Bean Counter

Hey Everyone,

I'm hoping someone can give me some pointers. My F150 has a very nasty habit that is nutting me up. It starts fine and, while its "happy", runs great. About every other time I've driven it, though, I will be going down the road and the engine starts dying and reviving. The "death" only lasts for a split second but it is a violent shock to the drivetrain when you're going down the road. Once the behavior starts, it seems to get progressively worse. I've been lucky that I've been able to nurse the truck home each time but I know that said luck isn't going to last. I've got to get this thing to behave!

Usually during these episodes, the the check engine light comes on and, when I check the codes, it's throwing codes 22 and 34 - which makes no sense to me since I've replace the MAP sensor and entire EGR assembly. In the past few weeks, I've repaired or replaced:

• MAP Sensor
• Air Temp Sensor
• Idle Control Valve
• Coil
• Wires
• Plugs
• Ignition Control Module
• Distributor cap, rotor, stator/reluctor
• EGR valve, sensor and controller

This doesn't feel like a fuel issue as there is no weakness or hesitation to the engine when it isn't "dead". That said, I'm at a loss for ideas - other than the PCM might be dying and is shutting down intermittently. If anyone has experienced this issue, please share how you resolved!

Thanks,
David aka Bean Counter

qdeezie

With regards to the EGR Valve and EGR Valve Position sensor, are they the same brand? When you mix different brands, you tend to get codes. I've also had some out of the box to be defective.

In addition to this, are you still using the stock vacuum lines? If so, you need to replace all of those with rubber hoses or thick walled silicone hoses before doing anything else. You'll need approximately 18' of that and two vacuum T's.

Bean Counter

Thanks, Qdeezie! I'll replace the vacuum lines and report back. Not sure if I matched brands on the EGR sensor and valve but will double check that.

lockingnut

Hi -- I have an 89 F-150 with a 3.0 engine and it does the exact same thing. Doesn't matter hot or cold, sitting still or out on the highway at 60mph. The engine's loses spark, coasts and sometimes starts back up before it comes to a rest. Recently it's happening so often I can't get it out of the parking space, which is good. But Ford but a couple other service shops haven't been able to find the problem.

I've replaced the throttle position sensor, ignition switch, ignition control module and nothing affects it. I see from your list there's other options to try but since they didn't work for you I'm hesitant to try.

Anybody else tried anything not listed here and it worked? All I can come up with is the distributor pickup assembly, and the ECU. What else could it be???

Thanks,
Don

qdeezie

Sounds like the distributor to me. Honestly, with the age of our trucks the distributor should be replaced anyway because it's such a mission critical part. If you have the know how to replace the PIP inside of the distributor, you should do so.

Bean Counter

I did a full rebuild on the distributor last weekend. All electronics and seals were replaced (man, is that gear a bugger to get lined back up).

I'm really starting to think it's the PCM. I got the truck out yesterday (kind of "darn the torpedoes, full speed ahead" experiment) to see what it would do. Sure enough, 5-10 minutes into the ride the engine started dieing/reviving/dieing/reviving. I kept driving another 10 miles or so, at which point the "check engine" light came on solid and the problem disappeared. I'm thinking that this means the PCM went into "fail safe" or "limp along" mode. With every sensor having been replaced, and with the previous intermittent on/off of the check engine light, I'm suspect that there is a fault in the PCM - not enough to kill it - but enough to make it cycle on/off. I know that I can't run the truck around in "fail safe" forever, so I'm going to replace all of the vacuum lines, reset the computer by disconnecting the battery, hooking it back up and seeing what happens. If the problem returns, then I think a new PCM is in order.

As always, though, advice is highly appreciated and I welcome any/all arguments or further suggestions!

Thanks,
David

lockingnut

Could you explain something to me? Seems like every post, thread, forum I go to uses a different set of acronyms and my head is spinning.

What is the PCM? What is a ECM? I've seen other Ford documents use "ECU" for the computer. They all the same thing? different?

Thanks,
Don

fomoco998

Do you still have oxygen sensor in use? My 95 302 was running like you described and ended up being oxygen sensor. Them or the wiring to them can cause the symptoms you are having.

lockingnut

I'll have to check. Mine's an 89. I'm not giving up on it yet. I found out there's a shop close by here with 2 older Ford Service retirees, they may be my best bet in getting this thing running. But there's still a few things I can replace myself, maybe I'll stumble onto the right one.
Thanks,
Don

lockingnut

Question - What would a faulty Ox sensor do? I mean is it capable of shutting down the engine electrically? This truck just dies, no coughing, sputtering, just quits like it's lost all spark or lost voltage to the coil. Temperature doesn't matter, it's done this out on the highway at 60 mph, and sitting in it's parking place 1 minute after starting it up in the morning. It always starts back up, happier than a puppy. Sometimes it'll go for awhile (days) other times it dies again within a minute.
Thanks,
Don