Vinscully50

Last week, I replaced my engine temperature sender, since the only one was not working and the connector broke off. During the replacing of the unit, I dropped the new one and tons of coolant spilled out. I replaced the sender and the gauge still doesn't work. After the car cold soaked, I replaced the lost coolant (1 1/2 gallons worth) and when I started the car, it had a rough idle and acted like it was going to stall. I had to keep revving it to keep it alive. After the car warms up the idle returns to normal and the car runs fine.

However, every cold start the rough idle returns again. Could I have gotten a bad Temp Sender? I ended up buying a BWD unit from Advance. I am planning on ordering a new gauge to see if it works.

In the past I have replaced MAF, ECM, Temp Sensor, every Vacuum line, EGR and the ECM itself. The only things I haven't replaced are the IAC and the TPS. Could the IAC have gone bad at the same time as a coincidence? I did order a Delco IAC just in case.

W.E.G.

I’m gonna go out on a limb and guess you aren’t actually testing any of these parts before replacing.

if you suspect a sensor is not reporting correctly, you should test it before just blindly replacing it.

The multimeter can be your friend.

W.E.G.

Keep in mind that there are two different senders reporting to the dash gauge, and to the ECM, respectively.

That is, if you’ve got a busted sensor to the dash gauge, the ECM is blissfully unaware of the failure of the dash-gauge sender. So engine performance should not be affected by an inoperable dash-gauge sender.

Vinscully50

A buddy of mine who was a tech helped me replace most of those parts in the past. He knew the ECM was obvious, at the time my car would start but as soon as I stepped on the gas it died. He said that's the classic GM ECM failure. After the parts were replaced the symptoms went away.

I have a multimeter from harbor freight but I never know what setting to use. My buddy lives out of state now and everyone else in my town isn't into cars. Most people drive late model Accords and don't even know how to change oil. Since my friend left I've become to go to guy to ask about car problems.

Vinscully50

What is the other sensor? From this diagram it only looks like the ignition switch and the coolant sender.
https://www.thirdgen.org/forums/atta...ender-81-0.jpg

I know my ignition switch was replaced not to only after I first got this car, when my key kept sticking and I couldn't shut my car off.

W.E.G.

Should have at least four temperature sensors. Locations vary somewhat, so do some poking around to confirm.

CTS for the ECM (on the front of the intake manifold if car is V6, may be on one of the heads if V8)

CTS for the Cold start Injector (installed in the lower intake plenum - and therefore buried under the upper plenum) - pretty sure it does not talk to ECM

CTS for the temp gauge (or temp "idiot" light) - does not talke to ECM - (near oil pump I believe)

CTS for the radiator fan (This is an override-sensor, that doesn't talk to the ECM - it just kicks the fan on if things are too hot and the ECM is asleep at the switch. Located near upper coolant outlet on motor)

Fifth temp sensor is air-temp sensor if the car has a MAP sensor (measures temp of intake air) and does talk to ECM.

W.E.G.

I won't post at length on how to use a multimeter here. There are tons of resources on how to operate a multimenter on the internet. Just know that most sensor systems operate at a max of 5 volts on most third-gen stuff. The notable exception being the O2 sensor, where 0.45 volts is the "happy spot" for the O2 sensor. Not to digress too far, but, you will want to see lots of "crossovers" (i.e. running low and high, "crossing over" the 0.45 volts reading), indicating that the sensor is reporting varying conditions of rich/lean, and that the ECU is responding to continually trim the fuel to keep the air/fuel ration as near-perfect as possible, and to keep the O2 sensor voltage report as close to 0.45 volts as possible. The O2 sensor is the ONLY sensor in the car that generates its own electricity. All other sensors draw from charging-system, and operate in the zero to 5 volt range.

W.E.G.

9 minutes worth spending if you need to get acquainted with the basics of temp sensors and EFI

Vinscully50

[QUOTE=W.E.G.;6307437]Should have at least four temperature sensors. Locations vary somewhat, so do some poking around to confirm.

CTS for the ECM (on the front of the intake manifold if car is V6, may be on one of the heads if V8)

CTS for the Cold start Injector (installed in the lower intake plenum - and therefore buried under the upper plenum) - pretty sure it does not talk to ECM

CTS for the temp gauge (or temp "idiot" light) - does not talke to ECM - (near oil pump I believe)

CTS for the radiator fan (This is an override-sensor, that doesn't talk to the ECM - it just kicks the fan on if things are too hot and the ECM is asleep at the switch. Located near upper coolant outlet on motor)

Fifth temp sensor is air-temp sensor if the car has a MAP sensor (measures temp of intake air) and does talk to ECM.[/QUOT

I know I have the coolant temperature sensor in manifold near the thermostat, I probably have one near the Cold Start Injector, but the sender for the gauge is in between cylinders #1 and #3 not near the oil pump. (I believe the sender for the oil pressure gauge is near the oil pump).
I don't think I have the fan switch. I have the single fan TPI.