240sx hard idle and then bog out.

[GreenKryptonite]

i used to have a competly stock 89 sohc fastback and when it bogged out i found out it was the coolant temp sensor. now i have a 95 240sx SE. And it seems to have the same problem. But i have replaced the sensor and it still bogs and idles low (400rpm or lower). It doesnt seem to have a problem as bad if i keep my A/C on. But sometimes it doesnt matter at all ill come to a stop sign or light and my car will drop rpms and bogs. All i have for my car is a earth kit (dont know why i wasted the money) and a Injen Intake (short ram). new sensor, checked the ohms with the sensor connector and it all checked out as does the sensor. i pulled the codes and all i got was the knock sensor which happens when my engine stalls. cleared all codes and got a 55. O2 sensor also ok. Intake checked for leaks but found none. im stumped and i've searched.

[boostme]

Ya know, it could be so many things but I'd start with the basics. Does it run rough or miss at idle? You could try a power balance test on it to see if one cylinder isn't contributing as much at idle as the others. Aside from that you'll need to figure out if you have a lean or rich condition to check out the car further. I have a intake leak on my 240 and didn't find it till this week and have had the thing for over a month knowing there was a problem. A sure way of telling if you have a vacuum leak or skewed lean fuel alpha is to remove the oil cap while the car's running. If it tries to die or almost dies you got a leak.

[GreenKryptonite]

actually i have taken off the oil kap and it did not bog. its random when it does it. but once it bogs it will bog for about the next 15 mins. it may be the fuel.. due to all the hurricanes down here gas stations are emptying all there gas and refilling so often. maybe just bad gas.

[Projex240]

If you took the oil cap off and it didnt bog any worse--it sounds like a vacuum leak. The oil cap relaeses pressure when cranked that should noramlly be either capped off from the large vac line from under the TB to the intake pipe.It could be a vaccum leak or a aic valve problem--or the idle needs to be adjusted

[GreenKryptonite]

as of today i did take off the oil cap (i havent done this about a month.) and it did start to die. also i overheated last night. but this i believe is due to me recently replacing the radiator and not getting all of the air out of the system, because it would over heat and then go back to reg temps. i am also replacing the sensor (coolant temp) again.