The car is a 96 Taurus dohc v6. The problem I am having is intermittent. The first time it happened was about 5 years ago. After adding gas taken from a 67 GTO I was taking apart. I drove the car for about a day with that gas and while I was on the parkway the problem started. The car felt like it was losing power and then it stalled. Almost like vapor lock. I tried starting it and it ran rough. I sat and waited about ten minutes and it started right up and ran fine. I added some injector cleaned. I figured the gas I put in may have been dirty or maybe bad. And I didn't have any problems like that for about 4 years. Then it happened again while I was on the parkway, same problem. Limped home, added some gas to the car and injector cleaner and then the car ran fine for about 8 months. It happened again last night I put gas in before I got onto the parkway. Drove home and everything was fine, then it acted up just before I got home. It stalled out and I limped home. I put some gas into it and some injector cleaner, but this time seemed worse. It wouldn't start, and when it did it ran for a second and stalled. I pulled the plugs and they were dark tan. I gave everything a visual check and it seemed fine. I went inside and ate dinner. After an hour I came out and it started right up and drove fine. This morning I used it and it was great for awhile then it acted up again.
The previous times it had acted up I didn't get any codes, now I got P0171 and 0174. I also noticed that the pvc hose looked flat, I don't know if that would have anything to do with it. I was thinking maybe the sock or the filter in the tank may be getting clogged and when I shut it off the garbage falls off.
I have worked on cars for 40 years and worked in dealers for 15 and never had a problem like this.

Any ideas.

 

I just took it for a ride after it has sat for about 1 hour and it ran great.

It's hard to fix a problem like this.

 

the codes mean both O2 sensors on exhaust are registering lean, I would also suspect a fuel issue first of all from your explanation...perhaps fuel filter is clogged? stopping would allow a filter to clear up in a lot of cases....perhaps the tank has chunks in it clogging the intake....

if not fuel....I would suspect an intake leak or maybe a MAF sensor (but it isnt throwing MAF code is it?)

for an intake leak....usually intake gasket leaks happen when its cold and swell up when warm and leaks go away....do a carb cleaner test....spray around intake when running and see if engine stumbles(because vacuum will suck in spray)

check hoses....

my 2 cents....hope you get some new ideas

 

your pcv hose should be replaced...hoses can get mushy when they get hot...check hoses for this possibility....

try and test fuel pressure when it is acting up...perhaps fuel pump gets hot and cuts out?

pull out fuel filter and shake it out and see if junk comes out.....that would be my first check.....


im just saying......

 

last thought....

perhaps its a coil? coil getting hot and cutting out also fits your description....when they cool off they start working again.....

was it missing? or bogging? (bogging would point back to fuel/intake stuff)

 

Thanks for responding. I might lean towards the fuel filter and or the sock in the tank on the pickup (if there is one). The only thing that screws up all diagnosis is that it happens once every 4 months or in the the first time 5 years.

No MAF code, I thought that too.


As for the intake, the car dosen't cool down all that much between the problem and it clearing up.

Checked the hoses and they all seemed fine except for the PVC line.

 

Hard to check fuel pressure when it happens, you don't know when it will happen. Maybe tomorrow, maybe 4 years from now.

 

Took the car out today, no problems. The problems seem to happen when I drive the car for long periods. 40 minutes or more. And it always seems to happen after I have added fuel.

 

if it happens after you fill up...it makes sense that the act of putting gas into the tank is stirring up junk in the tank...which gets sucked into intake....

once car sits for a while....stuff settles and wont get sucked up again until low fuel refill stirs it again...

definitly look into fuel system....replace filter/fuel tank debris and the like

 

It has been over a week now and all is fine. I haven't replaced anything or clean the tank out. I am going to wait until I have some extended time off. I also haven't taken the car on the highway for any trip longer than 20 miles. But all is well as of now.