Hesitation then a stall

Ok, new to the forums, but I hope you can help. I have a 2000 GT that is having some issues. After coming to a stop, and I depress the gas pedal, the car hesitates a little, then sometimes the tach will drop out and the trac control on it will shut off, but the car will continue to run for a little while, then it will stall. However, sometimes the car will stall when I depress the gas pedal. Either way, it always results in it stalling. I've already checked the fuel system, my plugs and wires, and think it might be my O2 sensors or my cat. What do you all think?

Welcome to AF.

I doubt the 02 sensors or the CAT convertor is your problem based on your symptoms.

Normally it is two basic areas that cause problems....ignition or fuel. This one sounds more like an ignition related problem. You have symptoms of a flaky crank position sensor.

I agree with bnayor, you have the classic symptoms of a bad crank position sensor.

Ok, so i drilled a hole in the pipe before the cat, and it resolved my stalling issue. So I know I have to replace the cat. Now, on a rare occassion, I get the tach cutting out, followed by the trac control. No hesitation involved, still think it's the crank sensor, and if so, can i replace that without rebuilding the whole engine? :banghead:

Ok, so i drilled a hole in the pipe before the cat, and it resolved my stalling issue. So I know I have to replace the cat. Now, on a rare occassion, I get the tach cutting out, followed by the trac control. No hesitation involved, still think it's the crank sensor, and if so, can i replace that without rebuilding the whole engine? :banghead:

The tach dropping off and the trac off light could still be the crank sensor. The 18X pulse output is probably flaky. Here is a procedure to replace it.

http://mykidz.net/GTP/CrankPosSensor.shtml

Also, get the ignition control module (ICM) checked out since the tach signal outputs the ICM.

It sounds like you have more than one problem but get the CAT convertor tested.

yes, I still believe it's a crank sensor. The harmonic balancer has to be removed (it requires a special tool) but isn't that difficult.

Alright, thanks guys, seems like a pretty easy fix. Thanks for the link. Sensor is pretty inexpensive, so I'll try it and let you know. :)

ok, have you guys ever heard of this situation? Some type of float or flap in the INTAKE failing and dumping antifreeze into the cat to cause it to go bad? I had a muffler shop tell me that might be a cause, but it sounded kinda weird to me.

ok, have you guys ever heard of this situation? Some type of float or flap in the INTAKE failing and dumping antifreeze into the cat to cause it to go bad? I had a muffler shop tell me that might be a cause, but it sounded kinda weird to me.

lol. They were probably referring to the upper intake manifold (plenum) and gasket problems associated with the NA Series II 3800 engine. Do you have any unexplained coolant loss?

Hmm, actually yes, i've been needing to replace a little coolant every once in a while. My low coolant light would come on when I would accelerate and I'd put a little in the resevoir.

Hmm, actually yes, i've been needing to replace a little coolant every once in a while. My low coolant light would come on when I would accelerate and I'd put a little in the resevoir.

That doesn't sound good. Do you see any coolant in the engine oil? You may acutally have a problem with the UIM and/or LIM gaskets. Coolant if unburned through combustion will damage the CAT because it increases the operating temperature causing meltdown.

Nope, none in the oil at all, I change my oil religiously, and have never seen coolant in the oil. In fact, I just changed it after this happened, cause my Change Oil Soon light was on, so while I was under the car drilling the hole in the cat, I went ahead and changed it. :)

Welcome to AF BTW. If there is no coolant in the oil, then the upper intake is most likely the cause of the coolant loss. On a 2000 model, it's most likely the junk gaskets GM uses causing the leak. There is a possibility that the UIM itself is bad, as the EGR stovepipe erodes the coolant passage through the UIM, causing an internal coolant leak or possibly a leak near the seam between the throttle body and UIM. The redesigned UIM used in 99-up 3800's is less prone to this problem, but I've seen them fail as well.