'97 Taurus wagon intermittant problem

[me262]

Vehicle runs well.... Then, it will lose power. Pull off to side of road, turn off vehicle.....start it back up immediatly..and it runs perfectly. Sometimes you can go 100's of miles without a problem..sometimes 5 miles. Pull off and re-start and its okay. thought it might be fuel pump, but now I'm not so sure....

[tempfixit]

Does check engine light come on when this happens?? Have you checked for any codes? which engine?

[me262]

check engine light stays on. Have not cheked codes since I replaced a transmission speed sensor.... usually the Auto Zone code readers give a lot of worthless information. I have had experiences on other vehicles where I replaced several sensors and still not correct the problem.....

[shorod]

Originally Posted by me262

I have had experiences on other vehicles where I replaced several sensors and still not correct the problem.....

That's the reason it's often suggested on these forums to get the exact code numbers, in the form P0123, and posting them on here rather than necessarily taking the parts person's interpretation of the codes and acting on that. The diagnostic code will identify the system that picked up on a problem, but it certainly does not always indicate the particular part causing that problem. Further diagnostics are often needed which is why the professionals get to spend several months learning about new systems. If it were as simple as plugging a scan tool in and having it tell the technician what to replace, there would be no need for training other than how to connect the tool.

So, I guess my point is you should still get the diagnostic code, then post back here with the exact code number and someone should be able to offer further suggestions on where to look/measurements to take.

-Rod

[me262]

Thanks for the replies....

It is the 3.0 v-6 sohc

Went to Auto-Z and had codes read......
P0301
P0302
P0303
P0420
PO156

Any ideas????? Motor purrs along, then starts stalling(?)...losing power...give it some gas and no response...a few backfires. Stop car. Re-start and its fine for a few miles then trouble all over again....

[TaurusKing]

First three are misfire codes on bank one, the fourth, catalyst efficiency bank one, is most likely related to the first three since everything is bank one. Final code is o2 sensor, bank two, sensor two, most likely just gone bad, but check wiring harness also. Misfires could be caused by bad plugs, wires ,coils , a host of things. Might be good to replace all the plugs as a start. Maybe breaking down due to heating up after driving.

[shorod]

I agree with Taurusking, start by replacing the spark plugs and wires if they haven't been changed recently. If they have been changed recently, them make sure they are securely connected at the plug and coil ends. Another thing to keep in mind is that all the fuel injectors receive a common power and the PCM controls the ground to switch the injectors on/off. If the power connection between bank one and two is bad that could cause bank 1 to work intermittently (and cause the misfire codes) and bank 2 to work fine. If all three injectors on bank 1 lost pulse, that would also explain the stalling. I ran in to this exact scenario once on a co-worker's Contour. It left her stranded in the work parking lot. It sounded like it wanted to start, but would not. I took several tools and my handheld oscilloscope with me to figure out what was going on and when I backprobed the connector to check for injector pulse, the car started. What I found was when I backprobed the connector I applied just enough pressure to allow the connector to make contact again and the car would start and run until it got warm, then the connection would open again. Rather than replace the harness I installed a wire to bypass the connector and she never had another problem with that.

-Rod

[me262]

Plugs and wires were replaced about 20K miles ago....maybe 2 years ago. Yjey don't misfire all the time....only sporadically when something goe wrong and it loses power. Turn it off and restart and its fine for a while. Duration between power loss is more fequent now.

[shorod]

I'd suggest checking the fuel pressure. It would be great if you could check the fuel pressure when you lose power, but that could be a bit difficult. Was the fuel filter replaced when the plugs and wires were replaced? Is the engine really a SOHC or is it the OHV? If the OHV, does it have a old school distributor or distributorless ignition? I think that year was still distributor. Ignition modules were known to heat up and fail, but I would not necessarily expect a restart without a cool down period to fix that.

My money currently would be on the fuel pump....

-Rod

[me262]

Thanks!

Fuel pump is what I suspected from the beginning...except past experiences with fuel pumps were that they were either good or bad. If one failed, I was stranded. This one comes back to life with a simple re-start. Therefore, I suspect a sensor failure....but nothing except O2 sensor comes up on the code reader which could mean anything...