1990 Chevy Lumina Shuts Off when engine warms up.

[mechanicmangg]

Here is what has been done so far.

Replaced the ignition control module, all 3 coils, Plug Wires, spark plugs, CTS (Coolant Temp Sensors) BOTH, TPS Sensor, IAC Sensor, Performed Injector Cleaning, Fuel Pump, Filter, Strainer, and Replaced the ECM.

Tested the fuel pressure and it is in within spec.

Now here is the problem when the car gets up to temp and the fans kick on the engine shuts off and you cant restart the engine until it cools .

Now when you unhook the sensor and install a paper clip in the connector the car runs OK and does not shut off just uses alot of fuel.

When you hook the sensor back up the engine stalls out.

Have performed a OHMS test between the CTS connector and the ECM plug.
and I get like 4 ohms on each wire.

I am thinking that the wiring going to the CTS sensor from the ECM is shorted out against something.

Does anyone have any idea what the problem could be???

I am currently in Afghanistan talking to my wife back in the states via the Internet which has performed all the work above as she is a pretty good mechanic . This is our only vehicle and we really need some help .

Would someone please help us out.

Thanks,

Mechanicmangg

[jeffcoslacker]

Unfortunately, no...I'm not aware of a specific issue with this circuit...

Remember the CTS reading, once indicating full operating temp, allows several other things to work that were disabled during cold start...torque converter lockup, EGR, ECM starts paying attention to o2 sensor signal, etc.

You are forcing it to run in cold start, full rich mode when the clip is installed. That's why the bad fuel mileage.

I guess it stalls even in park when you pull the clip?

I'm beginning to wonder if you have a demented ECM that just won't work right in closed loop?

Any idea what the normal value should be on the ohms reading? I'm a little dull this morning, I'm not getting the significance of that reading...

[jeffcoslacker]

Whoops, see you replaced the ECM...scratch that...sorry

[biglong350]

i would be checking your o2 sensors and your catalytic converter. check the toggling of the 02's to see if their working when the computer goes into closed loop. it seems this is where your problem is. have her get an oscilloscope and check thge toggling of the 02's when in closed loop the pre cat should toggle low to 200 and high to around 800 and the back should stay steady around 4-500. of course this is in millivolts.