while i am idling my RPM needle jumps up and down very slightly but quickly. when it does that it idles rough, after a while it will just stop and start idling real smooth again. i think it jumps when i am acelarating lightly to. when i am idling and it starts to do it it almost feels like it will cut off, but lightly though, can anyone help me out on this?

 

I have a very similar issue at idle and while driving but while lightly accelerating it feels more to me to be the clutch slightly disengaging as my pedal is not right where it sits... This however doesn't serve as help for the at idle problem

 

Remove the connector to the MAF and spray the connector terminals with carb cleaner, insert/remove it a couple of times to make sure the contacts are clean. Make sure it's replaced properly. Test. If no difference, clean the IAC.

 

i cleaned the IAC and it still does it, except it does it worst now, do yall think that if i change the MAF it might solve the prob, teh idling is so rough that it almost feel like its going to cut off....

 

Re-adjust the IAC again. You may have turned the wrong way? Also replacing the MAF MAY work, but theres no gaurantee as we have not ruled out any other possible problems.

 

If you really believe it is the MAF, unplug it; you will see a raised RPM value but the car should idle cleanly. I have had MAF connector problems on three Nissans now so I'm inclined to think the MAF connector is prone to bad connections.
Of course the TPS is another possible candidate to look out for.
Before you think about changing anything, clean ALL sensor connectors and make sure they're all properly inserted.

 

not to pirate this thread or anything, but what sensor controls the signal sent to the tachometer? Does the ECU generate a signal from a certain sensor? My tach hasn't worked in a while....the needle jumps all over the place (bounces from redline to 0, reads way too low, and sometimes reads normally) Usually at idle it will read 0, then when I accelerate and cruise along, the needle never goes above 1K. The engine is not affected at all. Any suggestions?

 

^^^funny... lol

 

i had have a similar problem with my 97 Max starting about October of last year. Similar to what you guys have described with the rough idle, when I put the gear shifter from D to N or to P, the idle shot up to 1300-1500, which is really high considering that the idle should be about 750 +/- 50. It really baffled me for quite sometime and I did a tune up with new PCV valve, new plugs, new fuel filter, cleaned the throttle body, but still the same problem.

i thought it had to do with the air intake...there is a screw that you can turn either clockwise or counterclockwise that will then bring the idle up or down depending on the amount of air is limited/passed through. From there it worked for me...but my idle is now about 850/900 when everything is warmed up...hope this helps.

 

are you talking about the black looking, plastic screw that located close to the side of the intake manifold close to the fire wall?

 

yes, it is a rather big looking screw and it is a phillips head. have the car idling and turn it clockwise and it should decrease the RPM as that is limiting airflow...

my idle jumped about 200RPMs today because the weather is so cold and the cold air is thick. I am thinking that is the case, because in warmer climates and temperature, the idling is a normal 800 or so...

give it a try...i was out of ideas and still am....

 

So I tried the uplugging the MAF connector while the car was running... And it(the car) immediately shut off. Does this imply a bad MAF? Or Clean the IACV before jumping to conclusions?

 

Ok, so I've cleaned the MAF connectors(nothing), cleaned the IACV(helped a little) Maybe my air filter needs to be retired... worth a shot. How does one go about testing for a faulty TPS?

 

cams? lol

10char

 

well my high idle problem came back again last night...and no resolution with the adjustment of air intake...it is at the minimal...so I turned off the car and restarted it and the idle was back to normal...

I also reposted a note in the general forum to see if anyone else may be experiencing this very similar problem.

http://forums.maxima.org/showthread....94#post4751094

 

Have you checked on TPS (Throttle position sensor)? There is a sticky in the How To's section to test and adjust it. TPS sends signal to ECU to adjust fuel/air mixture. Sending the wrong signal will cause rough idle

 

I am not sure if that is strictly a "running rich" issue...that's why i threw it out there to see if there are other people who may have experienced it and what their diagnosis was for the problem. I am assuming that the jump is due to the leaner mixture. I'll double check the TPS sticky, but I believe that has been looked at during my tune up...

 

Well if you haven't checked the filter, just change it, they are cheap enough. Mine hadn't been changed for 9 years and the car was transformed after changing it, who knows what yours is like?
Follow the recommended link for the TPS; the TPS is just a wirewound potentiometer, a simple device, you might try slackening the screws that hold it on and rotating it slightly one way or the other. They can develop a 'dead spot' due to wear. And you have checked the spark plugs I assume?

 

lucky you! i just solved this exact problem. i replaced my PCV Valve, it was junked, that helped, changed the plugs too, that also helped, but it was still doing it a little bit....then i got a misfire code from my engine, changed the coils and wala! good as new. i did the fuel filter as well but that didnt seem to do much.

also things to check/clean: MAF and throttle body, i checked both on my car, both were spotless, but if they are dirty they may be the cause of the problem.

 

I haven't posted alot at all but I read a bunch of stuff so not quite the noob here. But here is another angle. I had this similar problem when I bought my car from a dealer. LONG story short they replaced just about everything they could and even called in a Nissan guru from California, I am here in Texas. It turned out to be my ignition coils. which I had told them to replace in the first place. Kinda pricey, but you may wanna check those. The jumpy-ness only occurs in idle when the ignition timing is not affected by throttle. Not a mechanic myself but it sounds exactly like my problem and after new coils, [they run around 90-100 a piece] the RPM jumps stopped altogether. Luckily it was done at no cost to me other than waiting a month to get my car. Good luck with that.

 

Well, I'm running a K&N but haven't been able to clean it due to the weather(winter). Spark plugs yes. It hasn't stalled since I cleaned the IACV and opened up the screw ALL the way. The current problem really feels like bad fuel or a cylinder not firing right. Doesn't a bad coil pull a code? I'm not getting any, not even ghost codes. My PCV is pretty new. What about EGR?

 

OH, my idle problem was a too low one. The car would stall when popping in the clutch, was thinking about changing back to my regular crank pulley and taking off the AC

 

how do you check your coils to see if they are bad or not?

 

I recall seeing a thread in the 4th gen forum a week or two ago where someone had a problem with their coil and had similar idling problems. They changed one of the coils and the problem was resolved.

Anyone find the thread? From what I recall it was to pull the coil while the car was idling--and if the idling starts jumps around, then that coil is GOOD but if the idle was not affected, then that coil is BAD...

 

^^i'm wondering if i should try this. i have six extra coils in the garage, i was thinking of them when i first got the problem,
humaras, let me know when you are for sure thats the right way to test them...thanx

 

if you have all six, then replace all six and see if there is a difference. If by replacing all 6 coils you do notice a difference,then you have isolated the problems to to coils...but the further investigate the specific coil would take some "switching" and plug and play. I'll try to find that thread today...

 

The 4th gen maximas have something called an idle air control valve. More then likely, u need a new one.

 

You just replied to a 14 year old thread. Nicely done. :rollseyes: