1995 Buick Lesabre

[marlin70]

I have posted this in another site but did not get any response.

I have a '95 Lesabre that when it is cold it will not run correctly. I can crank it and it runs perfectly in park and when I put it in drive it starts sputtering but will not rev up or go. I can put it back into park and it still does the same thing. I can turn it off and recrank it and as long as it is in park runs perfectly as above but put it in drive it will not go. I can let it run in park after a recrank until it has warmed and it runs ok from then on. Could someone direct me to the cause?

[HotZ28]

You might want to check the coolant temp sensor (CTS). The CTS sensor tells the computer what the operating temperature of the engine is. When the engine is cold, it needs more fuel to operate correctly, especially under load, (in gear) and if it is cold enough, it will inject a large quantity of fuel to help start the car and maintain idle in gear. This function is called "Cold Start Enrichment" and replaces the function of a choke. The best way to check the function of the CTS is with a scanner, however if you don't have access to one, you can check voltage, or resistance.

The sensor is simply a thermosistor; as the coolant temp gets higher the resistance drops. The ECM supplies the sensor +5V and measures the voltage drop through the thermosistor to determine temperature. Some resistance vs temperature values follow:

*F--------Ohms
210----------177
158----------467
104----------1459
68------------3520
32------------9420
-4-------------28680
-40-----------100,700

The sensor is used for open/closed loop operation and is used in the calculation for fuel and ignition.

[marlin70]

Thanks for the info. Sounds like what it may be.
Now, would you be so kind to tell me just where I may find this sensor? I have looked the internet over but have not found the location.
Thanks again.
Marlin70

[HotZ28]

Drivers side, end of intake manifold, under throttle-body 2-wire sensor

[marlin70]

Thanks for the info. I will check this out this weekend.
Landon

[Blue Bowtie]

Originally Posted by marlin70

I have posted this in another site but did not get any response.

Well, THAT was a silly thing to do. At least you finally found the right place.

The resistances given are correct, but if you want a little more resolution:



Find the sensor with yellow and black wires attached, and you should have the CTS.

Another possible cause of your symptoms is a medium vacuum leak. The vacuum connections at the TB, PCV, and power brake booster might be causes.

There may also be a sluggish or non-responsive IAC, and/or the TB and IAC air passages could be restricted.