i just recently started having problems with my 01 bonneville ssei. i took a trip from wisconsin to north carolina and it seems like its not running right. every once in a while when comming to a stop it will idle down like normal, then all of the sudden drop about 150 rpm and the oil guage will also drop and the car will shutter for a second, then pick back up and idle normal. i dont know where to start looking for problems. ive had diesel trucks my whole life and this car is completely different. since ive bought the car ive had the check engine light come on twice and when i scanned it it was a o2 sensor low voltage code. it seems like the car does not have as much power as it did but im not positive, just feels like it. also does anyone know where i can get center caps chea? i lost two of the solid chrome ones with the raised hex in the middle this winter. do yall think my problem is just an o2 sensor? also it seems to be using quite a bit of coolant. ive had the car for a couple months now. any thing helps

thanks
-Justin

First Id like to say welcome to the forum and thanks for joining us

Second... do you still have a check engine light on? if so... you might want to have it scanned again to make sure that over the course of the trip something didnt fail or start to fail to cause your current problem

if its not on, then you might want to consider looking at having the 02 sensor replaced because that CAN cause some of the problems your describing... not that it WILL fix them but you mentioned it had the code in the past and it might be the reason for your problems... or have a shop run a diagnostic check and see if they can find a problem with anything... either would cost lol

Dealership costs... O2 sensor, on crossover pipe - 146.14 +tax ... post cat - 162.74 +tax
diagnostics usually run around $75-100... so its up to you and your wallet

Sounds like our TPS might be the problem. https://www.gmforum.com/t279319/ If memory serves your not to far from me. Feel free to join the wisconsin bonneville group here. Pontiac Bonneville Forum - Official home of the Pontiac Bonneville Club. - Wisconsin area Bonnevilles We also have a Wisconsin meet coming up in a few weeks. https://www.gmforum.com/t279314-5/#post1368820 Might be a good time to get things done on your car.

Don't worry about the SES light, that'* because your RPMs dropped to far and that'* also why your oil pressure dropped.

Hi Muktown;

Welcome to the forum!

Please add your year and trim of your vehicle to your signature line. That way when you start asking questions in other areas of the forum, we all have a better idea on how to assist you. Click on "Quick Links" above, go down to "User Control Panel" and then click on "Edit your Signature" It'* pretty straight forward from there.

If you are loosing coolant and you don't see it pooled under your car or visible leaks, that could be a sign that you you have an intake gasket going bad.

thanks for the quick responses. im actually in north carolina right now and the ses came on during the trip and went off again a day later. i will join the wisconsin chapter. i live about 35 minutes south of milwaukee. i will try testing the tps when i get back home. so you dont think any of these problems are serious and i should be ok to drive home without fixing it here?

Just so I'm clear here. The SES light came on when you came to a stop and the RPM dropped. Not when driving. If the engine is running smooth while driving and no SES lights you should be fine. I can't say that with 100% certainty. If you want, changing a TPS is easy and a new one should be under $50.

thanks. i drove home yesterday and it drove fine just every once in a while the rpm dropped at an idle. one thing i did notice is the oil pressure varies quite a bit with the engine in gear at idle say from 30-40 psi, but the guage is constantly moving. is that normal for these cars?

The oil pressure will move a little with RPM. If it'* moving a lot then you may have some corrosion on the plug or a bad oil sender or gauge. Check the connection if it'* moving a lot.