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View Full Version : Vacuum/Idle issues on new car


hobag
05-02-2010, 10:33 AM
I picked up a 1995 240sx that wasnt running for a good price and got it running but there appear to be some idle/vacuum issues with it....

When i first got it, it would not idle at all. I removed the IAC and cleaned out all the crap and it idles now BUT you have to give it a bit of gas on cold start and its runs real real bad for about 10 sec and then smothes out and will idle liek that till warm.

Once warm idle drops down in the 600rpm and lower mark until it stalls.

Havign said all this it runs real good when driving and has plently of go.


Things ive done so far:
Checked compression (180psi on all 4)

Checked plugs and wires (very black and running rich according to plugs and number 4 was worse so i replaced the injector and there all the same now). Has nology hotwires which i dont like btu seams to have plenty of spark.

Removed all emissions equipment (egr is blocked off and removed all vac lines as well. Evap pruge as vacuum line removed but still installed. Now removing all this made the care feel smoother but didnt change idle.


Now i cant seam to find any vacuum leaks but as a test i induced a large vacuum leak between the tb and maf and the car didnt change how it idled at all. Unpliging the maf and the car dies. CTS sensor and TPS both look good according to scan tool.

ON the intake hose before the throttle body there are 3 niipples. The one neasest the tb look to be looked back to the iacv line. Valve cover is vented via a filter and the 2 points on the intake tube are blocked off.

If there are 3 ports on the intake tube and i can only account for 2 what is the 3rd smaller tube for?



If anyone has any idea what can be causing this please let me know. Im not going any further with this car until i can get it running and idleing properly.


OH btw i checked cam timing and it doesnt look anything near what i can find for an s14 but if it were off that much it wouldnt run at all. (car does lope a bit like it is camed though)

heyitzalan
05-02-2010, 10:51 AM
i have the same problem, brother. the valve cover needs air from the intake chamber, put the hose back in. it will runs back to normal.

and i have 3 ports under the throttle body blocked off with a vacuum cap. but i'm not sure if i have the block off this port on the throttle body that goes back to the intake manifold somewhere.

hobag
05-03-2010, 06:22 AM
i have the same problem, brother. the valve cover needs air from the intake chamber, put the hose back in. it will runs back to normal.

and i have 3 ports under the throttle body blocked off with a vacuum cap. but i'm not sure if i have the block off this port on the throttle body that goes back to the intake manifold somewhere.

I though about that but then again the guys running around boosted have this vented and they can still idle as well....

I think there is something else going on however i am going to pick up some heater hose and hook all that back up properly.

hobag
05-04-2010, 07:02 AM
Well an update:

Routed the valve cover back into the intake tract and cleaned the pcv valve..

The car will now start and stay running without having to hit the gas but once warm it idles a little low and lopes real bad like its camed...

Its a contstand lope, doesnt really change, isnt there when its cold only when warmed up and trying to idle.....Any other ideas?