Misfire

[KornTruck2]

I got a 99 ranger with a misfire. I have compression on all 6, well within reason. 95-115 across all 6. Thats close enough for me. I started to trace out the cd1-3 wires, and i can get tone on one. I saw some posts that implied the connector to the coil was bad, some posts say wiring. The cd wires should go direct from the ecm to the coil? I used this diagram. If i can prove the connector isnt bad, could i just jump that wire from the ecm to the coil pack? I also see posts over ecms being fried. Am i on the right track?

 

[RonD]

Welcome to TRS

What engine, 3.0l or 4.0l?

Cold engine Compression on either V6 should be 150+ psi on each cylinder, so have the gauge checked out
Under 120psi is when misfires happen

Lets assume your gauge was just reading low, then the 20psi difference is ALOT, like 20% at 110psi average, 10% is acceptable at 150psi average

So I wouldn't skip over "its not a compression issue" just yet and retest so you don't end up chasing your tail with spark and fuel issues

1999 Ranger will have OBD2 for troubleshooting, so has several system monitors
Basic misfires derived from less power added to crank after a cylinder fires, or doesn't, from Cam sensor
Feedback from coils in the pack, a spark misfire, every time a coil fires PCM(computer) will get a voltage surge showing that coil sparked BOTH of its spark plugs
Only 3 coils in the coil pack, each coil sparks 2 cylinders, 1/5, 2/6, and 3/4 are the pairs
So have the codes read
You can get an Bluetooth OBD2 reader for $15 and APPs are free or $5
Works on ANY vehicle 1996 and newer so a good tool to have

If you can get EXACT codes, that will help you, Ford Code list here: https://www.therangerstation.com/tech/obd-ii_trouble_codes/
As you can see its very detailed and why EXACT codes are needed, lol

 

[KornTruck2]

sorry, its a 3.0
I will double check my gauge, for sure. Its an old one, i used the head to screw into my motorcycle to leak down. Always that chance.
now my code for sure is
P0351
P0353

one thing i also found out, cat was clogged up. I decided to yank that pipe down, clear out the blockage, this way i can at least get time to drive it. I have a handheld scanner, the dude i got the truck from cleared the codes. I am not scared to swap a motor, its almost easier sometimes, plus they are cheap engines. If it is heads,those are all over. I got to fix my leaks. My o2’s were trashed, head pipe was leaking. I got all that cleared out, putting the exhaust back on tomorrow. I cant do any driving till thats done.

 

[RonD]

P0351 Ignition Coil A Primary/Secondary Circuit Malfunction
P0353 Ignition Coil C Primary/Secondary Circuit Malfunction

You can "try" another coil pack

Yes, in 1999 I think the engine harness ran straight to the PCM no extra connections

You can also test the coil pack, to see if its bad, you can't test if it is "good", only if its bad, just one of those low impedence things

 

[KornTruck2]

P0351 Ignition Coil A Primary/Secondary Circuit Malfunction
P0353 Ignition Coil C Primary/Secondary Circuit Malfunction

You can "try" another coil pack

Yes, in 1999 I think the engine harness ran straight to the PCM no extra connections

You can also test the coil pack, to see if its bad, you can't test if it is "good", only if its bad, just one of those low impedence things

to test the coil to see if its bad, i used a multimeter between gnd/coil(spark) and get a reading?

 

[RonD]

Unplug 4 wire connector and spark plug wires
On the coil packs 4 wire plug in you test the 12v pin to each of the ground pins, should see 0.8 to 1.8 ohms
Look at the 4 wires, the red one indicates which pin will be the 12v pin on coil pack

Then test ohms from ground pin to that coils spark plug connections, if memory serves 15,000 is spec, but should be able to look that up
If its 0 then internal short, if no connection then broken connection inside

 

[KornTruck2]

Its for sure no compression
I did the drivers bank
4-75
5-90
6-0
I think i need heads. I found them a plenty online, may just be easier to just replace it as a whole.
its sunday, cant call boneyards today

 

[KornTruck2]

I also did a spark test, i was getting spark and i was also getting signal to the coil pack. I back probed the coil plug, all 3 had lights while running.
When you hold the gas pedal to the floor, it kills the fuel, you can hear it clear as day miss a beat, dead. I didnt bother doing the compression retest on the other bank. I used a new compression tester.

 

[RonD]

You should plan on doing both heads, same labour and just 8 more head bolts and 1 more new head gasket

 

[KornTruck2]

You should plan on doing both heads, same labour and just 8 more head bolts and 1 more new head gasket

Yea, i saw that the same way. I planned on doing both.

 

[KornTruck2]

I got the heads on the way, $225 a head, not bad. I got the fel pro top gasket set, my date code was the more expensive.. of course. Prob gonna start stripping and cleaning the oil soaked mess up.

 

[KornTruck2]

Heads showed up yesterday, got the top gasket kit. Its kinda nice, i know the exhaust studs are GOING to break and i dont have to care. I think by noon tomorrow i should be down to the block. Fingers crossed.

 

[KornTruck2]

Had it down to the block in 3 hrs

 

[KornTruck2]

Both heads had no sealing.

 

[KornTruck2]

5 hours in, i call it a day. Need to do the pushrods