Alright here's the skinny,

The max just cut off on me the other day when I came to a stop at a traffic light, i cut it back on & watch the rpm needle go up and then come right back down, it didn't stop where it should around 500-700rpm it just went all the way down. The only way I even got the car to move was putting it in Neutral (it's an automatic) starting it back up with my foot slightly on the gas, keeping the rpm around 1000 and putting it in drive, but I can't take my foot off the gas otherwise the car will cut off and wont stay at normal idle. To make matters more interesting, i didn't throw any codes or SES/CEL lights, and just in case it matters i'm in the process of replacing my cat-back that has rusted out i didn't know if that had anything to do with it.

Really need to get this up and running, thanks in advance for your help guys.

 

i dont know much about it but i think spark plugs have an effect on idle speed?

 

i was thinking that might be it, i've had the plugs for at least the past 45,000 miles so I might need to change them out and put in new ones.....But i still didn't think that "bad plugs" would kill my idle, maybe the AAC valve is bad?....any other opinions/suggestions? Anyone else have this problem before?

 

First thing I would check is for a vacuum leak of some type. See if any of the hoses have fallen off or are cracked. Next place to check would be the throttle body. If the butterfly valve was was gummed up with a lot of crap there may be idle issues. Other than that, Maybe someone with a 2k-2k1 can help.

 

i have a question to this thread, i just replaced my spark plugs and cleaned the throttle body
and now my car idles around 900-1000
wondering how to reudce the idle? plz help

 

do the idle re learn procedure... http://forums.maxima.org/showthread....83#post4511883


and as for the original thread, how do u know its not the maf, sounds very much like the maf. if not i also recomend cheking all the vacume hoses, and clean the tb if u never did before. other thing it can be is your tps.

 

For the original poster... If its not your MAF (make sure it isnt), if its not your spark plugs (which it prolly isnt), then I'd turn my attention to your "catback". You didnt include any info so I'll assume that your building it from seperate parts rather than purchasing a more costly complete and tuned system. I took the same path, but beware. You may have heard that backpressure is "bad" for performance, but you may have been misinformed with an exaggeration. The cylinders need "some" backpressure to stabilize their motion, and keep them from losing all momentum when the gas cuts. If your entire exhaust is 2.5", I suggest you swap that B-pipe for a 2.25", either that or get more power out of the engine without taking it from the exhaust.

P.S. After installing my str8-thru cat, B-pipe, and str8-thru muffler I noticed my idle dropped from around 800-900rpm to about 500-600rpm. Less backpressure equals lower idle.

 

you are corect about the back pressure, however id highly doublt in thsi case back pressure is the problem. you would have to go way beyond 2.5, maybe 2.75 or even 3 inch exhaust to notice a difference, besides that the y pipe stays the same diameter. i would think what stabalized the motion of the engine is the constant air/fuel ignition, because once u cut the gas, as u say, the engine stops. id bet his problem has nothing do with his exhaust.