Date: May 2008
Location: United Kingdom
Posts: 145
Likes: 0
Received 0 Likes
on
0 Posts
The checklight gave me the usual code that I get once in a while, nothing special.i get them whenever I drive in very heavy rain.
let's hope it gives you a specific cylinder misfire and not the random misfire code
FWIW I had this EXACT issue on my own car about a month ago that happened only after I had removed the plenums to fix a leaking valvecover gasket. Turned out to be a loose manifold bolt at the collector. I also took the time to test my coils and found 2 were a bit of of spec, so I replaced all of them as safe measure. Once those were done, all was right with the world again.
Remember, the car is modern but the combustion engine isn't. For all it's fancy sensors, and cam timing changes, and CAN network devices, it still runs on very, very simplistic, basic things. Start with those and a large majority of things can be solved
FWIW I had this EXACT issue on my own car about a month ago that happened only after I had removed the plenums to fix a leaking valvecover gasket. Turned out to be a loose manifold bolt at the collector. I also took the time to test my coils and found 2 were a bit of of spec, so I replaced all of them as safe measure. Once those were done, all was right with the world again.
Remember, the car is modern but the combustion engine isn't. For all it's fancy sensors, and cam timing changes, and CAN network devices, it still runs on very, very simplistic, basic things. Start with those and a large majority of things can be solved
04-14-2009, 07:23 AM
#40
Super Moderator
MY350Z.COM
MY350Z.COM
iTrader: (8)
My car pops at idle too, every 10 to 15 seconds. Actually every Z i've ever been in does this once the intake and or exhaust have been swapped.
I also get a CEL in the rain (sometimes ) i need to check the code next time. Now that its heating up, i'll start getting EVAP codes all summer.
I also get a CEL in the rain (sometimes ) i need to check the code next time. Now that its heating up, i'll start getting EVAP codes all summer.