Have a 1999 SL2 267,000k, when i am siting at a dead stop cold or all ready hot, it hesitates to get moving at all. If I put the tranny in netural the engine revs with no noise missing etc.... I also seem to experiance this hesitating again if I don't keep accelarating hard at around 40 mph. Any ideas?

 

Throttle body cleaning couldn't hurt.

When was last tuneup?

Any SES codes?

Ever replace ECTS and connector? If not, use brass style OEM replacement and replace connector (with dealer only part)

Please advise and we'll dig deeper if/when we need to

 

Last tuneup was a long time ago.

Replaced the coolent temp sencer, and had major issue with the cooling fan not working, replaced the relay, and fan motor, used a meter to run back all the wires and they all checked out. Out of need I bipassed the relay switch and ran a direct switch so I could turn on the cooling fan. BUT this problem I am having now did not start untill 2-3 weeks after all of the above.

 

PCM uses readings from ECTS to determine when to kick in fan. Since it is a 99, there is only 1 temp sensor that feeds both dash gauge and PCM.

Did you replace the ECTS connector too? Corrosion on the connector terminals is deadly and can lead to incorrect readings of the sensor resistance to the PCM which makes the PCM think the engine is colder than it should be -- hence telling it to run richer.

Where does temp read on gauge during normal operation (highway driving) ? Also, does the temp gaugebehavior seem to correlate to what you would expect? Heat up in traffic, etc...?

Let the car get up to normal operating temp, (no manual fan activation) then measure the resistance across the ECTS terminals and report here.

IF the PCM is getting bogus readings from the ECTS the air fuel mix will usually be too rich, which will cause bogging of the type you described.

 

Derf sounds like he's hot on the trail --

 

i hope you left the relay in the socket -- otherwise the fan will not automatically kick on when you engage the A/C -- which will cause the car to overheat....

by the way, 3/4 tick on temp gauge is the normalish point at which the fan kicks in...this freaks many saturn owners out but has been the case since at least 92 when I bought my first SL2.....

 

Relay is in the socket but the fan is completly manuelly operated now, it does not run thru the relay. Could that be the problem does the computer look for signial back from the fan?

No I did not replace the connecter at the time I replace the sensor.