Alittle over a year ago i posted about a pulsing/surging from the engine that would occur when the rpms reached 3200. once this happened, the temp gauge would usually start to fall fairly quickly. well, i got around to installing new plugs and wires the other day. have not had a chance to get it a full test by going on the highway (about 70mph) but from what ive seen while keeping the rpms around the 3-3500 range as much as possible, the pulsing/surging sensation seems to be gone!! *crosses fingers and knocks on wood.
....BUT. now my temp gauge is more random than ever!! for example. the other day i ran to the hardward store about 5 minutes from my house. on the way back, sitting at a light, my temp guage starts to drop and now it drops almost instantly rather than gradually like before. my car also slightly sounded like it was going to stall (i feathered the gas when this happened). then just last night, while sitting in the drive through, the temp gauge was acting up again. i let it kinda go on a bit this time and it never stalled, but i could see the cluster lights dim JUST a bit when the temp dropped. the best i can describe it is the car would run just fine, then the temp drops and the rpms will lower as if something just kicked on/or off causing it to slow down the rpms. then after a couple seconds the rpms would return back to where they were.....
any idea what could produce such symptoms?? thanks guys/gals!
Sounds like this is a possibilty.
Your temp gauge works off of a coolant temp sensor, a coolant temp sensor, that has a ground, a five volt reference, and a signal to the PCM.
.For example 5.0 volts is fully cold, -40F and 0 volts is overheating like 250+
Now as temp goes up, more voltage goes to the computer this is done using a thermister, which changes resistance with temperature.
With your gauge acting the way it does, it almost seems as if the engine is going fully cold, which could be caused a faulty ECT sensor, or a problem with the connector, as it seems like it loses input for a brief second every now and then.
Your driveability problem could be, because at fully cold -40F, which is the default for the ECT if the connector say is unplugged, it will richen the mixture up quite a but, as we know colder engines run a bit richer, because the fuel tends to condense on cold metal.
So your vehicle would be getting to much fuel
In short, I'd go outside, look at the ECT sensor connector, make sure its good and snug, unclip it, make sure the prongs arent bent or anything, do you have a multimeter if so you can test it, let me know if you need directions on that
- 2004 Cavalier - 124k, owned since new
no multimeter... where is the ECT sensor?
thanks a bunch for the post and help!
Depends on what engine you have, you are looking for a connctor conncted to a sensor, that is in a coolant passge, nine times out of ten, its close to thermostat
- 2004 Cavalier - 124k, owned since new
The temp sensor is on the steel pipe that comes out of the side of the head and runs across the head. Its closest to the pulleys end.
I had that happen a few years back. I had unplugged the sensor to just check the sensor to make sure it was ok (i was going thru the whole car before a cross country trip) and the wires that go into the plug broke. I could not tell though. I replaced the sensor and that didnt help so i picked up a new plug and replaced it and the problem went away. The problem you are having sounds like the problem i was having.
anyone have a pic of this plug/sensor??
Dont have one but the sensor should be on the black radiator pipe that runs on the right hand side of the car. Should be the only sensor in a coolant pipe. If i do remember correctly the plus should be the same as the intake air temp sensor so if your parts store doesnt have the one for the coolant sensor the one for the intake temp should work as well. Its been a good 6 years since i had this happen so i might be fuzzy on a detail or two.
