mikesmaximase Posted January 28, 2004 Share Posted January 28, 2004 I have a 95 Pathfinder, I have done plugs, wires, cap, rotor, throttle position sensor (w/ correct ajustment), fuel filter, air filter, oil change, oxygen sensor, pcv valve, new battery grounf wire, new mass air flow sensor ground wire. I also have just done the timing belt and water pump. Mufler and tail pipe. Then timed it. The problem is when the engine gets warm, and Im sitting at the light it will run at about 1000rpms then drop down to 700rpms where its supposed to idle at and then starts to fluctuate a hundred rpms up and down. If I plug in the oxygen sensor it gets worse, so as of now im running with it unplugged. I did reset the computer after the oxygen sensor install. Nothing is coming up in the ECU did all that. The motor is dumping to much gas in as I pulled all the new plugs(bosche platnuim) out the other day and they were black (not oil). So I think thats why when the oxygen sensor is plugged in it reads a high amount of gas and is trying to highly compensate for it and it cant get the correct reading. One of my buddies at work who was a mechanic said it could be the EGR valve, I have never done anything with egr valves before so I dont know if it would make the engine run with dumping alot of gas in and then when the motor heats up and the egr turns on threw vaccum it gets stuck open or something? Any ideas would be greatly appreciated. I have also had a Nissan certified mechanic check over all the elictrical reading from all the sensors and they came back fine. I have not found or heard any vaccum leaks either.???????? Oh, the car only has 75k original miles on it. Link to comment Share on other sites More sharing options...
Blizzardking Posted January 28, 2004 Share Posted January 28, 2004 You could check the rear vacuum hose behind the engine, check that it is well connected at both ports. Although, my rig does do that once in a while; i am to the oint of also belieaving it is EGR related. The only thing keeping me from diagnosing it as so, would be the fact that I have yet to recieve a Check engine light, and no codes come up. Which to my knowledge, is a classic symptom of the EGR being faulty. My Father has a 1997 s-10 Pick-up, with the notorious 4.3l Vortec engine, which is known heavily for having faulty EGR valves, but you would, along with the rpm changes, get a check engine light. Which he has both, check engine light and flucktuating idle speeds. You really dont hear much about Pathfinders, with faulty Egr valves. But at this point I would have to say; Egr valve would probably be the next place to look. Also you did not mention anything about your Cat converter, what kind of shape is it in? Another thing to look at that could also cause this type of issue, would be a LEAKING MANIFOLD . Good luck, and keep us posted on this one. Link to comment Share on other sites More sharing options...
br2an Posted January 28, 2004 Share Posted January 28, 2004 It sounds like you have covered a lot of areas without any luck. When you checked your plugs, were they all fouling (black) or just some of them?? The reason I ask is that a leaking fuel injector (or two) can cause similar problems. However, it would be very unlikely that they would all go bad at once. Brian A Link to comment Share on other sites More sharing options...
mikesmaximase Posted January 28, 2004 Author Share Posted January 28, 2004 the mileage is 75k miles. I did the muffler/tailpipe assembly and checked the screens in the cat and they were all in one piece and not broken. or clogged Link to comment Share on other sites More sharing options...
jjdwyer Posted January 28, 2004 Share Posted January 28, 2004 Hey, Did you happen to check your air intake pipe from the mass airflow sensor to the throttle body? If there is the smallest crack or hole this will cause the problems that you are experiencing. If the air is entering after the mass airflow sensor, the sensor will not no that the extra amount of air is entering the engine and therefore the engines computer will not compensate for it. You will experience a fluttering idle and evenutally it will stall. If you need a quick fix of this just use some duct tape until you purchase a new pipe. Something my automotive teachers in college used to always tell me, look at mechanical basics (air, fuel, spark, compresion) before you look at sensors and electronics. jason Link to comment Share on other sites More sharing options...
k9sar Posted January 28, 2004 Share Posted January 28, 2004 sit at idle with it fluctuating, open your hood and wiggle the connector on top of the mass airflow sensor. Good 'ol Nissan designed this poorly, with the connector on top and the wire coming straight out of the top (as opposed to a 90 degree connector). The result is that the wire from the mass airflow sensor actually hits the underside of the hood and flexes every time you open/close the hood. If that connection is bad, you'r pathy will not run for crud. If wiggling it makes no difference, that's not your problem. Good luck Link to comment Share on other sites More sharing options...
mikesmaximase Posted January 28, 2004 Author Share Posted January 28, 2004 Done that, I took every electrical connection and put electrical grease in it also. I have wiggled every connection with it running and got nothing. Link to comment Share on other sites More sharing options...
Diesel Boy Posted February 4, 2004 Share Posted February 4, 2004 Hey. I was going to say just what jjdwyer said. we get that allot with people with their rally cars. They modify the air box, put on a pod filter, or come back from a stage and the car is fluctuating between 1000rpm and 1300rpm. It is always airflow meter or intake manifold related. The meters are very fragile, the maniflods prone to leeking through vibration, and even a air filter that has moved out of place in the standard air box will cause it. Its the computer confusing its self. The air flow meter is telling the computer that there is not enough air being drawn meaning the motor should be about to stall, so the computer dumps more fuel in to bring up the revs to draw more air, the exhaust sensor then tells the computer the mixture is to rich, so the computer stops pumping fuel through, the revs drop back, then the flow meter says their is not enough air flow so it all happens over and over again. He he, at least thats how i think the order usually goes.................... Pete. -nut- Link to comment Share on other sites More sharing options...
mikesmaximase Posted February 5, 2004 Author Share Posted February 5, 2004 Yeh, I have had the hole thing off looking for rips or cracks, I also made sure the two clamps on each end were tight and air wasnt leaking past. Any other ideas???? Link to comment Share on other sites More sharing options...
Blizzardking Posted February 5, 2004 Share Posted February 5, 2004 I would definately look at the distributor next.................This might be the answer your looking for.............your symptoms are consistant to other problems I have heard of, and it happened to be a bad distributor. At this point, it's worth a try...............Good luck. Link to comment Share on other sites More sharing options...
mikesmaximase Posted February 9, 2004 Author Share Posted February 9, 2004 Ok guys, this s*cks, it went back to my buddy who cannot find anything wrong with it to fix the idle. Checked for intake manifold leaks. He checked all the reading from the sensors again, checked fuel pressure, switched the mass airflor sensor with the one on his truck, it got the same readings from it and didnt change anything with the idle. He has had it hooked up to a computer and nothing came up along with the ecu. he adjusted the base idle and mixture idle and still nothing. He also had another one of his buddies who is also ASE certified and he scratched his head to. luckily this doesnt cost me anything. I guess Im gonna pick up an egr gasket, take off the egr valve and clean it with carb cleaner see if that does anything, maybe it is getting stuck part way????? Im about to give up, and pick up a new car until im out of school and work on it in the summer???? Is there anyway to check the distributor itself??? I have never delt with a bad distributor before other than in a chevy blazer, it had little power and had very hard time starting. -mad- Link to comment Share on other sites More sharing options...
jjdwyer Posted February 9, 2004 Share Posted February 9, 2004 just more thoughts, did it run worse after you did your tune up?? Did you butt connect your ground wire to your mass airflow or did you solder it?? If you butt connected it your asking for trouble because of resistance values will change. 1) When it is running rough are you noticing any black smoke out the tailpipe?? 2) Did you check your idle air control motor??? They also have a tendency to be sticky with age. 3) I have seen ignition coils jump fire from the coil to the block, and cause this problem. And not from the wire, but the coil itself, cracked? 4) A distributor not grounded will cause many funny results. 5) What happens if you put your truck in limp mode or base timing?? Will it run better then? 6) Does your idle increase when you put your a/c on, or turn your steering wheel?? The idle air control motor should bring the idle up a bit. 7) Does your engine turn off fast, like possibly have some bearings done in something say alternator that is putting a load on the engine? 8) Im not sure, is your egr sensor computer controled or vacuum? Possibly stuck, hit it with a hammer before you take it off while idling? 9) Im not sure if you friend did the hammer test or not, but with the engine running lightly tap the MAF, EGR, IAC, with a small hammer and see if things change. 10) Did you check your PCV valve??? 11) If you remove a vacuum hose your idle should increase, does it? 12) You say that this occurs when your engine is at normal temperature, you could be having a computer problem, the pcm doesnt really start adjusting any ratios of fuel until you have reached normal operation temperature. Prior to this, your engine is running on set values and none of your sensors are actually working, Your oxygen sensor will not work until it reaches a certain temp, cant think of the exact temp off the top of my head. Did you replace your O2 sensor with an el' cheapo or a good one? What does your wiring look like tha goes to your 02 sensor?? Coolant temperature sensor also has an important role, it helps adjust the injector pulse width. Is your coolant level low, coolant temp sensors dont read steam, only liquid. 14) Run a jumper from ground to the base of your distributor, and maybe your MAF sensor. Possibly one from your battery to you block as well. 15) Light a match and see how long it takes to burn......... Good luck Jason Link to comment Share on other sites More sharing options...
mikesmaximase Posted February 11, 2004 Author Share Posted February 11, 2004 This thursday Im cleaning the egr valve, and putting a new ditrubutor in it. My buddy said if he was to try and replace something he would do the distributor first). For your question 1) if I have the oxygen sensor plugged in which im running unplugged right now, if i stomp on it it lets out a very litte puff. Reason for it being unplugged is because its worse when plugged in, Its a bosche sensor, I tried one at first and it stil occured after that so then I switched in another brand new bosche and the same thing so i know its not the sensor, plus i have nothing coming up on the ecu. Question 2) yes the idle air control motor was unplugged when it weas idling and it did not change the spuratic idle at all. Question 3) Ill check the coil but i have looked at it running at night and havent noticed anything Qestion 4) its grounded check it. Question 5) dont know how to, let me know please ill check that. Question 6) Yes Question 7) no Question 8) have hit it before while idleing did nothing, im gonna perform the vaccum test before removing. Question 9) did all of it Question 10) pcv valve is new Question 11) Ill check it again, but yes i have done it before and it did change, there is vaccum Question 12) Yeh my buddy told me the second thing to replace would be the ecu, if the distributor doesnt work. I can get them for 100, bucks for the distributor and the ecu for a hundred bucks. But I wanna try one thing at a time. Question 13) Question 14) I have a brand new negative battery cable, Ill check the negative jumper to the dist. see if that does anything. Link to comment Share on other sites More sharing options...
mikesmaximase Posted February 12, 2004 Author Share Posted February 12, 2004 SCREWED UP, my truck is possesed. Now instead of the idle fluctuating during in all gears(park,nuetral,reverse,2,1), its now back to it just in park and nuetral, it ran great all yesturday and today until you put it in park or nuetral, then it did the whole rev up to 2000rpms then down to about 15-1600rpms back and forth. So now it runs great other than this. The exhaust has a gas smell at times???????????????????????????? Why, I love Nissan, but im gonna go back to a Chevy is this sh*t doesnt stop. -mad- -mad- -mad- Link to comment Share on other sites More sharing options...
jjdwyer Posted February 12, 2004 Share Posted February 12, 2004 Take your idle air motor off, unplugging it wont do anything if it is broke. Take a look at it see if it is all carboned up. Move the valve inside then put it back on. See what this does. your maxima may even have the same one........ And have you done anything with your egr valve??? 2.9 litre ford engines have the same problem you are having when either the idle air control motor is dirty restricting movement or siezed, the other thing that causes them to idle up and down is the egr valve sticking? Link to comment Share on other sites More sharing options...
jmcardamone Posted February 12, 2004 Share Posted February 12, 2004 Hi Guys! I got a 87 with the same Problem. I found it was the Valveing system Situated behind the Drivers side headlight. it has some exhaust tubing. I believe this is the EGR system. My was Rotted!. if its Extremely Rusty or its tapping, then that Might be Your Problem. Link to comment Share on other sites More sharing options...
mikesmaximase Posted February 14, 2004 Author Share Posted February 14, 2004 Well, we can count out the mass airlfow sensor, I tried another one and it ran the same way. I took the ecu out and took the plate off and checked the circuit board and its all fine nothing burnt and no corrosion. The egr is functioning as it should, it is freely moving up and down. I have located the air control motor which is in the back of the intake manifold undernieth where the base idle screw is, and its gonna be a pain to get to. But, Im gonna try that and see if there is any carbon build up in there making the valve sticky. The idle air control motor works for air conditioning and power steering. My truck the ac doesnt work, so when its at it lowest idle and I turn the wheel left or right it drops down about 50-100rpms instead of kicking it up a notch. So my guess is its not functioning 100% properly. I just have to wait to order a gasket from the dealership. Anybody ever done one of these before on a Pathfinder. I know on my maxima it is right up front on the side of the intake and really easy to change/clean out. Link to comment Share on other sites More sharing options...
Guest Niko Posted February 15, 2004 Share Posted February 15, 2004 I think I see the key to your problem in what you replaced. I had the same problem and it was the fuel filter. For me,this was the only part I replaced at the time and my Pathy did the same fluctuation immediately after it was installed. The filter was a Puralator...I switched it out for the one that was in there previously(Fram) and PROBLEM SOLVED-it was back to normal! Good Luck-Hope this helps Niko Link to comment Share on other sites More sharing options...
mikesmaximase Posted February 16, 2004 Author Share Posted February 16, 2004 I have a fram in there, i have tested my fuel pressure and its fine. just for hoos and haas today, i took the egr off and both the egr and intake were all junked up with carbon build up. I cleaned the whole mess of junk out of it and replaced the two gaskets. But it still didnt fix my problem. One of my buddies has a scan tool and were gonna try hooking that up to it see if any readings comes out of it. Next step will be getting another distrubutor for it if no codes come up. Link to comment Share on other sites More sharing options...
k9sar Posted February 17, 2004 Share Posted February 17, 2004 If the distributer does not work, I would suggest an exorcism. Your rig obviously has some demons that don't want to leave. Besides the mass airflow sensor I mentioned earlier, the only other problem I have had with my 95 and idle oscillations has been due to a fuel filter (but you've addressed that already). Sorry, but this one has me stumped too. Link to comment Share on other sites More sharing options...
Blizzardking Posted February 17, 2004 Share Posted February 17, 2004 You should probably try PM'ing Jim, He has what you might say, quite a history with distributor problems. If any body hear knows about distributor problems and diagnosis, it would be Jim. Link to comment Share on other sites More sharing options...
MrJim Posted February 18, 2004 Share Posted February 18, 2004 My distributor caused my Pathfinder to stagger and sputter at certain RPMs. It would go into hiding whenever I would take it to the dealer to try to locate the problem. A new (used) distributor took care of the problem. Try Car Parts Dot Com. They have very good prices. Link to comment Share on other sites More sharing options...
mikesmaximase Posted February 22, 2004 Author Share Posted February 22, 2004 OK guys here it is, I disconnected the idle air control motor and it runs fine without it being connected, Just had to turn the base idle up a fraction of a turn. I had taken the bolts out of the intake pleneum so I could angle it up to gain access to the idle air control bolts and hose and taken the idle air control motor off and took it apart and cleaned it, there was no carbon build up in there so I think its just plain old time for a new one. Over 200 bucks form the dealer, or autozone or lappens has them for around 150 bucks. Gotta pick up a power steering pump also, the bearings are starting to go in mine, 140 bucks from autozone, looks like im gonna have to find one from a junk yard. What next? Link to comment Share on other sites More sharing options...
mikesmaximase Posted February 25, 2004 Author Share Posted February 25, 2004 NEVERMIND, still have it unplugged and its still doing it. -mad- Link to comment Share on other sites More sharing options...
88pathoffroad Posted February 25, 2004 Share Posted February 25, 2004 D'oh! Dammit! Mine is starting to give me some real frustrating problems, too. Sputtering when stepping on the gas, overall lack of power, low gas mileage, etc. I like the Chevy 350 idea better and better each time I think about it. Link to comment Share on other sites More sharing options...
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