Misfire Coil pack tester (homemade)

[Jttoka]

Here is a simple way to detect which ignition coil pack is misfiring.

stuff needed

1. (2)spark plug wires
2. timing light

------------------------------------------------------
steps
1. remove ignition coil

2. remove rubber tube from ignion coil

3. compress spark plug wire terminal (metal part that connects to the rotor cap not the one that connects to the spark plug)

4. remove spark plug boot from the other spark plug wire that goes to the spark plug
5. put the spark plug boot on the spark plug wire that has the terminal compressed. (now you should have 1 spark plug wire that has 2 spark plug boots on it.)

6. connect the compressed terminal to the ignition coil(where the original ignition tube(boot) was).
make sure to rubber boot is covering the output of the ignition coil.

7. connect the other spark plug connector terminal to the spark plug of the cylinder that you are testing. (i made 4 wires for testing.)

*this next step you dont need to do,but i did *

8. Lock/zip tie the trigger of timing light, so you can see it while siting in the car

9. Connect timing light probe to the spark plug wire you made. Now, watch the timing light for flashes (misfire will show itself by way of a missing flash in the sequence)


In this last picture I removed the intake hoses, and mounted the MAF to the Throttle body, capped off the idle control valve, capped the other smaller hoses with tape. then adjusted the idle by way of the throttle cable.
I did this in order tonot have to deal with taking the intake off for each coil


Bad coil= no flashing
Going bad coil= erratic flashes (missing)
Good = continuious flashes (timed)

I did not find a bad coil in this test. If you have a known bad coil, please try this. I'd like to known if my idea/test works
Thanks

[3Q Jay]

nice out of the box thinking. so you detected no missing flashes by the light, but were you still exhibiting a miss/stumble?
Another thought: the threshold to get the light to trigger may be much different than the threshold to fire the plug?

[Jttoka]

Yes, stumble was still there during test. I waited for it and watched the light. no missing blink.
I even tested the coils at 200F degrees
No failure with ohm test while hot.

I got my scanner now, so i played with it a little last nite. seems my timing is at 20 degrees advance at idle 800 in gear (cold), 0 degrees at idle 625 (normal opeperating temp)

Strange thing happened test driving last nite.
I still have the ICV disconnected
The TCS SLIP light came on and the idle went up to 750-825ish in gear
Stumble went away. as soon as the light went off, back down to 625, stumble was back
I might be wrong but isnt , base idle, timing supposed to be at 650 @17.5 degrees timimg?
Ill get a screenshot of it this morning, cold and hot

[Jttoka]

Im having a, hmmmmm moment
Why is the coolant temp 89.6 degrees at stone cold start up.
air intake is only 55
I wonder if the temp sensor is bad.
ill test more today

[3Q Jay]

so I think your detector, while novel may not be a perceptive detector in this case. coolant temp--what does ECM pin 59 to pin 43 say (resistance==ignition off)?
can you get the throttle parameter to read in absolute voltage vs. percent?
short term fuel trim, if accurate, could be on to something---that is not such a good value.
timing on the scanner cannot be assumed to be absolute--only what ECU is commanding. may or may not have a 15deg offset (OBD-i nissan was famous for this).

[Jttoka]

Before I start
I'd like to say , thank you, 3Q Jay
for all the assistance, cheers

you may be right about the scanner

what a big pain in the rear getting that bracket out holding the dash bottom, smh
anyway, i have 2k between pin 59,43.
is that good or bad?
I did download the FSM, I just didnt find anything for pin 59 and 43.
also, now this might just be the scan tool, but i noticed that the tps % after a tore apart th tps and cleaned it with electric cleaner. I set the tps to 5.5%, idle at 625. timing 15 degrees, no stumble.
turned it off. waited 5 minutes jumped back in. i'll be damned, the tps showed 0% and timing was 0.
my mind is blown at this time. i have been paying attention to the timing and TPS % whenever it starts to stumble.
stumble seems to only happen if the tps % is 0, then my timing advance goes to almost 0. once it when -3.

[3Q Jay]

per page EC-121, the coolant sensor for the ECU reads 2.1k to 2.9k at a coolant temp of 20C, 680 to 1000 ohms at 50C. not linear, but exactly 2k should be ~25C coolant temp.
maybe check the scanner temp vs. an IR thermometer pointed right at the crossover pipe?
seems close enough at the room temperature end, operating temp would be the real indicator.
now, put the timing light on the marks and see what your mechanical timing setting is.
check your TPS for exactly 0.44v (key on/engine off) engine fully warmed up. then read with the scanner to see the corresponding "%".

[Jttoka]

coolant temp sending unit was 20 degrees F, high. new one installed
timing i havent gotten to yet.
I tracking down a phantom KS code. ATM
It pops up, then goes away, cold or normal temp.
ohm reading from ecu says one is out of range, at 4.5 pin 108, 2.6 pin 105.
sub connector F80 left side pin 2 .575 ohm, pin 4 .569
Where can i find the diagram for the rest of the pins on F80, im wondering where the KS ground is.
id like to do the resistor mod, to test, if the stumble goes away. I got 470K @1W

Electronic diagnois isnt my can of beer.
I would like my Good'Ole 1969 Ford F250 4x4 360cid , loved that truck, freaking work horse.
She was easy, no fuel=no run
No spark=no run
LOL
And the only brain used was the driver (i have 3 brain cells, so that counts) :):)

Cheers

[Jttoka]

Oh, forgot i also Bought a new TPS

[Jttoka]

Update

Car is up and running good. :):)

I found a problem with the O2 sensor wires. Being it kept stumble/missing in closed loop. I replaced the CTS. nope didnt fix it.
Then i remembered my Dads F250 V10, every once in awhile it would go into limp home mode and not upshift. transmission shop and dealer all said the transmission was toast. It wasnt.
A faulty wire from the O2 sensor kept blowing the TC fuse. I replaced the O2 sensor, and added an inline fuse to the wires so that if it were to happen again. only the O2 sensor is off line. It worked.
Replaced the O2...
Bingo no more codes. and she runs great.

Im sure it wasnt just the O2 sensor, Car has 135,000 miles. and needed coil packs. All the other stuff. probably didnt need replacing. But that is what happens when you get random rogue codes.

Hope this helps someone.
Cheers

New O2 sensor
New TPS
8 new coil packs
New CTS
KS resistor mod (max Advance ive seen is 43 degrees BTDC)

[3Q Jay]

sounds good. lost track of this thread. that also checks with the STFT that you saw-- I trust that has improved as well? btw which O2 did you replace? front or rear? way to keep at it.
PS- my dad/mom/step dad/me in progression put over 365k on an old 68 (galaxy)XL w/FE series 390 (same basic motor as your truck).

[Jttoka]

I replaced both pre sensors. The Pass side is the one suspect that was failing, had melted wires stuck togather.
I will be doing the rear ones also,in a week or two.