Hed5150

when i start my car in morning (or after its been sitting for like 6hrs) you need to give it gas around 2000rpm for about 10 seconds otherwise it would die right away. then once running if you do not let it warm up it will die if you put it in D,1,2 or R (nuetral won't stall). then once you get it goin if it is not completely warm, when you come to a stop as you slow down the rpm start trying to die, it will violently jerk untill it stalls or corrects itself. like a clutch when you stall)but this is an automatic tran though. My ECU is telling me i have a bad Engine coolant temp. sensor, speed sensor, and knock sensor. The starter was replace this month. any ideas guys?
PLEASE help

g9s0x

the speed sensor is what is causing your car to stall when coming to a stop. these are all similar on different makes of cars and i know from my experience with DSM's that the idles speed control sensor (or speed sensor in your case) helps the ECU maintain the correct idle speed. if this sensor is unable to supply the ECU with sufficient data through voltage readings, the ECU cannot maintain the proper idle speed and your car will stall when coming to stop.

a bad coolant temp sensor will make your coolant temp gauge have no reading, or a false reading if it is still functioning, but poorly. what is the status of your coolant temp gauge when driving?

as for the knock sensor, i am not too sure as to why it would throw a knock sensor code. it is possible that the knock sensor has gone bad, but the 4g maxima is not an old car at all...possible due to throwing one of the aforementioned codes (most likely the speed sensor code). when your car experiences knock, the ECU pulls timing to prevent engine damage...maybe this is due to the cars stumbling when coming to idle...but like i said i am not too sure on this one.

hope this insight can be useful. good luck. just helped a friend fix his 99 maxima tonight. threw a 0102 code for the MAF sensor...poor guy was trying to install his cone intake filter and messed with the MAF sensor and in doing so broke the soldered prongs inside the senor housing causing the car to stall when the throttle plate was opened. luckily i was able to bend them back so that a connection was sustained. let me know how your car turns out.

g9s0x

how many long pulses/short pulses did the CEL throw when you were tapping the ECU for the error codes? just want to make sure you are looking at the correct codes. nothing worse than diagnosing something that isn't the problem...been there, done that! just tryingo to save you the headache.

KINGMAX

Ok, the last info that was posted is not right. Your problem is most definatly the IACV( Idle Air Control Valve) when it is cold it is hard to keep the car from stalling without giving it some gas, but when it is warm it runs ok. The speed sensor is what helps calibrate the speedometer, there are 4 of them on a third gen. not sure about ours(will have to check the haynes manual which my friend has). The knock sensor causes "bumpy" acceleration and loss of performance, changing this will not solve your stalling probs. Unless you have an Automatic( bad torque converter can cause a stall when you shift into any gear) it sounds like you need a new IAC valve.

g9s0x

he is correct. i should not have boldly stated that it WAS your speed sensor because as i was sayin it was most likely the idle speed control valve or in this case the idle air control valve (IACV). i was simply stating that it was probably due to this valve as KINGMAX specified, but didn't make myself clear. thanks for the clarification though and i do stand corrected.

njmaxseltd

iTrader: (19)

Change your Engine Coolant Temp Sensor, that should correct your idle problem. The ECU can't tell what temperature the engine is running at which is most likely the cause of your stalling. Don't touch anything else (IACV) until you get that sensor replaced!

The speed sensor might be bad too, but I wouldn't replace it just yet give it another shot. Reset the ECU after you replace the Engine Coolant temp sensor and see if the Speed Sensor comes back, If it does, replace it.

The KS code should go away with the new Temp Sensor.

NOTE: There are 2 coolant temp sensors. One is for the gauge inside your car, the other is used by the ECU to determine engine temp. The sensor you want is the one closest to the engine block. Follow the upper radiator hose and you'll find the two of them.

Good luck
Tom