dwilken

engine started stuttering/hesitating once in a while. a lot now. can usually restart it, and it goes away. 1995 5.0 automatic/gas 4wd dual tank-changed fuel filter, checked pressure/both tanks and changed fuel relay. thinking ecm. any thoughts??? i don't even know where it's located and whether i can change it myself. any advice would be highly appreciated. read a ton of old posts but didn't find anything.-dave/ohio

Just call me Sean

iTrader: (1)

Check for codes, instructions at the top of this section.

dwilken

i forgot to mention that. my mechanic checked for codes, said there was only a "limp"code. which he said allowed me to get off the highway when it happened. no other codes.

94Bronc

check your plugs wires cap rotor

ymeski56

Failsafe mode? That ain't good. OBD1 or 2?
Here's what I found pokin around:
Failure Mode
Failure mode is a stand in strategy in the EEC designed to maintain vehicle operation should one or more sensor inputs fail. When a sensor input is perceived to be out-of-limits by the EEC, memorized data from the computers KAM memory will be initiated. EEC continually checks the sensors against its records of normal readings during operating conditions similar to its current state. Hold on that sounds hard! Not really, randomly EEC looks at the past to see if the engine is somewhat where it usually is. If for some unknown reason a sensor is off the charts, it can’t be trusted. So instead of tuning the engine to a possible faulty sensor reading and harming the engine and drive-ability; EEC replaces the sensor reading with a best guess from a past memory. This is why unplugging the battery to fix something works against you. Unplug the battery causes EEC to memorize all the sensor data as base line and normal. If it memorizes a bad sensor it will take it longer to call it a liar. Ford did however give EEC a very broad idea of what the sensor should be reading in its permanent ROM memory, so it will catch on to failed equipment sooner.
I am going to divide up the sensors into two groups. Ones that will cause failure mode but allow drive-ability and the sensors that will cause a no-start or barely drive. Actuators can cause failure mode to take over, but only if the failed actuator is giving a sensor reading way off the chart.
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If your obd1, I might suggest disconnecting the battery for 5 minutes to clear the KAM (Kept Addaptive Memory) If failsafe isn't allowing individual pooched sensors to show codes, maybe afterwards they'll start showing, although once again on the way to failsafe mode.

Or you could start testing sensors individually for correct input & output for proper range.

Many sensors share the same power circuits, so if that circuit was disrupted (damaged wire) you would loose all sensors sharing that circuit at once. There's a good chance you'll find some sensors w/o input voltage.

These are my thoughts on it. I've never experienced this personally. Lets see what others have to say before disconnecting the battery, but checking sensor in & out's won't hurt.

ymeski56

I'd use the method Sean mentioned & see what "you" get for codes. Failure mode is #998 during the key on engine running scan (KOER).

I think you'll find something in the key on engine off (KOEO) scan. Sounds like your mechanic didn't even run this scan. It should always be done first!!!

Just call me Sean

iTrader: (1)

Your mechanic sounds like a dumbass.

GMtraitor

Just posted on another thread, definately check for codes, I would pinpoint spark or sensor 1st ...anything recently changed on ur car that u could pinpoint???

dwilken

all good info. no i haven't changed anything on the truck. i think i'l disconnect the battery today and see what happens. don't have much to loose at this point. what ever it is, it's doing it more often. but the check engine light hasn't come on in weeks. i only drive about 20 minutes a day. when it's nice i use the cycle.

ymeski56

If it does it at idle, wiggle wires & try to duplicate it.