Hi guys, today I found some interesting problem, my F150 runs fine with SPOUT disconnected (Of course there is no timing advance...) BUT as soon as SPOUT shorting bar is connected the cilinder # 5 doesn't fire almost 90% of times...

I don't know what is going on, it seems to me the ECM is not comanding the 5th. cilinder to fire. I'm going to look for an osciloscop use in electronics to trace the SPOUT signal

Meanwhile, somebody had experience something similar???

 

No ideas yet???

 

im stumped, are u sure theres no broken or chaufed wires?

spout is to control base timing...hrm...without it u can set ur own, otherwise with it in place the ecu will set base timing and wont allow changes...

 

Thanks for your comments. I couldn't beleive also... until a spark analizer was connected and it shows very clear if SPOUT is DIS-connected ALL cilinders fire normal at 10º base timing, but as soon as SPOUT is connected cilinder #5 doesn't fire any more AND remaining cilinder moves to around 20º-22º

Clarification: Base timing is set by TFI-IV ignition module, it also send a DMI signal to ECU as information about what cilinder is firing and RPM. ECU use this info PLUS engine temp, Air charge temp, Intake Vacum and knoking sensor to calculate the proper ignition advance and then sends the SPOUT (Spark Out) signal back to TFI-IV module to fire cilinders at proper timing.

TFI-IV module has an impedance sensor used to know if SPOUT connector is in place or disconnected. When disconnected, TFI-IV module use its own base timing to fire cilinders. When impedance sensor detects the SPOUT connector TFI-IV module overrides base timing firing signal and THEN use the SPOUT signal to fire.

That is my problem, TFI-IV ignition module is not receiving firing order for cilinder #5, unfortunatelly I couldn't chek yet if ECM is not sending firing order signal OR it sends order but is not received or ignored by ignition module...

 

heh, good explanation. to much for me to type. good luck. no clue how to help diasnosis.

 

I am just curious, are you disconnecting and connecting the spout with engine running? I believe the engine is supposed to be warmed up with spout in. Shut off. Remove spout.
Start engine then set timing.

Probably you are following the procedures, I noticed on my 95 that if I play with the spout with the engine running timing goes berserkers.

 

Nop... I did it with hot stoped engine to connect and disconnect. I even remove battery the whole night to reset KAM memory, but same problem.

Thanks, any more ideas??

 

You already know more about your ignition components than I do, so all I can do is provide some alternative ideas. Sounds to me like you are on the right track and you probably need to replace on of the electronic components, but which one?????

This is a long shot, but something else thats free to check anyway. Is your distributor and rotor cap in perfect condition? One thing I have always had to replace many times over on my 300's, is the distributor cap and rotor. As soon as my van started running crappy, I would throw in a new cap and rotor, and bingo problem solved. I could see the end of the rotor getting corroded, after only one year. Since the Rotor cap and electronic pickup move in relation to each other as timing is advanced, its possible that a bad electrical connection between the rotor tip and distributor cap could be worsened as timing is advanced.

 

is there a way to test the igintion modules?

 

I know there are Test Stand for Duraspark modules but I don't know about TFI-IV

IceWagon, you are right this ignition system is more sensitive to Rotor and Cap wear. Mines are in good shape yet, I couldn't get and osciloscope yet so I'm going to get a know good ignition module to test, will see...

 

heh the old "known good part" test. used to do that a lot at school. found out a MAF on a ford 4.0 OHV was bad that way.

 

Well, I replace the ignition module and hte problem was75% reduced. Now it misfires just a few times every second, same as a old spark plug or cable.

Anyway I spoke to a local Ford guy and told me that ECM calculates timing based also in PIP signal comming from distributor so if this signal is erratic or faulty, all calculations for timing are wrong also, He recomend me test using a separate shielded cable to by pass the original PIP and SPOUT signals.

Let's try...

 

ur going to try to by pass which wire(s)?

 

There are 3 wires inside a shield on my truck as fallows:

1º PIP profile signal (DK - BLU)
2º SPOUT signal (YEL - LT GRN)
3º Ground for ignition (BLK)