Rough Idle driving me nuts

[LEMHEAD16]

Guys I need help...

Ever since I bought my 240 it has had a rough Idle. (89 SOHC)

I have replaced the following

Cap 2 timesRotor 2 timesPlugs Wires02 Checked the following

MAFSO2 sensor

Cleaned the following

Throttle body intakeMAFS

I can't think of what else would be causing a rough Idle. The engine has 150 compression across the board.

The engine seems to stumble every couple of seconds as it idles and i am sure that it misses higher in the rev range but I can't feel it. The only other thing I could think of is a dead lifter but I don't really know how to check that. It is a new motor with around 50K on it. I want to get this fixed so I can go turbo. Any Ideas or suggestions you guys have would help

Thanks

[s13EastTN]

Take it to autozone or another store like that and see if they will hook it up too their diagnostic machine for free. That might give you some insight on why it's acting funny.

[LEMHEAD16]

I take to much pride in myself to do that!

[niznos]

You should remove the AIV. They get old and start putting exhaust in the intake and will screw with your idle. This has been discussed many times, you can run a search for AIV on this site and in the 240 tech section, there is also an article in the Nissan article section.

[180fan]

the stumble could be caused by your coolant temp sensor also. Check your idle air control valve, loose MAFS connection, corrosion on the plugs of your injectors or a bad ground too. My SOHC had corrosion on the #2 injector, my SR had a bad MAFS connection and also from what it looks like the coolant temp sensor.

[SunshineAcid]

my guess is its your grounding or your injectors.if youve done something twice you can rule it out as the problem most of the time.and if it was a lifter, youd hear a tapping/ticking when your engine ran. listen to the valve cover. if you can pinpoint a spot you hear a tick (loud enough to hear when the hood is closed) every rotation, it might be a lifter. but then again. ive nursed a car back to health with 3 fallen lifters, and it didnt idle poorly, just lakced power.

[spitz7985]

Go to 240sx.org and click on FAQ, there are a couple of articles on there about idle problems.

[LEMHEAD16]

Thanks for the infoI removed the AIV along time ago, but that didn't help it

I will check the CTS tommorow and see is the helps

What grounding places should I check? All of them?

[Morph]

Dude break down and have it scaned its not that bad it really saves you alot of time and headaches.

[180fan]

pop off your aac and give it the hosing of a lifetime with carb cleaner.

[dj_lennon_franz]

that seems to be a common problem in the KA motors...ive never seen a KA that runs just flat out smooth...one thing i noticed that wasnt mentioned in here...did you check yer motor mounts???? i know on older S13s (zenkis) with the SOHC motor...the engine mounts are usually pretty worn out if theyve never been replaced...i know when i swapped my SR in the right side motor mount on the KA came out in 2 peices (looked alright when the motor was sitting in the car) but DEFFINATLY check yer motor mounts...you may find that one of them is popped and cause unwanted motor shake

does anyone know if the KA motor mounts are softer than the SR mounts??? every KA 240 ive driven always feels like it has REALLY soft mounts compared to my SRs

[Thee 240sx Owner]

ya i replaced mine a while back and it was torn as well as my transmission mount... they suck

[180fan]

Have you checked your injectors by any chance? One of the plugs on my injector #2 were loose and had heavy corrosion so cleaned em up and made the connecters fit tighter. Works very well. Might want to give that a try if it sounds like it's missing.