Well, I recently started noticing my tach bouncing between 40ish and 55ish. Sometimes it will bounce up to 500rpm more in sudden intervals especially when going uphill, but the bounce is usually less pronounced and symptoms can be eliminated with more gas. I understand that the main culprit of this is the valve body, but I was wondering if anything else could be causing this, and if so- exactly what? I do have the resources to replace with a rebuilt valve body, but would it be safer at this point to just start thinking about a full transmission replacement (the transmission seems to shift fine (to me), has almost 130k on it now) if it is the problem?

Thanks for any and all help, I love driving my monte (that's why I've put 10k on it over the past three months) so I'm not shy about addressing the problems even if they're costly, but as I said before any other imput as to possible problems that might be causing these symptoms are welcome and appreciated. Thanks a lot guys.

Check sig for information regarding make/mode/year/etc. All stock.

 

Could this also be my catalytic converter?

 

The cat' would be my 1st guess. Take it to a RELIABLE independent garage and have the cat' pressure tested.

A cheap test is to (when the car is cold) get a similar car, have a friend rev the engine a bit, and put your hand up to the exhaust tip. Feel the pressure coming out? Now do that with your car. Does it have the SAME pressure???
If not, chances are your cat' is bad, ESPECIALLY if it's stock with 130K on the clock.

 

Thanks for the thoughts RocknSS04. I think I know a reliable place where I can bring it and have the cat' checked out, but I probably won't get around to doing that until the weekend just because it's a good 45 minutes away (and with a foot of snow on the ground that's going to be doubled).

 

Before doing anything to your transmission, I would check other things for sure. The CAT is a good place to start. Also, a bad ignition coil could cause this, as well as a bad MAF sensor.

At 130K i'm assuming it has had a tune up with new plugs right?

 

Time for your ZZP Downpipe

 

Yeah I got new plugs and wires, etc when I purchased it 10k ago. So I don't think it could be anything like that. Unless they were defective or something, which I highly doubt. I'll be sure to check out the MAF sensor and stuff. Can you actually clean a MAF sensor like you can some sensors or is that usually not accompanied with failure of the sensor?

As for the ZZP Downpipe hell yeah, oh wait, no. Emissions standards are a killer, but I could just replace things when emissions testing rolls around haha.

 

You can clean an MAF sensor, Its worth a shot. Just be careful not to break those really fine wires.

 

Okay, so I stopped by a mechanics place and the dealership today. Neither of them had any idea how to test a catalytic converter, so I can either get a diagnosis from the dealership for 50 bucks, or just get the cat. I'll probably go with the diagnosis. Another thing I've noticed is my car won't rev above 4k rpm without hesitation. If that's any indication of something specific wrong, feel free to share. Thanks a lot for all your guys's help. I love my monte and what to keep it running on top.

 

Oh also the bounce occurs after shifting into third and fourth gears after the RPMS drop. It bounces and then settles.