Not much of a mechanic and i have a couple of problems. First, my bonneville was running fine till the timing chain broke. After replacing it the catalytic converter was plugged (with gas i'm sure) and was cut out.(was cherry red). I now have a check engine light on, the engine revs high when i start it then idles down as it warms and she likes to get hot, about 3/4 on the temp gauge, the goes down and goes back up and down and up. I've replaced the thermostat twice and still the same thing. I know that is alot to ask but i'm looking for some help. Don't want to loose my bonneville. She only has 94,000 miles. And no, i haven't put a converter back on her....could that be part or my problem?? Any help will be appreciated.

I need to make a 1200 mile trip in her in the near future. Thanks.

I doubt the cat would have an effect on your idle. Especially since its out of the equation. Your up and down idle could be your IAC valve, or a vacuum leak. Have you done the paperclip thing on your diagnostic port to check for codes?

not sure how to do the paper clip test. can you elaborate?? do i have to have the converter at all?? AIC valve....where would i locate it and i guess just have to track down the vaccum lines??

No, I believe your PCM does not monitor emissions after your cat. Unless you just happen to see an O2 sensor after it, but I doubt it.

Code check...
Have a pen and paper ready. It helps to be in a dark area to see the check engine light because you have to count how many times it flashes.
Find your diagnostic port, usually below the knee panel under the steering wheel.
Take a paper clip and jump pins A and B
Turn your ignition to power on. DO NOT START IT.
Your first code should be 12 I believe. This is the code for that everything is working.


Now count the rest of them and get back to us.

Getting the codes will help us help you.

Check for vacuum leaks.

Sounds like you have air in your cooling system. That'* why the temp goes up and down.

What about his water pump Dan, could lack of fluid movement cause something like his condition. Like, lack of pump vanes?

I would expect lack of coolant movement would get hot and stay hot.

Gotcha Dan.

The cooling system needs to be burped. There'* air in there!

I'll work on getting the codes in the morning. "BURP" the cooling system?? Damn i feel really dumb. How would i go about doing that. I thank all of you for the help!!!!