Tach dips way below idle, stalls, when coming to stop

[Shmackey]

Hi all, long time no see.

So. My 2000 GXE (B15 5-speed, 105k miles, perfect maintenance) recently developed this problem. It starts fine, drives along just great, and then when I come to a stop the tach doesn't stop on its way down from driving speed. It should go from 3000 (for example) to 750, but it just keeps going down, past idle speed, and either bogs hard and recovers or totally stalls. It doesn't do it all the time, but when it's doing it, it does it consistently for that period. I'll be tooling along and come up to a light. I either push in the clutch all the way or shift into neutral--it doesn't matter which--and as I press the brake the tach just keeps dropping, as if the engine speed were still coupled to the car speed even though it's not. I can reproduce it right after it happens: shift into neutral, put the parking brake on, and when I rev the engine and let off the gas, the tach just keeps going down past idle. It's almost like it builds up some momentum: if I rev it pretty high and let off, it seems to drop even more.

This was just an annoyance until it started doing it more frequently and more harshly, to the point of real stalls. Driving in the winter like this is not an option, as I would like to be able to use my brakes and steer when I come to a stop....

Anyone know what's up? I see some posts about this in the newsgroups but no real answers.

Thanks,
Greg

[JerodKing]

It sounds like a common problem on GA16DE engines, but I'm not sure if it is the right thing for your car. Look into cleaning the IACV (Idle Air Control Valve). Alot of times they get gunked up with carbon that they don't function properly.

[bigdaddygnar]

i have a 2000 gxe as well, and i had the same problem. i took it to my mechanic, they said it was the idle control motor. they replaced it, but soon enough the problem came back. so they cleaned the maf and o2 sensors, and it helped a bit, but every once in a while it'd dip below 800 rpm. recently i replaced the battery and it hasn't stalled since. it had the original battery until a couple weeks ago and it runs fine now. not sure if that'll help, but it worked for my car. good luck.

[Shmackey]

Originally Posted by bigdaddygnar

i have a 2000 gxe as well, and i had the same problem. i took it to my mechanic, they said it was the idle control motor. they replaced it, but soon enough the problem came back. so they cleaned the maf and o2 sensors, and it helped a bit, but every once in a while it'd dip below 800 rpm. recently i replaced the battery and it hasn't stalled since. it had the original battery until a couple weeks ago and it runs fine now. not sure if that'll help, but it worked for my car. good luck.

What'd it run you to replace the idle control motor?

[bigdaddygnar]

i can't remember exactly. i'm gonna say 200-300. i just remember being rather angry when i heard it was a couple hundred dollars for something so simple.

[PiotrJ]

Originally Posted by bigdaddygnar

i can't remember exactly. i'm gonna say 200-300. i just remember being rather angry when i heard it was a couple hundred dollars for something so simple.

Just replaced the Idle Air Control valve in my 2001 GXE with the same problem (that's what they call idle motor). Cost me $360 with extra 2 hrs trying to diagnose the problem. IAC works, but the car stalls anyway.
Mechanic gave up and disconnected the actuator that supports the throttle and prevents sticking after the engine shut off (little plunger retracts after engine warms up, so that while runnung, the throttle at idle is controlled by ECM). So, the car does not stall, but the problem persists anyway. Nissan Dealer got snutty with me and claimed this is a very uncommon problem with Sentras. Well, this is the tenth post with the same identical problem. Oh, the fuel pressure and the voltage were checked along with MAF and ECM and everything works OK.
hrottle body was replaced with the IAC. If ANYONE has any ideas, please let me know

[bigdaddygnar]

ha, my car is back to stalling every once in a while now. i noticed on my friends' cars that they idle lower once they put an aftermarket exhaust on, but they don't stall like mine. it's quite frustrating.

[crazyhorse06]

you can try the throttle positioning sensor or the maf. to stop it from stalling without doing that just up your idle a little.