QX4 mis firing
QX4 mis firing
My 98 QX4 has started mis firing when it gets to operating temperture. When it is cold it runs fine, but a few miles down the road when the temp. starts to rise it starts jumping like it is misfiring. I have read several post but still have not had any resouloutin. I have taken it to the local auto parts store to check for any codes and there is none. I have replaced the plugs, plug wires, rotor button and the distributor cap. Still have the same problem. I also removed the MAF sensor and cleaned it with proper spray. Any help would greatly be apprecated.
Re: QX4 mis firing
Is the misfire noticeable when the car is stopped in and in drive, how about at idle in park, if so, does it shudder, lurch or have very noticeable symptoms when not pulling a load? Ignition system issues, while not always, are most noticeable under a load rather then at cruising or idle. Fuel related, too. again, not always, but troubleshoot most likely areas first, then work back. Vacuum leaks can make the vehicle shudder and run poorly under any conditions - load or rest and are often noticeable when engine is warm and can result from a number of causes--a switched solenoid for ex.EGR valve worn stem/seal can result in a vacuum leak, a transmission module diaphram ( any white smoke at exhaust?), the same. A leaking manifold or egr gasket is a possibility and often occurs only when engine temperatures rise due to the normal expansion of the parts they are sealing. Leaking brake poser booster-see that big vacuum hose..? What goes in can come out.Shortcuts can turn into Long trips.
When the misfire occurs and the car in park with brake on and wheels chocked, listen for the hissing sound of vacuum leaks. Visibly check for residue indicating gas going out vis a vis air going in, around injector seals and gaskets which could indicate a bad seal. Lean conditions--namely Intake leaks-- account for the majority of misfires. Use a pair of needle nose pliers to pinch off vacuum lines between the manifold and the device they go to and listen for a decrease in engine RPM and smoother idle. Using a bottle of propane with a vacuum line on the threaded end of the valve with torch bit disconnected (not lit, mind you- lol), carefully inject small squirts of gas around any intake sources--injector seals, manifold, egr valve etc. if no propane is available, SO CAREFULLY unless your idea of a fun afternoon is extinguishing your previously BBQ'd Nissan) use carb cleaner with the spray tube attached and spray with that. Do not spray any electrical connections or the aforementioned will become a reality! A water bottle spray can also find some leaks and is safe.
Let's see what you come up with.
Re: QX4 mis firing
UCANDO listed a lot of things. When cold OK, when warn No good...ignition, lean and maybe timing. Timing may not be advancing.
Re: QX4 mis firing
It does it when in park, but only when I raise the idle up, about 200-2500 rpms.You can watch the rpm needle jump when it happens.It doesnt lurch more of a stumble. I dont tow anything with it so I dont put a heavy load on it. I will check for vacuum leaks and spray some carb cleaner like recomended. I will seem if I can get a timing light from the auto parts loan a tool and chack the timning. What would make the timing not advance? Also is timing something I need to check periodically?
Re: QX4 mis firing
xer1, We need to establish some clear parameters and knowing how the vehicle responds under these two conditions will help with the troubleshooting.
1. Is the misfire noticeable when the car is stopped in and in drive, y/n
2. At idle in park? y/n
Your right in that towing would constitute a "load" on engine, but for purposes of isolating the symptoms, I''m merely referring to the vehicle being in gear, where the trans itself puts a "load" on the engine, placing a greater demand on all components in the combustion cycle i.e ignition, fuel,air, and compression. The faster it's driven, or steeper incline, the greater the load and the more critical proper functioning of the systems are and the pronounced any deficiencies will be.
Timing is not adjustable and is monitored by the computer. Sensors are responsible for maintaining proper degree.
Another possibility, but this would NOT be temperature specific and would occur whether cold or hot, is a slack timing belt. At higher rpm the added tension on the belt would cause the valve timing to move out of sync by a couple of degrees which would make for a motor that doesn't want to go anywhere.
It's all about isolating known conditions...and patience, lots of patience. Let me know.
1. Is the misfire noticeable when the car is stopped in and in drive, y/n
2. At idle in park? y/n
Your right in that towing would constitute a "load" on engine, but for purposes of isolating the symptoms, I''m merely referring to the vehicle being in gear, where the trans itself puts a "load" on the engine, placing a greater demand on all components in the combustion cycle i.e ignition, fuel,air, and compression. The faster it's driven, or steeper incline, the greater the load and the more critical proper functioning of the systems are and the pronounced any deficiencies will be.
Timing is not adjustable and is monitored by the computer. Sensors are responsible for maintaining proper degree.
Another possibility, but this would NOT be temperature specific and would occur whether cold or hot, is a slack timing belt. At higher rpm the added tension on the belt would cause the valve timing to move out of sync by a couple of degrees which would make for a motor that doesn't want to go anywhere.
It's all about isolating known conditions...and patience, lots of patience. Let me know.
Re: QX4 mis firing
ucado, thanks for being patience with me. It is not noticeable when it is idling in park or when it is in drive. It is noticeable when drivine down the road. the timing belt was replaced about 35000 miles ago.It has about 138000 miles on it now. Hope this help you to help me.
thanks
thanks
Re: QX4 mis firing
xer1,
Any luck with the vacuum leak testing? Try this method for leak testing if you find nothing with the car in park with engine in idle and at varying rpm i.e. 2000-3000 rpm.
The next test will require a helper you can communicate well with. We'll test for 2 things:
--Ignition misfire under load,
---Vacuum leaks.
First Ignition misfire.
With engine OFF, one at a time, pull each plug wire out of the distributor tower and then set the wire back in the SAME tower with out snapping it in so that all six wires can be lifted out of their respective towers one at a time and set back in with out using much force to do so. Next, with an assistant sitting in the vehicle with parking brake fully engaged and wheels chocked ,place the transmission in drive and, working from the sides so you don't get squished if your helper forgets for a second, he has your life in his hands
, try to obtain the rpms where the misfire occurs. If the misfire can be replicated pull the wires out one at a time USING INSULATED SPARK PLUG PLIERS, OR ANY WELL INSULATED TOOL THAT WILL GRASP THE WIRE AND GIVE YOU GOOD CONTROL OF IT, and look/listen for the cylinder that has NO effect on the engine performance and/or RPM. Theory: If a cylinder is cutting out, regardless of the cause (ignition, fuel, air leak, compression) when that cylinder is taken out of the firing order by removing the wire from the tower, there will be NO noticeable change in the performance of the engine (thus identifying the non-firing cylinder that is causing the misfire in the first place) and giving us a solid place to focus on. Even with a misfiring engine, there will always be cylinders which are firing properly or the vehicle would not run at all. Have your helper watch the tach while doing this test and note the rpm drop in each cylinder, to see how much of a contribution each cylinder is making to the performance of the engine and which one (if any) contributes less than the others or nothing at all.
When you've finished this, shut off and reattach plug wires securely then restart and using same method as prior, go around looking for air leaks and paying attention to any noticeable change in performance/rpm increase.
You'll want to be REAL thorough, and go over things 2-3 times and at the risk of not reiterating enough--BE CAREFUL NOT TO SPRAY ON ANY ELECTRICAL SOLENOID, SWITCH OR CONNECTOR (I always have a fire extinguisher close when doing this).
Also, I forgot to mention, as almost every engine function on your vehicle is controlled by the control monitor, I advise you to get your hands on a decent scan tool-one that gives out real time LIVE ENGINE DATA. Amazon has an Innova Equus 3130 scan tool for around a hundred and a half that is a third of the manufacture site. I saw it for a hundred on Ebay yesterday (new) w/ free shipping.
I think you'll hit on the problem if you take a methodical, consistent approach focusing on locating the cause, as opposed to jumping around trying to hit on what will "fix" it.
Happy hunting.
I'll be interested to learn what is causing the problem.
Have a great weekend.
Any luck with the vacuum leak testing? Try this method for leak testing if you find nothing with the car in park with engine in idle and at varying rpm i.e. 2000-3000 rpm.
The next test will require a helper you can communicate well with. We'll test for 2 things:
--Ignition misfire under load,
---Vacuum leaks.
First Ignition misfire.
With engine OFF, one at a time, pull each plug wire out of the distributor tower and then set the wire back in the SAME tower with out snapping it in so that all six wires can be lifted out of their respective towers one at a time and set back in with out using much force to do so. Next, with an assistant sitting in the vehicle with parking brake fully engaged and wheels chocked ,place the transmission in drive and, working from the sides so you don't get squished if your helper forgets for a second, he has your life in his hands
, try to obtain the rpms where the misfire occurs. If the misfire can be replicated pull the wires out one at a time USING INSULATED SPARK PLUG PLIERS, OR ANY WELL INSULATED TOOL THAT WILL GRASP THE WIRE AND GIVE YOU GOOD CONTROL OF IT, and look/listen for the cylinder that has NO effect on the engine performance and/or RPM. Theory: If a cylinder is cutting out, regardless of the cause (ignition, fuel, air leak, compression) when that cylinder is taken out of the firing order by removing the wire from the tower, there will be NO noticeable change in the performance of the engine (thus identifying the non-firing cylinder that is causing the misfire in the first place) and giving us a solid place to focus on. Even with a misfiring engine, there will always be cylinders which are firing properly or the vehicle would not run at all. Have your helper watch the tach while doing this test and note the rpm drop in each cylinder, to see how much of a contribution each cylinder is making to the performance of the engine and which one (if any) contributes less than the others or nothing at all. When you've finished this, shut off and reattach plug wires securely then restart and using same method as prior, go around looking for air leaks and paying attention to any noticeable change in performance/rpm increase.
You'll want to be REAL thorough, and go over things 2-3 times and at the risk of not reiterating enough--BE CAREFUL NOT TO SPRAY ON ANY ELECTRICAL SOLENOID, SWITCH OR CONNECTOR (I always have a fire extinguisher close when doing this).
Also, I forgot to mention, as almost every engine function on your vehicle is controlled by the control monitor, I advise you to get your hands on a decent scan tool-one that gives out real time LIVE ENGINE DATA. Amazon has an Innova Equus 3130 scan tool for around a hundred and a half that is a third of the manufacture site. I saw it for a hundred on Ebay yesterday (new) w/ free shipping.
I think you'll hit on the problem if you take a methodical, consistent approach focusing on locating the cause, as opposed to jumping around trying to hit on what will "fix" it.
Happy hunting.
I'll be interested to learn what is causing the problem.
Have a great weekend.
Re: QX4 mis firing
A mis-fire without codes identifying it may be a mis-fire non electrical. The spark to the firing cylinder may be there but the cylinder has a loss of compression by the valves, rings or timing.
Put a timing light on that vehicle, remove any vacuum line controlling the distributor if there and plug.
A good timing light is a good spark detector. Watch the read out, does it flicker, does the amount of light vary on a particular plug? Are your plugs clean and with a proper gap?
Check the distributor, inside of it there is a segmented plate that a LED and receiver work through, clean it.
With the firing issue coming at temperature test your coolant sensor and EGR valve. Look inside the throttle intake, if dirty clean with carb cleaner.
Your mileage indicates another timing belt change, test timing and see if the advance mechanism is working properly.
A spark tester at about $3 is a cheap tester and will indicate spark, but a good timing light with variable timing features verifies spark and at what degree. Giving a visual clue is easier to understand.
Are you running lean, when off enrichment when at temperature?
Does timing advance at higher RPM? How far at what rate?
Is recirculating exhaust gases interfering or plugged?
No codes, means look at things other than electrics.
Your problem must be diagnosed and things eliminated 1 at a time and recorded so you do not forgot what was done and what is still needed to do.
Be meticulous in finding the problem and good luck
Put a timing light on that vehicle, remove any vacuum line controlling the distributor if there and plug.
A good timing light is a good spark detector. Watch the read out, does it flicker, does the amount of light vary on a particular plug? Are your plugs clean and with a proper gap?
Check the distributor, inside of it there is a segmented plate that a LED and receiver work through, clean it.
With the firing issue coming at temperature test your coolant sensor and EGR valve. Look inside the throttle intake, if dirty clean with carb cleaner.
Your mileage indicates another timing belt change, test timing and see if the advance mechanism is working properly.
A spark tester at about $3 is a cheap tester and will indicate spark, but a good timing light with variable timing features verifies spark and at what degree. Giving a visual clue is easier to understand.
Are you running lean, when off enrichment when at temperature?
Does timing advance at higher RPM? How far at what rate?
Is recirculating exhaust gases interfering or plugged?
No codes, means look at things other than electrics.
Your problem must be diagnosed and things eliminated 1 at a time and recorded so you do not forgot what was done and what is still needed to do.
Be meticulous in finding the problem and good luck
Re: QX4 mis firing
Ok Im back . I bought a spark tester and found that I was getting spark. I tried the method for checking for vacuum leaks and found nothing. I unplug the wires as described on the distributor and found nothing that was described. I did not buy a scan tool yet, but may have too in the future. Oh the timing belt was replaced at 98000 miles. I am under the impression that this should be done at 100,000 mile interval, right? did not try the timing light yet. I spoke with a person at work that had a nissqn mini van and he said it done the same thing as I am seeing. He took his to the dealer and they replaced the distributor. I know the coil is in the distributor, is there anyway to check it, or should the checks I have done would have pointed me in that direction? Still not getting any codes. Thanks
Re: QX4 mis firing
If you open and examine the distributor blow compressed air at low pressure, a 98 is like a 97 QX4. The system is simple but a dirty dusty LED , split view and receiver all for the LED to help trigger the point of coil induction may cause what you experience.
Be cautious and use extreme care in blowing the system clear of dust, if it has not been done you should see a very small dust ball rise out of the distributor. Clean the plastic non conductive spark wire holder in and out and visualize the carbon brush inserts that signal each plug. The contact arrangement is to not touch but at high voltage the arrangement is proximity, the spark gap inside the distributor will cause park erosion or build up on the rotor, do not sand or file the rotor.
A dusting should be all that is needed, examine the center shaft for rotational wear, if none after cleaning make sure the cap has no scratches or wear marks and is clean, no finger prints allowed. Replace and rewire, the HT leads are numbered and you should know the firing order. When all assembled clean off with a clean dry lint free cloth.
Test fire and see if it runs better than before. Since your doing this replace the plugs and gap with a wire gauge at minimum spec, the range for a 97 QX4 is .039" to .043" so I do them no more than .040" and let them wear to the bigger spec gap over time.
Be cautious and use extreme care in blowing the system clear of dust, if it has not been done you should see a very small dust ball rise out of the distributor. Clean the plastic non conductive spark wire holder in and out and visualize the carbon brush inserts that signal each plug. The contact arrangement is to not touch but at high voltage the arrangement is proximity, the spark gap inside the distributor will cause park erosion or build up on the rotor, do not sand or file the rotor.
A dusting should be all that is needed, examine the center shaft for rotational wear, if none after cleaning make sure the cap has no scratches or wear marks and is clean, no finger prints allowed. Replace and rewire, the HT leads are numbered and you should know the firing order. When all assembled clean off with a clean dry lint free cloth.
Test fire and see if it runs better than before. Since your doing this replace the plugs and gap with a wire gauge at minimum spec, the range for a 97 QX4 is .039" to .043" so I do them no more than .040" and let them wear to the bigger spec gap over time.
Re: QX4 mis firing
My 98 QX4 was missing all the time too. Kept throwing codes P0300, P0302, and P0306. What I did to fix mine was I put 6 bottles of fuel system cleaner with only 2 - 3 gallons of fuel in the tank. Now there is no misfire anymore. I did this about 6 months ago.
Re: QX4 mis firing
I blew out the distributor and it had a brownish dust come out. Drove it the next couple of days and it still was mis firing. I broke down and bought a distributor and the problem went away. thanks for all the input on troubleshooting my problem. this is a great forum, wish I had more knowledge to help others.
thanks everyone
thanks everyone
Re: QX4 mis firing
Brownish substance in a distributor is rust, blowing it out cleans it until it settles again, blow it again and again until clean. Then with a fine paint brush wipe out the slots and the LED and receiver, Wipe out the Bakelite distributor cap with a soft clean cloth, lint-free, may need to wipe with contact cleaner and blow dry. Let completely dry, visualize that all is clean then button up and do every 2-3 years. Now clean your HT leads with a clean cloth and blow out the plug holes with the plugs in.