85 black max 200 dva results - bad trigger?

[Fstarockr]

Here are some numbers I got today: sn is 628*** 200 black max, 85 iirc-

Intermittent spark across most cyls, but cyl 4 is awful, on and off, fluttering about-

I double checked the kill switch (yellow/black wires removed made no difference)
I also disconnected the reg/rect (no difference).
Carbs just rebuilt, max timing set at 20 degrees cranking, idles around 6 degrees ATDC-

Huge puffs of smoke on startup and a really nasty eye burning smell (unburned fuel). I mixed a fresh mix of 50:1 for testing. Battery fully charged and all connections in good shape.

Here are the results:

DVA: (motor idling)

2-4-6 (outer switch box/YELLOW sleeve):
purple to gnd: 4.3v
white to gnd: 15v ***
brown to gnd: 4.3v
Blue (low speed) to gnd: 314v
Red to gnd (high speed): 198v

1-3-5 (inner switch box/ BLACK sleeve):
purple to gnd: 5v
white to gnd: 4v
brown to gnd: 6v
Blue (low speed) to gnd: 266v
Red to gnd (high speed): 203v

Stator (2 yellow wires): 92v (at idle)

Bias circuits (wire disconnected and measured terminal to ground):
Both: 960 ohms (ill have to recheck 2moro to make sure the k or M wasnt appearing, it was dark with a headlight), "should" be 9000 or 15000 depending on make ive read.. so IF this is outside those specs could the switch boxed also be bad?

[Merc 2.5]

I'd start with switch box myself , I've replaced so many boxes on motors. many many. but never seen a trigger go bad. just my experiences. swap em around and c if it follows the box

I dont have a manual in front of me to look at ur values either. of course it is possible trigger bad. Also trigger needs b tested in multiple positions. not just idle position

[Fstarockr]

Hi understood thanks - i did some more tests yesterday and the trigger seems fine actually- i wasnt familiar with the v6 / double switch box triggers and was testing them wrong - they were all in spec.

I loosened the coil screws and the misfire was gone! taking it down to the water this morning - the issue is at idle anyway, intermittent spark, moving about- i suspected coils and grounding so will check and report back-

[Merc 2.5]

I have had few boxes fire at idle gud then go back to chit , also had em miss at idle and fire all 6 above 1500 2k rpm. boxes can do crazy things

[Fstarockr]

hi yeah back at the motor, #1 has intermittent miss, moved wires at pack and issue still at #1 like its following the brown wire (trigger).. would bad packs give these symptoms?

dva on trigger terminals while running where its missing seem ok, but the brown wire is 3.5, .5 v under spec..

dva between trigger wires on packs are 12v, 10v and 12v, cdi spec says 4v+, coil wires are 210v at packs and very close at coil +.. all have strong blue open gap arcing..

swapping the wires at the pack and still same issue on #1 indicates trigger, its staying on the brown wire from the trigger basically.

cdi says i can check dva disconnected to verify trigger vs pack, i presume thats during ceanking/not running simce thw wires are disconnected..

[Fstarockr]

**Update:
So bumping the idle to 1800 is now throwing intermittent spark across at least 4 cylinders maybe 5. im not sure what cdi means here:



How do i check the "disconnected" side? im getting OL with probes between the 2 wires.. connected/running im getting around 5v between each trigger wire/terminal


WIRE READ TO RESISTANCE DVA (Connected) DVA (Disconnected)
Brown (Black Sleeve) White (Yellow Sleeve) 800-1400 4 V + DVA (Connected) 4 V + (#)DVA (Disconnected)



(#) This reading can be used to determine if a pack has a problem in the triggering circuit. For instance, if you have no
spark on one or two cylinders and the trigger’s DVA reading for that cylinder is low – disconnect the trigger wires and
recheck the DVA output. If the reading stays low – the trigger is bad. If the reading is now within spec – the pack is bad.
(Service Note) You should get a high or open resistance reading to engine ground from each wire, but you will get a DVA
reading of approximately 1-2 Volts. This reading can be used to determine if a pack has a problem in the triggering circuit.
For example, if you have no spark on one cylinder and the DVA trigger reading for that cylinder is low – disconnect the
trigger wire and recheck the DVA output to ground from the trigger wire. If the reading stays low – the trigger is bad.

[Merc 2.5]

hi yeah back at the motor, #1 has intermittent miss, moved wires at pack and issue still at #1 like its following the brown wire (trigger).. would bad packs give these symptoms?

dva on trigger terminals while running where its missing seem ok, but the brown wire is 3.5, .5 v under spec..

dva between trigger wires on packs are 12v, 10v and 12v, cdi spec says 4v+, coil wires are 210v at packs and very close at coil +.. all have strong blue open gap arcing..

swapping the wires at the pack and still same issue on #1 indicates trigger, its staying on the brown wire from the trigger basically.

cdi says i can check dva disconnected to verify trigger vs pack, i presume thats during ceanking/not running simce thw wires are disconnected..

Cdi has different values than oe merc stuff , so if ur trigger isnt a cdi then u need find correct values. I have a manual for that motor at home. I'll give u a call later on. U can prob move wires around like ur doin. but I'd rather just swap boxes around and see if it goes to #2

[Fstarockr]

ok some numbers - this while motor is running:




Bias results are 14000 and 18000 - is that bad?

at idle intermittent spark seems to be on 1 - but 400rpms more and 4 cylinders are all over the place..

[Fstarockr]

cdi does list 2 different numbers for oem/cdi - i have replaced the packs, stator, trigger and STILL intermittent spark.. it drops for like a split second at idle / fast idle - only DVA reading that stands out are the red wires, theyare pumping out 200v at idle and spec says 20v+ ..

[Motv18]

Edit other thread doh

[eli]

if you got spark and it wont run please do a leak down as stated before you might be suprised on the condition of rings ,cylinders

[Capt.Insane-o]

Stator orientation?

[Motv18]

Think I just spotted it red spec in some books is 20-90v at idle your getting low side v through the high at idle.

Low should drop as rpm increases and high should take over between 2000-2500

someone doubble check that

iirc that will kill the trigger signal through the bias? Lot of loops in the box to wire the relays the 4 v from the trigger cant overcome the higher voltage to the back side of the relay and fire. And if the reds are gaining 300+ at 1200 it starts killing anything getting stronger trigger volts.

mights dva the yellows as well. It could be off as well.