240SX RUNNING ROUGH

[240sxRAGTOP]

HI ALL,
I HAVE A 240 SX 4CYL THAT HAS AN ISSUE. HOPE SOMEONE HAS A SUGGESTION.

MOST OF THE TIME IT SEEMS TO RUN FAIRLY WELL BUT EVERY NOW AND THEN WHEN I STOP( SUCH AS AT A STOP SIGN) IT WILL STUMBLE AND THE RPMS WILL DROP SO LOW THAT IT ALMOST STALLS. I ALSO NOTICE A SMELL THAT MAKES ME THINK THAT IS RUNNING TOO RICH.? THE OUTSIDE TEMP DOESN'T SEEM TO BE A FACTOR.

THANKS
MIKE

[sx moneypit]

First off , welcome to NICO!
On your driveability problem you could possibly have a bad MAF sensor or a problem with your IACV. Does the check engine light come on when it happens?

[schroder]

When I was trying to figure out my most recent problem I came across similar issues. Does the idle fluctuate after they come back up, or do they drop and then climb, and continue to do so? It could be something along the lines of your IAA/ACC/Air Regulator. Check your plugs as well. Vacuum leaks could also be a factor too, but that usually causes more of a lean condition on NA motors than a rich condition.

[240sxRAGTOP]

Thanks for your quick replies. No, I don't get any warning lights( such as "check eng") that come on when it acts up. When I am stopped the rpms drop and it almost stalls and it will speed up slightly then fall back. Once I take my foot off brake and push the gas pedal it studders briefly then accelerates fairly smoothly. I only notice the problem when Im at a dead stop. Is there a way to bypass the IAA/ACC/air regulator to see if it is the cause of the problem? Also, where is the air regulator located?
Thanks, Mike

[allenms240]

IACV is on the back of the head, on the intake side closest to your firewall. It's rather a PITA to get to because little room to reach back there. If you bybass it (unplug it), the car won't idle at all; it will just die. There really is no way to test it other than getting back there, taking it off, taking it apart, and cleaning with with brake cleaner. Then reinstall and reset idle (since you took it apart, the idle will be wack until you re tune it using the adjusting screw).

I had the same problem with idling low when coming to a stop. But mine just went away one day.

[Dimitri]

Most ikely it's the rubber boot that connects the the intake manifold. You can't see the hole/crack until you take it apart and bend it.

[Dimitri]

Also take a look here: 89-240sx-rough-idle-t426825.html