coolant sensor hack job / no start

  #1  
Old 04-06-2008, 11:39 AM
Thread Starter
Join Date: Mar 2008
Posts: 4
Default coolant sensor hack job / no start

I'll try to explain this the best I can, it's a bit weird...

I have a 95 cirrus that just died one day and would not start.
no codes, no anything. Took it to a mechanic who could not find anything and
was stumped. against my better judgement, I took it to a family mechanic, who did get it running.
changed the MAP and coolant sensor, plugs.
When we got the car back, the battery light was on and the coolant fans would not shut off.

This immidiately threw up a red flag to me, so I had to investigate the issue.
Come to find out, they cut one of the wires and covered it up.
So it rendererd the shiny new coolant sensor useless.

It helped the car start by making the fuel rich at start, Rough obviously, because when you hook the wire back, the car will not start again, just like before the mechanics had it.
Plus the fuel miledge is horid now.

I was a bit angry to say the least, because I got schemed, I do not believe they could have gotten it to fire, unless they hacked the wire. I can't at all with it wired correctly

So I still have no idea what is causing it not to start when you hook everything back up.

I need a few answers to check some things.
TPS - what is the process to check this on a chrysler, are all model pretty much the same ?
When I unhook the connection, nothing happens, there's a slight rpm flux but the engine
does not stumble.
how does it affect cold start?

Thanks, tim

Update on the TPS - does the cut wire render the TPS useless also ?
When I get the car started and hook the coolant sensor back up, the car will die when I unhook
the TPS connection.



 
  #2  
Old 04-06-2008, 01:03 PM
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Join Date: Apr 2008
Location: Northern California
Posts: 278
Default RE: coolant sensor hack job / no start

First: Rewire everything back to original. Use solder and insulate.
Second: Unplug, then plug back in, each and every electrical connector you can find under the hood. Proceed to inside under the dash and do the same. Then look underneath as well.
 
  #3  
Old 04-06-2008, 01:20 PM
Senior Member
Join Date: Apr 2008
Location: Northern California
Posts: 278
Default RE: coolant sensor hack job / no start

Sorry, hit a wrong button on my computer. I'll continue...

Follow that with this TPS testing procedure from Autozone.com (A good resource by the way.)
The pictures are missing, but you know where it is.

Throttle Position Sensor
Chrysler Cirrus/Stratus/Sebring/Avenger/Breeze 1995-1998 OPERATION The Throttle Position Sensor (TPS) is mounted to the side of the throttle body and connects to the throttle blade shaft. The TPS is a variable resistor that provides the PCM with an input signal (voltage). The signal represents throttle blade position. As the position of the throttle blade changes, the resistance of the TPS changes. The PCM supplies about 5 volts of DC current to the TPS. The TPS output voltage (input signal to the PCM) represents throttle blade position. For 1995 vehicles, the TPS output voltage to the PCM varies from about 0.5 volt at idle to a maximum of 3.7 volts at wide open throttle. For 1996-98 vehicles, the TPS output voltage to the PCM varies from about 0.35-1.03 volts at idle to a maximum of 3.1-4.0 volts at wide open throttle. Along with inputs from other sensors, the PCM uses the TPS input to determine current engine operating conditions. The PCM also adjusts fuel injector pulse width and ignition timing based on these inputs. TESTING See Figures 1, 2 and 3 In order to perform a complete test of the TPS and related circuits, you must use a DRB® or equivalent scan tool, and follow the manufacturer's directions. To check the Throttle Position Sensor (TPS) only, proceed with the following tests. Visually check the connector, making sure it is attached properly and that all of the terminals are straight, tight and free of corrosion. 1. The TPS can be tested using a digital ohmmeter. The center terminal of the sensor supplies the output voltage. 2. Connect the DVOM between the center terminal and sensor ground.
Fig. 1: Throttle position sensor connector terminal identification 3. With the ignition key to the ON position and the engine OFF check the output voltage at the center terminal wire of the connector. 4. Check the output voltage at idle and at Wide Open Throttle (WOT): · For 1995 vehicles at idle, the TPS output voltage should be about 0.5 volts. At WOT, the output voltage should be about 3.7 volts. The output voltage should gradually increase as the throttle plate moves slowly from idle to WOT. · For 1996-98 vehicles at idle, the TPS output voltage should be about 0.38-1.20 volts. At WOT, the output voltage should be greater than 0.6 volts. At WOT, the output voltage should be less than 4.5 volts. The output voltage should gradually increase as the throttle plate moves slowly from idle to WOT.
Fig. 2: Checking resistance of the TPS, which reads 4.51K ohms with the throttle lever closed
Fig. 3: While checking resistance of the TPS, readings should change smoothly in proportion to the opening angle of the throttle lever 5. Check the resistance of the TPS as follows: a. Unplug the TPS connector. b. Using an ohmmeter, or a DVOM set to the ohms scale, measure the resistance between terminals 1 and 3 of the connector on the TPS side. c. Resistance should measure 3.5-6.5K ohms. d. Measure the resistance between terminals 2 and 3 of the connector on the TPS side. e. Measure the resistance with the throttle closed, with the throttle about halfway open and at wide open throttle. f. The resistance should increase smoothly as the throttle plate is opened. g. If resistance measures outside these values, replace the TPS. 6. Before replacing the TPS, check for spread terminals and also inspect the PCM connections. REMOVAL & INSTALLATION See Figures 4, 5 and 6 1. Disconnect the negative battery cable. 2. Disconnect the EVAP purge hose from the throttle body. 3. Detach the electrical connector from the IAC motor and the TPS.
Fig. 4: Disconnect the TPS wiring harness 4. Remove the throttle body from the vehicle, as outlined in Fuel System of this repair guide. 5. Unfasten the mounting screws, then remove the TPS from the throttle body.
Fig. 5: Loosen the TPS screws using a Torx® head screwdriver
Fig. 6: Remove the TPS from the throttle body. Note how the throttle shaft rests against the tabs in the TPS To install: 6. The throttle shaft end of the throttle body slides into a socket in the TPS. The socket has 2 tabs inside it. The throttle shaft rests against the tabs. When indexed correctly, the TPS can rotate clockwise a few degrees to line up the mounting screw holes with the screw holes in the throttle body. The TPS has slight tension when rotated into position. If it is difficult to rotate the TPS into position, install the sensor with the throttle shaft on the other side of the tabs in the socket. 7. Install the sensor mounting screws and tighten to 17 inch lbs. (2 Nm). 8. After installing the TPS, the throttle plate should be closed. If the throttle plate is open, install the sensor on the other side of the tabs in the socket. 9. Install the throttle body, as outlined in Fuel System. 10. Attach the electrical connectors to the IAC motor and TPS. 11. Connect the EVAP purge hose to the throttle body nipple. 12. Connect the negative battery cable.
Continued:

It sounds to me like the ignition and fuel systems are receiving their power from the wrong source. Check for an ASD (Automatic ShutDown) relay. This usually supplies the power to those systems.Get a wiring schematic and start tracing and checking. Find out what systems (fuel, spark, etc.) are not functioning and then follow the schematic, checking each related system.

Be sure to get all of the electrical cleaned up and put back to how it is supposed to be.


Ultimately though, it really sounds like an EGR issue. Poor fuel economy, hard warm starts, poor idle. All signs of inert air entering the system at the wrong time. (Oh, and by the way... They seldom throw codes.)

But you won't be able to discern anything until the electrical system is back to original.
 
  #4  
Old 04-07-2008, 12:25 PM
Thread Starter
Join Date: Mar 2008
Posts: 4
Default RE: coolant sensor hack job / no start

Thanks for the detailed info, very helpful.
Thanks again, Tim
 
  #5  
Old 04-17-2008, 08:40 PM
Thread Starter
Join Date: Mar 2008
Posts: 4
Default RE: coolant sensor hack job / no start

Update- I'll post my findings for future reference here to help others. I had a bear of a time finding the right info at times.

Symptoms were as follows-

No start / rough idle
constant engine stalling. (common issue)
coolant temp guage quit working.
when it did run, the fuel mixture was horid and the exaust was
pure gasoline, which dropped the mpg to nothing.

We quit running it lean for fear of damaging the oxy sensor and or engine.

Finally installed a new ecu, and the beast took flight again.
Coolant sensor started working, fuel system is back to normal
no check engine light anymore. Runs pretty decent for now.

That could change for the worse at any time, such is life.
For now, the car is running great, and I hope it stays that way at
least till I can sell it
 
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