I'm still having a rough run on my '87 F 150 - 6cyl, EFI, 4X4, 4spd.
The mech who just "worked" on it (worked it over) sez it's definitely the "Brain" (PCM).... But he also said some other things that I think aren't correct, so I'm asking you folks.... How often do these things go brain dead? Can a fuel problem (like a clogged filter) create a similar situation, where can I find a replacement PCM since Ford doesn't stock them? I've run a few scans on the truck and come up with odd readings from system pass to a few specifics, have changed the oxy sensor for bad wires and the temp sensor for a scan code ... the temp sensor made a difference briefly - a few miles - or that may have been coincidental.... Also noticed now that I have it back from the shop that the rear cat has ruptured along the seam..... Probably a backfire.... So do I assume it may be plugged up enough to change? Could a backfire like that hurt anything else I should be looking for? The Engine and trans have about 50,000 orig. miles but everything else has more miles due to a "total" rebuild..... So the fuel system, exh, etc have all seen more use- no idea on how much more - enough to have a rotted out muffler and old bushings, etc.... Any ideas would sure not hurt.... Thanks!

 

Did your mechanic give you an explanation as to why he thinks the Ecu is the problem ? What exactly is the problem you are having ?

 

The mech said that when he bypassed the computer it runs ok.... This is not necessarily true. The truck has always run fine since I've owned it. a couple months ago it started to miss slightly while driving. this got progressively worse and I replaced the plugs and sensors mentioned earlier. It would run after starting for a couple minutes (closed loop I guessed) but then after a few sessions like that would run rough as soon as it was started. That's where things are now. As I said, I've scanned it a few times but really haven't got anything conclusive I don't think. So tomorrow for fun I'm replacing the fuel filter - can't hurt. also, the mech said they tested fuel pressure all the way thru and it was ok, and an exhaust pressure check was ok,..... I really can't say why the mech feels it's the PCM and of course, he won't disclose much to me because after it sitting in his shop for 3 weeks with no results, I brought it home, not as broke as he hoped, I'm sure, but what little he did still cost me three bills (ransom I guess).... I've lost all faith in shops so I'm really on my own here - a wrench for years but not on this new stuff.... My others are an '81, a '62, and a '57...... Thanks...

 

I had an '85 Lincoln Mark VII that just quit while I was driving, no stumble, no backfire, it just quit. I know that it's not a truck but I found out the computer brain ceased to exist any longer. Newer Ford models(truck and car) had their computers incorporate a "limp home" mode, in which if there was a circuit failure inside the PCM you could still drive the vehicle and not be stranded. I know it is hard to diagnose PCM problems without the proper tools, and sometimes people are quick to point that the computer is the culprit. If you feel all other avenues of repair have been traveled, I'd try a(or a few) salvage yard(s) that deal in late model vehicles to see if they have a PCM for your vehicle, it'll save you a few bucks. If you don't feel confident about used PCM's your local parts house may be able to get one, reconditioned of course, for alot less money than a factory or dealership new model.
I hope this helps in any way.

Todd
BB79RANCH

 

Try http://www.copartfinder.com
save a LOT of driving around, up where I am (93012, southern california) the closest yard that has a F150 is 27 miles away, and they have ONE, next yard is 48 miles away, and they have TWO! LOL!

1995 F-150 XL Reg Cab/Bed
http://members.sounddomain.com/blind
5-star rated F-150 (big stereo)

 

I hear that - I'm in sagebrush country myself -few and far between is not just a phrase here- it's LIFE. Thanks for the help - someone posted a ford parts site a while ago but now that I need it I can't seem to see it... Anybody know where?

 

Its rare that an Ecu will just die . If the fuel pressures are correct & consistant , then focus on the ignition system . Check for any stored trouble codes after the vehicle is at normal operating temperature . Make sure all engine electrical connections are secure . Dont paint all mechanics with the same brush , some know how to diagnose Efi systems & some just stumble thru avoiding or not knowing the proper diagnostic routines .

 

I know the mech said your fuel pressure was fine, but lemme tell you, Mine checked out fine too. See the post a page or two back "bad way top start the new year.." and you'll see what problems I was having (super rich, stumble while driving). After having a mechanic check the fuel pressure and saying it was fine, I still replaced the fuel pressure regulator. Ran like a champ after that. BTW: thanks to all who hepled me out...

Hope my rambling helped...

 

Hi, give fordpartsonline.com a try see if they have it and how much it is I haven't run across anything they couldn't get and send to me cheaper than a local dealer and he is in California it is Atascadero ford I'm sure he can help with a computer.
John