1992 Grand Prix 3.1 Help Please

[educated_rage]

I have a 1992 Grand Prix with a 3.1 liter engine, the issues i have had the last couple days, is it studders when driving like it is not getting gas, it does not stall but you can feel the difference as if it wanted to chug a little, not enought to stall but annoying none the less, is this a oxygen sensor or throttle sensor, if so where are they located respectively. also the speedometer is now working incorrectly, bounces around all over the place well below the speed i am going, is this another sensor or a fitting on the transmission ?, I am new to this please bear with, Thanks so much !

[Hungrycat7]

I would say the sputtering could be many things! Could be an O2 sensor or a dirty EGR valve. Also when is the last time you had a tune up done? Fuel filter, plugs, wires, etc.?

[GTP Dad]

Welcome to AF!!

There are several possibilities based on what you posted. First, when was the last time the plugs and wires were changed? If it has been a while you may want to change them. Second do you have a Check engine light? If not I would rule out the O2 sensor. However, I would change the fuel filter to make sure you are getting good fuel flow. Then I would check the fuel pressure at the rail to make sure the pressure is adequate. It is possible that the fuel pressure regulator is going bad and there isn't enough fuel pressure to keep the engine running. The other possibility is a bad fuel pump but that is doubtful.

The throttle position sensor is located on the side of the throttle body and is not hard to get to. This sensor could be bad since there is a stumbling issue. It is not that hard to change on these cars. The EGR is also easy to get to and sometimes it will get dirty and not work properly. You can clean it by removing it and spraying it with throttle body cleaner. The passageways also may need to be cleaned as they plug up easily.

As for the speedometer the speed sensor on the transmission is probably bad and causing it to bounce. Because the computer uses the speed sensor for various functions, I would change it first to see if the stumbling goes away. I have seen it cause numerous issues.

I hope this helps you out!