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97 saturn sc2 bucking and won't rev up

my wife's car is a 1997 Saturn sc2 with 135,000 miles 2 days ago she left it on the side of the road and said it would not run. I went with her to tow it home and it started, drove for about 1/4 mile and died like someone turned off the ignition. then it was starting and stalling and would not rev up. I started towing her home and half way back she said it was running fine so I disconnected her and she drove it the rest of the way home (about 3 miles).

2 years ago an auto mechanic changed one of the 2 ignition coils and my wife said the car was doing the same thing. so I changed both ignition coils, installed new plugs gapped to .0040, check the spark plug wires for to make sure there was not one with very high resistance, and disconnected the battery for 10 mins to reset the computer. after all that, the car sometimes acts like it has a rev limiter at 4200 rpms and sometimes revs normal. and sometimes when it is warmed up it acts like it is cold and idles up to about 1600 rpms like it is going into the choke. anyone have any idea's what could be wrong with the car? or what I should check next? thanks carmine
Reply to
Jet
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You may want to stop by your local Saturn and get the codes read (and a proper diagnosis) before spending any more money on parts. The car's PCM usually knows what is wrong - you just need to ask it. It beats guessing and the fee usually ends up paying for itself.

Lane [ l a n e @ p a i r . c o m ]

Reply to
Lane

That definitly sounds like a coolant temp sensor. If its warmed up but idles like its cold(in 'warm up' mode) that means the coolant temp sensor is telling the computer the engine is cold.

There should be a rev limiter at around 4000 when the car is stopped, that is normal.

Reply to
BANDIT2941

I would suspect the alternator.

When the alternator goes, it does a couple of things:

1) It screws up the voltage that the transmission computer sees. This will cause serious drivability problems. 2) The engine computer sees that the voltage is low, and idles the car really high.

Check the alternator. If it's the alternator, I'd replace the alternator and the battery. This is because sometimes a faulty alternator will kill a battery, and a faulty battery will kill an alternator.

Also, if you haven't replaced the coolant temperature sensor yet, that would be a good idea. The original one is plastic and VERY failure prone. A bad engine temperature reading confuses the computer something awful. The sensor itself is about $15.

You might also want to replace the connector to the temperature sensor, because when the sensors go, they leak and corrode the sensor.

Good luck.

Reply to
Kirk Kohnen

If it started up again after it died, I would tend to doubt the alternator is the culprit. It definitly sounds like some symptoms are that of a coolant temp sensor. That should be the first step.

Reply to
BANDIT2941

Reply to
Dan Hicks

by reseting the computer did i wipe out the codes in the computer? thanks carmine

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Reply to
Jet

the temp gauge is working in the car does the temp gauge work off of the temp sensor? thanks carmine

Reply to
Jet

It depends.

A shorted diode can cause lots of electrical noise to be injected into the car's electrical system, confusing the computer(s). It can do this while providing enough current (time averaged) to keep the battery charged up enough.

But, it sure could be (as I noted in my original post) the coolant temperature sensor also.

Reply to
Kirk Kohnen

how can I check for a shorted diode. and how can I check the alternator. today I put a new temperature sensor in the car and it still revs high sometimes when it is warm. was I suppose to reset the computer after installing the temperature sensor? thanks carmine

Reply to
Jet

No, for some reason there are separate temp sensors for the gauge and the engine computer, so when the sensor for the computer is acting up and the car thinks the temp is too hot or too cold, you have NO FRIGGIN IDEA what it thinks.

Never go to sea with two chronometers. Take one or three.

-DanD

Reply to
Dan Duncan

From what I can tell, a 97 has only one sensor..

Reply to
Robert Hancock

Reply to
Woobie

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