Misfire, fuel injector problem?
03-29-2007, 07:52 PM
#1
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Thread Starter
Join Date: Aug 2005
Posts: 133
Misfire, fuel injector problem?
Two weeks ago, my Max.(230K), started to shake once the engine starts up. Mechanic told me the one of the injector was bad, so I had all the inner bank injectors changed (all 3) to save future trouble. A week later, the car started to shake again and this time #4 injector (outer bank) went bad. I replace that one and now, the problem came back again.
I still have two more spare injectors ready. My question is how is it possible that every injectors are going bad one after another?
Could be some other problems?
I still have two more spare injectors ready. My question is how is it possible that every injectors are going bad one after another?
Could be some other problems?
03-29-2007, 08:24 PM
#2
Guest
Posts: n/a
it depends on why they were causing the misfire. if you got some bad/contaminated gas that caused the injectors to stick open, the yes it could affect all of them. but the most common cause of misfire is faulty ignition coils.
question -- how did your mechanic diagnose the bad injector(s)? did you have a misfire code for cylinder 4? did he listen to the injector with a s-scope and/or unplug the injector while the car was misfiring?
with 230k miles on your engine, and assuming you have never replaced/cleaned the injectors, I would not be surprised if they were all clogged/sticky. go ahead and install the other 2 that you have already purchased (you are doing the front bank yourself, I assume?).
out of curiosity, how much did he charge you to do the back bank? those require removal of the intake, and it was wise to do all 3.
question -- how did your mechanic diagnose the bad injector(s)? did you have a misfire code for cylinder 4? did he listen to the injector with a s-scope and/or unplug the injector while the car was misfiring?
with 230k miles on your engine, and assuming you have never replaced/cleaned the injectors, I would not be surprised if they were all clogged/sticky. go ahead and install the other 2 that you have already purchased (you are doing the front bank yourself, I assume?).
out of curiosity, how much did he charge you to do the back bank? those require removal of the intake, and it was wise to do all 3.
03-29-2007, 10:19 PM
#3
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Thread Starter
Join Date: Aug 2005
Posts: 133
Well, I had my friend take it to the mechanic cuz I wasn't around. One of the inner back was misfiring according to the code but the mechanic suggested to chang all 3 just in case other 2 inner bank injector acts up. The mechanic did the inner bank, which takes time to tear the whole engine, cost $645.
So right now, my inner banks are all new and including the left injector when viewing the hood is opened (sorry, dont know the # to the injectors).
My question is if all of my injectors are going/clogged are due to the high mileage. Why are they going one by one after each one is replaced?
So right now, my inner banks are all new and including the left injector when viewing the hood is opened (sorry, dont know the # to the injectors).
My question is if all of my injectors are going/clogged are due to the high mileage. Why are they going one by one after each one is replaced?
03-30-2007, 02:20 AM
#4
a misfire doesnt mean injector. a misfire could be a simple plug problem. could be a coil problem (esp a 99). could be deposit formation. you are getting screwed by your mechanic. find a new one that finds the problem before charging you a ton of $$ for the wrong solution.
03-30-2007, 04:19 AM
#5
I agree with 2da Mizzax.
My car was misfiring, throwing a misfire code for the rear bank.
I took it to Nissan where they told me it was a bad injector. Wanted to charge me $300 to change 1 rear bank injector. I had some spare coilpacks so I figured I would try them first just incase. Bingo. Problem solved. Been running about 20,000 miles on the same injectors since.
My car was misfiring, throwing a misfire code for the rear bank.
I took it to Nissan where they told me it was a bad injector. Wanted to charge me $300 to change 1 rear bank injector. I had some spare coilpacks so I figured I would try them first just incase. Bingo. Problem solved. Been running about 20,000 miles on the same injectors since.
03-30-2007, 05:09 AM
#7
depends on new or used. yes it is easy to change, but dont go buying coils until you know for sure that is the problem. is your CEL light on? what is the exact code? when was your last tuneup?
If you dont know the codes, go to autozone and get them for free.
If you dont know the codes, go to autozone and get them for free.
03-30-2007, 05:49 AM
#8
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Join Date: Aug 2005
Posts: 133
My CEL has been on for almost two years. Last time i checked when the light came on for the first time was for the O2 sensors.
This this the thing. The CEL is there from 2 years ago. I nevered got the O2 replaced. Whenever I drive after new injectors are placed, the CEL wil start to blink.
Are coilpacks the same as ignition coils? and how much are they?
This this the thing. The CEL is there from 2 years ago. I nevered got the O2 replaced. Whenever I drive after new injectors are placed, the CEL wil start to blink.
Are coilpacks the same as ignition coils? and how much are they?
03-30-2007, 06:16 AM
#9
coil packs are the same thing as ignition coils. $90 from a local dealer. Go get your codes pulled from autozone. change your O2 sensor. the light is there for a reason. when it blinks that is a BAD thing (unless you are in the process of pulling the codes yourself). driving with a bad O2 sensor will kill your plugs. will kill your mileage. will kill your Cat. It will cause shaking (if bad enough). you are prob full of deposits and the injectors and coils are porbably fine (alothough the injectors are prob covered in deposits). putting in a new coila nd ingoring that pretty orange light will do...................absolutely nothing. It takes 10 minutes to do it yourself and 3 minutes to get it done at autozone for free. get the codes.
If you can't do it yourself, have someone who knows about cars do it for you. it = pulling the codes and repairs.
If you can't do it yourself, have someone who knows about cars do it for you. it = pulling the codes and repairs.
03-30-2007, 06:52 AM
#14
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Posts: n/a
2 years on bad O2s? ouch. mizzax is right, you probably are coated with deposits everywhere combustion/exhaust touches, and that is causing this in one way or another. did your mechanic say anything about the O2? did he replace the spark plugs?
a blinking CEL means a bad misfire. bad enough to damage the O2s and the cat.
you probably did need new injectors, but you likely have several other problems as well. carbon fouled spark plugs would not surprise me. and a gunked up EGR system, sticky piston rings, gunked up PCV system (from the blowby), etc etc.
1) as mizzax said, go get your codes read at autozone or any parts store that has a loaner code reader. write down all the codes you get.
2) while you are doing that, get some NGK BKR5E11 plugs and put them in.
3) take pics of your old plugs (keep them in order according to their cylinder) and post them for us to see. this tells us a lot.
4) take a long screwdriver and, and with your ear to the handle, probe the injector cases and listen for the click-click-click sound. if they are not clicking they are stuck. if they are clicking, leave them alone for now. 2 and 6 (front bank left & right) are the only old ones left.
a blinking CEL means a bad misfire. bad enough to damage the O2s and the cat.
you probably did need new injectors, but you likely have several other problems as well. carbon fouled spark plugs would not surprise me. and a gunked up EGR system, sticky piston rings, gunked up PCV system (from the blowby), etc etc.
1) as mizzax said, go get your codes read at autozone or any parts store that has a loaner code reader. write down all the codes you get.
2) while you are doing that, get some NGK BKR5E11 plugs and put them in.
3) take pics of your old plugs (keep them in order according to their cylinder) and post them for us to see. this tells us a lot.
4) take a long screwdriver and, and with your ear to the handle, probe the injector cases and listen for the click-click-click sound. if they are not clicking they are stuck. if they are clicking, leave them alone for now. 2 and 6 (front bank left & right) are the only old ones left.
03-30-2007, 06:56 AM
#15
Supporting Maxima.org Member
Join Date: Nov 2005
Location: New York
Posts: 304
Pilot8680, do you know what function your O2 sensor performs? You have two upstream O2 sensors that are responsible for communicating your necessary fuel adjustment back to your car's computer. This is the basis of electronic fuel injection. There is no excuse for ignoring a CEL that has been on for two years, unless of course you have done dramatically drastic modifications such as auto to manual trans/non-vq30de engine swap then it could be expected (I do not think this is your case). You can either extract the blink codes yourself with a standardhead screwdriver by running the ECU diagnostic mode and then decoding them online at (vbxmaxima.8m.com/ecudecoder.html) or go to autozone as someone has already mentioned. REPLACE YOUR OXYGEN SENSORS and have your combustion chamber flushed of deposits, but your coilpacks may also need attention. Get your codes checked that should be your first step in solving this problem. Actually, maybe you should find a new mechanic first. Good luck!
03-30-2007, 06:57 AM
#16
Pilot8680 - I'd like to offer you some constructive feedback. It seems that you're trying to figure out what was causing your car to misfire, yet your CEL has been on for years. Do yourself a favour and:
1) Order a replacement O2 sensor. You're burning up a lot of gas because the sensor is bad. The amount of extra gas you're burning, assuming that it's been for 2 years now, is probably triple or quadruple the cost of a replacement o2 sensor because your ECU is not able to tune itself properly.
2) READ THE FAQ's and do a search. Google can search this site just as easy. If you had actually searched the 4th gen forum, you would of figured out that the COIL packs on our maxima's cause rough idle. So does our intake manifold gaskets. If your PVC valve becomes gummed up, it'll cause your rubber gasket to be sucked in. That's happened to me.
3) You can a) clear your own CEL, and b) read the codes off the ECU with a simple small screwdriver (99) or a small flathead (95-98). How? Read the FAQ's.
4) Take this as a lesson learned. You have a great car, but you could be treating it better by getting that CEL checked when it first came on and then replacing that O2 sensor. I have a feeling you may not be taking care of your baby as good as you could be.
Finally, don't come into this forum expecting us to help you when you can't even help yourself. We all love helping out guys with really tough problems, but as long as they do their own due diligence. Read the FAQ's, get educated, then ask us sensible questions. There are thousands of Maxima owners who are very passionate about their cars. You have to earn that respect here by showing us you can learn, and that in turn, makes us want to help you. We could then learn what your car has done so in the future we can help others in a similar situation.
But for now, check the FAQ's, get educated about symptoms in doing a search, and come back and we'll have proper answers for your problems.
1) Order a replacement O2 sensor. You're burning up a lot of gas because the sensor is bad. The amount of extra gas you're burning, assuming that it's been for 2 years now, is probably triple or quadruple the cost of a replacement o2 sensor because your ECU is not able to tune itself properly.
2) READ THE FAQ's and do a search. Google can search this site just as easy. If you had actually searched the 4th gen forum, you would of figured out that the COIL packs on our maxima's cause rough idle. So does our intake manifold gaskets. If your PVC valve becomes gummed up, it'll cause your rubber gasket to be sucked in. That's happened to me.
3) You can a) clear your own CEL, and b) read the codes off the ECU with a simple small screwdriver (99) or a small flathead (95-98). How? Read the FAQ's.
4) Take this as a lesson learned. You have a great car, but you could be treating it better by getting that CEL checked when it first came on and then replacing that O2 sensor. I have a feeling you may not be taking care of your baby as good as you could be.
Finally, don't come into this forum expecting us to help you when you can't even help yourself. We all love helping out guys with really tough problems, but as long as they do their own due diligence. Read the FAQ's, get educated, then ask us sensible questions. There are thousands of Maxima owners who are very passionate about their cars. You have to earn that respect here by showing us you can learn, and that in turn, makes us want to help you. We could then learn what your car has done so in the future we can help others in a similar situation.
But for now, check the FAQ's, get educated about symptoms in doing a search, and come back and we'll have proper answers for your problems.
03-30-2007, 07:05 AM
#17
Originally Posted by MaximA VlaD
Who can explain why the CEL blinks after replacing the injectors? And what does that mean?
I did not know it could blink except when pulling codes...
I did not know it could blink except when pulling codes...
04-03-2007, 05:41 PM
#18
Member
Join Date: Jul 2005
Posts: 52
engine stalls after injector replacement - 94 maxima GXE
I am having some problems after replacing the injectors myself. The CEL light isnt on now, but the car just stalls a few seconds after i start the car. I can step on the pedal and the engine runs ok. its still a bit shaky at about 2k-3k rpm. at 1k rpm its very shaky and is about to stall. at about 500rpm i can step on the gas to maintain rpm (yea its pretty bad to even run it at 500rpm) and a little more i can rev it back up into the 2k-3k rpm. its very difficult to keep the engine between 1k-2k since the TPS is misaligned.
I changed the injector b/c the CEL came on before and checked all injectors and found one that was bad (#2). replaced it with OEM injector from dealer and connected all hoses back and replaced a vacuum hose i broke. i double checked the color sticker (yellow) for my 94 maxima SOHC GXE.
When i disassemble the manifold i did change the two gaskets (upper and lower). however i didnt have a torque wrench so i tightened them up by hand and tried to be even (did them in reverse order according to the manual since the instructions were for dissassembly). I tried not to exert too much force on these screws. I only have one screw left over from the dissassembly and its a 10 or 12mm hex screw, no phillips head top.
The potential problems i can spot:
b/c i broke the injector clip and i couldnt find a way to get the injector fully into the fuel tube, the engine manifold was exposed to humidity for a day since it was raining. The hood is closed so it didnt get wet, but its a concern.
also, since i couldnt manage to get the injector all the way into the fuel tube, the fuel line was probably exposed to the air and/or the humidity.
the TPS is probably misaligned and when i attempted to recalibrate it, i had to pull the trottle to almost full to get the TPS to register. Havent tried to check the resistance yet but will when i get a chance to do a more comprehensive check on it.
The gasket between the throttle body and intake manifold cracked in half (top and bottom) and had to play around with it to get all 4 screws back in there. could this be the problem? i had ordered the gaskets and will be in tomorrow. not sure if i have time before class to put them in.
I tried to let the engine run (with me applying pressure to the pedal so it wont stall, kept it at around 2k-3k rpm) for at least a minute to try to eliminate the air bubbles and/or moisture in the fuel lines. After this time, the engine became a bit more unstable even at 2k rpm than when i first started the engine.
I tried searching around for solutions on google and forums.maxima.org through google and didnt really find problems people had after changing out the injectors. This is my first post and hopefully its not too far off topic.
Any suggestions would be great. A list of potential problems and trouble parts to look at would be great as well.
I changed the injector b/c the CEL came on before and checked all injectors and found one that was bad (#2). replaced it with OEM injector from dealer and connected all hoses back and replaced a vacuum hose i broke. i double checked the color sticker (yellow) for my 94 maxima SOHC GXE.
When i disassemble the manifold i did change the two gaskets (upper and lower). however i didnt have a torque wrench so i tightened them up by hand and tried to be even (did them in reverse order according to the manual since the instructions were for dissassembly). I tried not to exert too much force on these screws. I only have one screw left over from the dissassembly and its a 10 or 12mm hex screw, no phillips head top.
The potential problems i can spot:
b/c i broke the injector clip and i couldnt find a way to get the injector fully into the fuel tube, the engine manifold was exposed to humidity for a day since it was raining. The hood is closed so it didnt get wet, but its a concern.
also, since i couldnt manage to get the injector all the way into the fuel tube, the fuel line was probably exposed to the air and/or the humidity.
the TPS is probably misaligned and when i attempted to recalibrate it, i had to pull the trottle to almost full to get the TPS to register. Havent tried to check the resistance yet but will when i get a chance to do a more comprehensive check on it.
The gasket between the throttle body and intake manifold cracked in half (top and bottom) and had to play around with it to get all 4 screws back in there. could this be the problem? i had ordered the gaskets and will be in tomorrow. not sure if i have time before class to put them in.
I tried to let the engine run (with me applying pressure to the pedal so it wont stall, kept it at around 2k-3k rpm) for at least a minute to try to eliminate the air bubbles and/or moisture in the fuel lines. After this time, the engine became a bit more unstable even at 2k rpm than when i first started the engine.
I tried searching around for solutions on google and forums.maxima.org through google and didnt really find problems people had after changing out the injectors. This is my first post and hopefully its not too far off topic.
Any suggestions would be great. A list of potential problems and trouble parts to look at would be great as well.
04-03-2007, 05:50 PM
#19
^^ Just a heads up....what you just did is threadjacking and you will get flamed by many members on here for doing it. In the future...get your 15 posts and make your own thread.
To me it sounds like its more than just your injectors/fuel lines. I am no mechanic but to me it sounds like its time to bring your car into the dealership and get their opinion. After that go to a trusty garage and see what they think. Then tackle the problem by doing it yourself or bringing it to a mechanic.
To me it sounds like its more than just your injectors/fuel lines. I am no mechanic but to me it sounds like its time to bring your car into the dealership and get their opinion. After that go to a trusty garage and see what they think. Then tackle the problem by doing it yourself or bringing it to a mechanic.
04-08-2007, 07:21 PM
#21
Donating Maxima.org Member
Join Date: Apr 2007
Posts: 5
did you ever get it figured out? the reason i ask is that my brother is having the same problems with his car recently
his O2 CEL was on for about 2 -3 years, we changed the knock sensor and both O2's. the EGR valve was almost clogged closed with black carbon build up. we cleared as much out of the Plenum as we could. put it all back together. eventually we will clean out or get a new egr valve
then it started hesitating and "misfiring" as diagnosed by a mechanic. My brother had the rear 3 injectors changed by a mechanic (aprox $800 parts and labor, should have done it when we did the knock sensor, but didn't have that problem at the time)
still same problem, mechanic said it was one of the front injectors. my bro changed out the one all the way to the right, had a hell of a time getting the old one out. then the car attempted to turn over then sounded like it froze up.
he thinks that some of the plastic on the bottom of the injector got into either the head or combustion chamber. Would that be enough to cause total engine failure? He is going to buy 2 more new injectors for the car, and call the mechanic this week about the problem. we'll check the pick n pull for cars like his Saturday.
the 15 reply rule sucks for your forum, (the forum doesn't suck) and it's the first time I have run into it, but you gotta keep the spammers out.... -1 and 14 more to go... flame me if you need to I am just trying to help my brother get his car going again. I will defiantly be checking out the forum more for tips on getting his car running better.
Thanks in advance!
his O2 CEL was on for about 2 -3 years, we changed the knock sensor and both O2's. the EGR valve was almost clogged closed with black carbon build up. we cleared as much out of the Plenum as we could. put it all back together. eventually we will clean out or get a new egr valve
then it started hesitating and "misfiring" as diagnosed by a mechanic. My brother had the rear 3 injectors changed by a mechanic (aprox $800 parts and labor, should have done it when we did the knock sensor, but didn't have that problem at the time)
still same problem, mechanic said it was one of the front injectors. my bro changed out the one all the way to the right, had a hell of a time getting the old one out. then the car attempted to turn over then sounded like it froze up.
he thinks that some of the plastic on the bottom of the injector got into either the head or combustion chamber. Would that be enough to cause total engine failure? He is going to buy 2 more new injectors for the car, and call the mechanic this week about the problem. we'll check the pick n pull for cars like his Saturday.
the 15 reply rule sucks for your forum, (the forum doesn't suck) and it's the first time I have run into it, but you gotta keep the spammers out.... -1 and 14 more to go... flame me if you need to I am just trying to help my brother get his car going again. I will defiantly be checking out the forum more for tips on getting his car running better.Thanks in advance!
04-08-2007, 07:51 PM
#22
donate and you dont have to wait for 15 posts. as for the maxima, why are you buying 2 more injectors? STOP THROWING PARTS AT CARS. And no the plastic will not cause enging failure unless it is HUGE and has melted or something.
04-08-2007, 08:02 PM
#23
Donating Maxima.org Member
Join Date: Apr 2007
Posts: 5
Originally Posted by 2da mizzax
donate and you dont have to wait for 15 posts. as for the maxima, why are you buying 2 more injectors? STOP THROWING PARTS AT CARS.
I don't have much time to check the site out now(working out of town sucks), but I might be able to throw in a couple bucks if I feel it's worth it (minumum donation or whatever). I can understand why the reason to ask to donate, I belong to two car clubs and the scca. I just can't join everything that asks me for money.
I am also wanting to get the egr valve body cleaned out. my bro isn't very mechanicly inclined, so I try to help out when i can, this has got me stumped. we'll be looking into it more so next weekend.
thanks
now
04-08-2007, 08:42 PM
#24
Member
Join Date: Jul 2005
Posts: 52
i think you and ur bro might personally check all the bolt connections (that you have to loosen to get stuff off to get to the injectors) and see if its tightened enough (or taut if u dont have a torque wrench). it might be a bit excessive, but check the bolts holding the lower intake manifold down. While your there, u might want to take it off and check the electrical connections (these are instructions for a 94 GXE; its probably similar for 4th gen). My problem was that the bolts for the IAC/AAC was pretty loose. i just winged some of the bolt connections and wanted to see if it cranked; then i forgot.
also, please clarify what the engine does. does it stall and at what rpm? does it even crank and start? can you keep the engine going if u step on the pedal? if its exactly what happened to me (instead of the person asking the original question), then make sure all the bolts are tightened.
if you think it was the injector problem in the first place, you should've checked the resistance of each of them (there are instructions on how to check them in the technical manual). they should be in the 10 ohm range. thats what i did and thats how i narrowed it down to only one injector. the others are all a bit lower resistance so i think in a few years all of them will fail all at once.
u might want to check the ECU and see what code it spits out; it might give u a clue about whats wrong. in my case there was no error, just the inability for the air motor to control the air going into the engine.
Since u brought it to the shop and its still broken, chances are hes just milking you for more money (and did he say why it was the back 3 injectors and not the front 3 or why 3 instead of just one; i believe the front 3 are easier to take off so he could charge u more for the back 3 but thats my guess). i suggest u try to figure it out on ur own. my family has never trusted those shops and other relatives got scr**ed by shop ppl. eventually they took it to my dad and got it fixed.
if hes not mechanically inclined and hes a guy, he will be once hes done figuring it out. just keep checking and be suspecious of everything. i just hope the shop guy didnt sabatoge something so u'll come back.
im usually in the 3rd gen thread (thought this thread was in 3rd gen; came here through google) and i asked the same question there (check for "engine stall after injector replacement"). they gave a few good tips to check on.
also, please clarify what the engine does. does it stall and at what rpm? does it even crank and start? can you keep the engine going if u step on the pedal? if its exactly what happened to me (instead of the person asking the original question), then make sure all the bolts are tightened.
if you think it was the injector problem in the first place, you should've checked the resistance of each of them (there are instructions on how to check them in the technical manual). they should be in the 10 ohm range. thats what i did and thats how i narrowed it down to only one injector. the others are all a bit lower resistance so i think in a few years all of them will fail all at once.
u might want to check the ECU and see what code it spits out; it might give u a clue about whats wrong. in my case there was no error, just the inability for the air motor to control the air going into the engine.
Since u brought it to the shop and its still broken, chances are hes just milking you for more money (and did he say why it was the back 3 injectors and not the front 3 or why 3 instead of just one; i believe the front 3 are easier to take off so he could charge u more for the back 3 but thats my guess). i suggest u try to figure it out on ur own. my family has never trusted those shops and other relatives got scr**ed by shop ppl. eventually they took it to my dad and got it fixed.
if hes not mechanically inclined and hes a guy, he will be once hes done figuring it out. just keep checking and be suspecious of everything. i just hope the shop guy didnt sabatoge something so u'll come back.
im usually in the 3rd gen thread (thought this thread was in 3rd gen; came here through google) and i asked the same question there (check for "engine stall after injector replacement"). they gave a few good tips to check on.
04-08-2007, 09:07 PM
#25
Donating Maxima.org Member
Join Date: Apr 2007
Posts: 5
Thanks, after I get back in town we will be going over what we can.
making new post as to not clutter up this one for that person, I will edit it for the link for search purposes.
Thanks!
I started my own thread!
making new post as to not clutter up this one for that person, I will edit it for the link for search purposes.
Thanks!
I started my own thread!
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