rough idling, odd shaking when pressing or letting off gas pedal

[theboy419]

hi, i'm a lil new here so sorry if i'm doing this wrong, but i have a '90 SOHC 240sx. Only real mod so far is an injen shortram w/ (i assume?) K&N filter(or whatever it is they throw w/ those things, lemme know if ya know lol). I know it's kinda sad that i have a 240 and am not doing much work to it yet, but money's been the issue thus far lol.. anyway. Just as i got my car back from a month of being in the shop for what turned out to just be a short in the alternator, i got the car back and it has slowly been getting worse in power and such. When idling, it no longer just idles at 700 like it used to(occasionally it would spike 1000 briefly then fall to 700 nicely). Now it idles closer to 600-650 and occasionally stays stuck at 1500 or slightly lower, varies time to time. I also have noticed something else getting worse. I assumed it's just the injection delay or something, being non-sequential, but when I either let off the gas pedal or press it, the car for a lil while almost violently shakes like you're shifting wrong, but, well, it's already been in gear for some time so it's not related to that. I'm not sure if anyone has any ideas/suggestions as to what it might be and how to fix it? I read an article about the AIV but be darned if i can figure out where it is, how to clean it, etc. Was debating if maybe it's the PCV valve, but again, not positive. If anyone could help, I'd greatly appreciate it, thanks!--theboy4191990 Nissan 240sx SOHCInjen Short Ram IntakeBosch Platinum 4 plugshttp://www.xethron.com/240sx/new/

[s13sr20chris]

welcome to nico bro. ok, step one is get rid of the bosch platinum plugs and get some plain jane cheap ngk plugs. they are the best for your nissan. next try the wiggle test on all parts of the harness you can get your hands on to see if she stumbles. then you want to spray the whole intake system up to the head with carb cleaner and see if the idle changes.

those are just some preliminarys.

[theboy419]

about the NGKs... i was suggested them a while back when i first needed to change plugs, but a friend insisted on atleast trying the bosch...and i gotta admit, they are the most powerful sparks i've ever used, so why switch to the NGKs exactly? as for the carb cleaner, i was reading a lil bit around and have found some people saying to use brake cleaner instead, doesn't leave a residue, any thoughts? thanks!

[nismo240sxer]

Hi man I got the same problems on mine.. did you find a solution?

[InsanityInc]

about the NGKs... i was suggested them a while back when i first needed to change plugs, but a friend insisted on atleast trying the bosch...and i gotta admit, they are the most powerful sparks i've ever used, so why switch to the NGKs exactly? as for the carb cleaner, i was reading a lil bit around and have found some people saying to use brake cleaner instead, doesn't leave a residue, any thoughts? thanks!

Use NGKs because the engine was designed to run with them in it. Brighter/bigger spark does not equal a better plug. I've never heard of bosch plugs working well in anything non-euro.