RPM Fluctuation and Shudder

[Nethervue]

Hey guys,
Lately, especially in cold weather, when I come to a stop and have my foot on the brake, the car will give a quick shudder and the rpms drop....it will do this every 10 seconds or so. Also I am noticing it takes 10-15 seconds for the fan and rear defogger to kick in when I start it in the morning. The fan works, but even on full speed, it takes a few seconds for it to kick in to high speed mode.

Sounds to me like something electrical...altenator maybe? When it does the shudder thing, at night I can see that the headlights dim as well. The shudder only lasts for a second or so.

I have a 2001 2.4 4 door silver Alero.

Any input would be appreciated!

[tofast4u2catch]

Before you go and have the alternator replaced (which is major bucks) have your fuel system inspected. My 2.4 used to do the same until I replaced the TPS. Also, if you are having problems with it hesitating in the morning, check the TSB. These cars are known for their engine management problems. Good luck.

[Nethervue]

Originally Posted by tofast4u2catch

Also, if you are having problems with it hesitating in the morning, check the TSB. These cars are known for their engine management problems. Good luck.

Whats a TSB? Is there a service bulletin or did you mean TPS like you mentioned before? Actually, I thought there was a service bulletin for the TPS but I checked http://www.alldata.com/TSB/43/014346GK.html and couldn't find one.

[tofast4u2catch]

Originally Posted by Nethervue

Whats a TSB? Is there a service bulletin or did you mean TPS like you mentioned before? Actually, I thought there was a service bulletin for the TPS but I checked http://www.alldata.com/TSB/43/014346GK.html and couldn't find one.

There is or used to be a service bulletin on the TPS. I'm not sure anymore but I do remember there being something said about it. Sorry for the confusion. I replaced my TPS and things did get much better but I still have the cold hesitation. I just let it warm up a little longer now. I'll check to see if any of the bulletins have changed or have disappeared. I've noticed quite a few things have changed since the last Alero rolled off the assembly line.

[Tilimiritryamdia]

I have same problem with 2001 2.4 Alero . It looks like injection problem ,but I am not sure.
One visit to dealership costs me 200$ , but the problem still exists.... Does anyone know what is it?
Thank you

[Nethervue]

Originally Posted by Tilimiritryamdia

I have same problem with 2001 2.4 Alero . It looks like injection problem ,but I am not sure.
One visit to dealership costs me 200$ , but the problem still exists.... Does anyone know what is it?
Thank you

Hi,
In my case, it was the coil pack. If you are having the same issues as I was having, try starting there. They could see on the coil where it was misfiring. Once that was replaced, not more shuddering!! BTW, no codes were registering misfires.

...since they already have the coil pack off, may as well chuck in new plugs. I put in NGK Iridiums IX.

[SlipShift]

I have an 01 alero and had the exact same problem I have discovered that part of the coil pack arcs to the engine this is an extremely common problem

[Tilimiritryamdia]

Thanks to Nethervue and SlipShift. I'll check the the coil pack.

[undersc0re]

I had the same issue with the coil packs on my 2001 2.4 5 spd alero, the coil pack housing was shorting at about 30,000 km, took the young mechanic many tries and many testdrives with me to say to me quit driving like a grandma and rev it up like this and he drove averaging about 4500 rpm which of course pissed me off because the abnormal misfire happend when I gave just a wee bit of gas at mostly lower rpms, so anyways got the head tech guy to take it out and he knew right away it was ignition related and no codes were showing up on the decice they were watching while driving, even though he was sure it was ignition related my car was there for 2 and a half days! Thankgod they gave me a loaner, they reflashed some memory in my car which fixed most of the stumbling problem I was having whether the stumbling issue had to do with the coil packs or not I have no idea as this memory was flashed at the same time the coil packs were replaced, to this day though I get the very odd stumble cold or hot....of course I have replaced a hub assembly (bad wheel bearing) at 62,000 km, and my blower motor resistor is screwed, and I have replaced my brakes once so far, other than that smooth sailing, knock on wood.
Oh ya one more thing I got them to fix was a tinny rattle in my tranny at certain rpm's when the car was hot in the summer usually, they put different oil in it, and put the oil level a little higher than normal and the sound never came back!