Not that long ago the car was having some serious electrical gremlins, so I finally pinpointed it to the memory chip socket in the ECM having bad contacts... replaced the ECM, good to go. Other things replaced along the way were the wires, plugs, fuel filter, crank sensor and air filter. The car ran great after that, but recently it started acting up again. The symptoms are as follows:

Some time ago, the speedometer would go all the way to about 120mph when you would be sitting at a stop light. This happened for quite some time, but the car had no issues, so it was ignored. Now, as soon as that problem disappeared, the car has a lack of power and a stumble to it after it shifts into overdrive. Today, I barely got the car to start after some hard cranking and a lot of sputtering.... it'* about 0* outside right now.

I checked the coils... secondaries read as follows:
plug 1-4: 11.23
plug 2-5: 11.73
plug 3-6: 11.67

I checked the fuel pressure earlier... IIRC, the readings were about 30psi, and 35psi when I would goose the throttle.

Just searching for clues, as I'm working outside and it'* PAINFULLY cold here

Please drop some knowledge on me if you could!

Fuel pressure looks low, IIRC it should be above 40.

Are your coil posts all on one side or staggered side to side?

The speedo thing is likely unrelated and may be the VSS is acting up. It'* near the tranny output on the passenger side.

The coil posts are staggered side-to-side... I'll sneak outside in a minute here and recheck the fuel pressure.

BTW-where are the coolant temp and air temp sensors located on this particular 3800 engine?

One CTS is behind and below the throttle body. The other is... on one end of the LIM, I can't remember if it'* hiding below the TB or on the other end. The intake air temp sensor is on the back side of the air box below the accordian tube.

I just rechecked the pressure, it reads 35psi at idle and 40psi when the throttle is goosed.

You need 42psi at idle. Worn fuel pump?

This is a possibility.

The 7psi differential at idle is enough to cause stumbling and driveability issues?


btw-I checked both temp sensors and on the black wire of each I started out with about 31.7(or 3170), slowly moving down to 30.5(or 3050) on each as the car warmed up some. This is starting out with the car somewhat warm already. I cannot get an ohm reading off the yellow wires of these two sensors, so is it safe to say that wire is a 5 volt input from the ECM?

Definatly. I had 38 or 39 and had problems.

Fuel filter change first, just to be sure?