Intermittent loss of power or stalling

[charliecoker]

So i've been chasing an eletrical problem for a couple months, and i've about lost it.

to preface, I have an 89 Ranger, 2.3 manual DIS. Somewhere around 260,000 miles, original engine and transmission.

Starting around three months ago, my tach quit working. Not a big deal, i've driven the truck for 10 years, so could feel it out just fine. a week or so in, it starting having trouble starting, like it wasn't getting gas or spark. After a few turns it would always start, and run without any hiccups or stalls. Pulled the codes (i cant remember the numbers now) and it told me something about SPOUT circuit fault or grounded. Read a little, decided to check out my ignition module. Had it tested, it failed for the SPOUT test. Replaced it, drilled and tapped a new bolt for the fourth hole (that wasnt used on my factory ignition module) that the paperwork claimed i needed for a ground.

No change.

I began testing wires between the ignition module, coil packs, and ECM. Everything checked out okay. Pulled every ground I could fine, cleaned them, and replaced with dielectric grease. Tested my coil packs to the resistance spec from my Haynes manual. Tested a little high, figured (well, they ARE almost 30 years old) and bought new Motorcraft coil packs.

It ran for 25 minutes straight before turning off on me. Then acted just like it did before I did anything.

Read some more, pulled codes again. Came up with a loss of tach/IDM failure. Once i figured out what the IDM circuit was, I checked continuity on the wires that a diagram told me to check, everything was good. Came to the conclusion that the crankshaft position sensor had probably kicked the bucket, maybe an intermittent failure. After installing a new one, it seemed to be the ticket.

The only issue i had was a random sputtering when driving below 2500 rpms. Ive had issues with my EGR valve for years. Replaced the entire system years ago, still had problems. Pulled the electrical plug on the vacuum solenoid, and havent had problems for years.
The truck sputters whether its plugged in or not.

Last week, im driving to work, and the sputtering happens. Check Engine light comes on, so I pull codes again. Nothing shows but the EGR issue (which again, has been there for years and never once caused an issue.)

So last Friday, im driving home from work. Inching along at a busy stop light, it gets to chugging and acting crazy like it lost timing or something. Luckily had enough momentum to coast the side road. Pulled codes and the IDM failure/Loss of tach is back. Let the truck sit long enough to have a smoke, decided to give it a go before calling a tow truck.

It fired right up and drove home without any issues.

At this point im rather confused. I could keep swapping parts and dropping a ton on expensive electrical parts, or i could ask for help. I'm all ears on any advice or insight into this. At this point, the only thing I think it could be is the ECM, but I dont wan't to jump to conclusions anymore if I don't have to.

I'm sorry if this is confusing at all. Sitting here, enjoying a beer and trying to recall all the mess i've dealt with for the past couple of months (this is not the only high mileage old vehicle i try to keep running. Cheaper than a payment they say...) Thanks for any input.

 

[tomw]

I'd check the module once again. The description makes me think a 'heat sensitive' problem, where components are not liking the heat, and either move apart, cutting conductivity, or are just temperature sensitive, such as a semi-conductor that works fine cool, but fails hot.
tom

 

[charliecoker]

I had considered this, but didnt want to believe that my brand new 120 dollar ignition module was crap out of the box.

I will try relocating it maybe this weekend and report back. Thanks for the input!

 

[tomw]

I searched for an image, not owning one, and it appears similar to the TFI module used previously. ebay has them for $99.
Can you heat yours and test it before deciding to replace it? There should be a test procedure to determine if it is failing. Did you use the 'white' heat sink compound when you mounted yours? The old ones mounted to the distributor(single plug/single coil) required the heat sink compound, and were subject to a class action suit because of design flaw leading to early failure. I think I did 3 or 4 back when.
In those cases the engine would not start.
Have you checked for spark when you are having the problem? If the coil or crank sensor(if equipped, I don't have the ignition-year changes memorized) fails, you may not get spark.
tom

 

[RonD]

I would open up the computer and have a look at the circuit board

Good one seen here: http://www.auto-diagnostics.info/ford_eec_iv

Any areas with discoloration would mean replace the computer.

The ICM(spark module on intake) does run the spark BUT...........computer can over ride it to advance and retard spark timing based on Driver input, mostly from TPS(throttle position sensor), you can test TPS with Volt meter.

The ICM sends the computer the PIP(ignition pulse) signal it gets from the Crank position sensor, it uses this for fuel injector timing and also calculates "best" spark timing from this signal
The computer sends the ICM advance/retard "instructions" via the SPOUT(spark out) wire.
If you were to disable the SPOUT signal, which was needed to do base spark timing, then ICM would run the spark based solely on RPM(from crank sensor), this would make engine sluggish, slow to react to driver input.
The SPOUT is in essence the Vacuum Advance used on older distributors, opening throttle plate dropped vacuum in intake which changed spark timing in distributor.

So test the TPS and its wiring, and take a look at inside of computer