Hi,
Got an ongoing problem that has me stumped.
Symptoms
The overheat dummy light turns on but the car is not actually overheating.
My 2000 ford crown vic police interceptor shakes at idle as if a coil were going bad. (they're fine)
ANd When driving the red overheating dummy light turns on - the transmission feels like it slips - then car shuts off and stalls.
If it doesn't shut off it just runs rough. Then bucks and shakes. then stalls.
I monitor coolant temp with live data scanner and it never gets above 220 than drops back down as fans kick in.
The coolant temp gauge reads fine and never moves past the middle.
But the dummy light illuminates and the car stalls.
BUt I can start it right back up with no problem. However it will do the same thing within minutes.


-When does this happen?
Sometimes when I first start the car and put it into drive.
Sometimes runs fine for a couple of minutes then does it.
Sometimes after driving for a half hour.
On the freeway, roads, parking lots and at idle.
WHen cold, when hot. Always.


I have gotten speed sensor code. Emission code. cam position code

What I've done.
New idle air control sensor/valve
new intake manifold
new thermostat = came with manifold.
new cam position sensor.
a couple new emissions hoses.
new fuel filter
new ait sensor because the old one was bent for some reason.
Serviced transmission. flushed and checked for metal or bad torque converter. ALL GOOD.
new speed sensor.
flushed cooling system. running on water.
Bipassed heater core because of minor leak.

The more things I replace the worse the problem gets.(probably due to time). It started 6 months ago with a small vibration at idle. then hesitation, then buck and shake, then overheat light, then stall occasionally. Now stall all the time.

Any suggestions.
I am going to replace the water temp sensor but I don't believe that would be the problem because it fluctuates correctly when monitoring live data... and the gauge (when at middle operating temp) never moves toward hot.

Thank you for taking the time to read this long post.

 

You have a coil that is shorting out and backfeeding the PCM that is causing the lights to come on. If you can scope the coils, you will find one that is shorting out. We use the PDS or the IDS to check for coils that are shorting out. When the light comes on, the PCM goes into limp in mode. That is the transmission problem you are feeling. There is a TSB on this. If I can find it, I will post it here.

 

Thank you very much for the reply.
I will start testing the coils however I have unplugged them one at a time and eachone effects the engine. I understand that it would just be shorting and not entirely dead so that might not show anything but
The engine can run with out the use of a couple cylinders so it doesn't really make sense to me that a shorting coil would cause the car to STALL.
It sounds like you have dealt with this before and you are probably right but it doesn't make sense to me.
IS there any literature floating around the internet that would explain this in more detail?
I will get on this and test them and then post my results.
Thank you very much for your time and knowledge.

 

There is a TSB on this issue. When my &^%*$ Vista will allow me to access the site, I will find it and post it for you.

 

If you don't mind, send me the complate VIN and I will run it through OASIS. We have had about 25 of these problems and had to use Ford's diagnostic tool to determine which coil was causing the problem. With the VIN, I can isolate exactly what is for your vehicle. I understand if you do not want to send me the VIN. Just find someone that can moniter the coil performance and you will see one dropping out causing your problem. Good luck.

 

I sent you a private message with the vin.
I'll probably just buy one of those coil testers you ground on the hood and test the output. Might be cheaper and quicker just to replace them all. $200 8 coil pack at jegs.com or summitracing.com
Thank you very much for the help.

 

Answered your PM. Please post the fix back here when you get it done. I'm posting the service message here also if anyone else has the problem.

SPECIAL SERVICE MESSAGES
19183 1998-2005 MULTIPLE VEHICLES - WARNING LIGHTS FLASHING - TEMP GAUGE PEGGED HOT OR COLD - TACH OR SPEEDO BOUNCE - DRIVEABILITY CONCERN - UNEXPLAINED DTC'S
SOME 1998-2005 VEHICLES EQUIPPED WITH A GAS ENGINE THAT USES A COIL-ON-PLUG (COP) SYSTEM MAY EXHIBIT ONE OR MORE OF THE FOLLOWING CONDITIONS DUE TO RF INTERFERENCE ON THE SCP/CAN NETWORK: ABS LIGHT FLASHING, A FLASHING FAIL SAFE COOLING LIGHT, TRACTION CONTROL LIGHT FLASHING, INTERMITTENT 'BUMP'(MISS), TEMP GAUGE PEGGING HOT OR COLD, TACH OR SPEEDOMETER BOUNCE, BUCK/JERK AT CRUISE, AND/OR UNEXPLAINED CODES. THERE ALSO MAY BE AN INTERMITTENT LOSS OF RPM. PRIOR TO FOLLOWING NORMAL DIAGNOSTICS FOR THE SYMPTOM, USE TSB 05-22-08 TO DETERMINE IF THERE IS A CONCERN WITH A COP. MONITOR POWER BALANCE TO SEE IF A CYLINDER IS DROPPING OUT DURING CONCERN. IF POWER BALANCE CONFIRMS A CYLINDER DROPPING OUT AT THE TIME OF THE CONCERN, PERFORM THE COP STRESS TEST FOR THE SUSPECT CYLINDER'S COIL TO VERIFY INTERNAL COIL SECONDARY FAILURE.
EFFECTIVE DATE: 05/09/2006

 

Thanks again for the help.

Decided it would be worth the money to just get all 8 new coils since they came with the car and I assume they were original which means over 100,000 miles.

bought 8 new coils ($25 each) from summitracing.com
PROBLEM SOLVED.

Now I got to replace the busted heater core.
If anyone has pics or tips for this process I would greatly appreciate it.
Thanks

 

Go to www.autozone.com and create a free account. Then enter your information on the car and get the repair manuals for free. Just search out the heater core. It will give you complete information.

 

Mine doing the same thang coolant light flashes and start acting funny