Originally Posted by cmckenna

There's three modes of failure associated with that code and they are:

1. Peak primary coil current not achieved with max dwell time (problem at the coil / component level)
2. Cylinder misfire (bad plugs and / or wires, A/F issue, valvetrain issue, vacuum leak)
3. Problem in power module to logic module interface (power / supply problem that supplies power to the PCM)


What does this mean?

MODE 1: COIL

In lamens terms, the voltage is too low and, the amount of time is not being met. That's what that means. Usually, it's a failing coil but, NOT ALWAYS as bad wires will also throw that out as well. I've had that happen with a new coil. Now, as to what else is causing this to occur:

- bad ignition wires

- bad plug

- bad coil / faulty coil / intermittent coil

- bad coil WIRE, faulty (leaky or open)

- low voltage to the coil on the PRIMARY side. Now, what's primary? The coil is a transformer (xfmr) and, at the input side, (the primary) is where the voltage comes in at one voltage (in this case, it's 12V) and is stepped up inside to 30-40 kV at the secondary respectively.

In addition to that, if the voltage at the PRIMARY side is low, the output will drop or, if there's a short in the windings on the primary side, same result, voltage drop at the secondary will result in low output. This affects the amount of voltage feeding into the spark plugs thus inducing a poor running vehicle due to the spark voltage being too low to FIRE across the gap at the plug thus not burning the fuel mixture inside the combustion chamber. This usually is followed by a misfire code as well.

Now, it could be something as simple as induction crossfire at the boot of the ignition wire. I've thrown that code many times and found it was simply a problem with El Cheapo (MSD) wires where, if the wires are poorly made, voltage leakage will make it's way into a neighboring wire thus firing off another cylinder prematurely. This is called INDUCTION CROSS-FIRE thus causing a rough running condition. It also can jump across or ARCs over to engine ground at the heads thus causing a short to chassis.

How to fix this: http://dodgeram.info/tsb/1998/18-48-98/18-48-98-v8.htm

How to check / TEST your coil:

Refer to the Haynes manual. You'll need a DMM / DVM to do this however. Simply measure across the primary side (connector side) and note whether or not the OHMs meet OEM spec.

Do the same on the secondary by measuring from the primary side (I use the HOT PIN) but, any can be used to the output terminal (secondary) and note the OHM reading. Again, should be to OEM spec.

It any of those fall out of OEM specs- R&R (remove and replace)

Next: you may have another issue. The coil may be fine. The wires may be fine, the cap and rotor may be fine but, you're still seeing that 43 code. In that case, it could be the ASD relay BUT, it also could be the FEED supply that powers it.

The thing is, with this system, or any electrical system for that matter, you've got to have a fundamental understanding of what does what on a system level.

IN this case, the battery supplies power to the PCM. The PCM energizes the ASD relay (found in the PDC box on the driver side fender) which in turn makes the connection that supplies the 12 V to the EFI system which, the COIL makes up a small part of that system as does the ignition wires, the plugs, the cap, the rotor, and, the dizzy.

On the coil INPUT / PRIMARY, there's a OR/GN wire that runs FROM the ASD relay pin TO the COIL. This supplies the 12V feed to the coil. <IF> the relay is showing HIGH resistance on the contacts, or, internally, a VOLTAGE DROP will occur. The COIL will NOT see the correct input voltage of 12V but a reduced voltage thus tripping the PCM / OBD fault code.

There's also a black wire (GROUND) that runs to the PCM connector and, once in a blue moon, people have intermittent or high resistance at the connector at the PCM connector. Remedy is to clean the connection and run an OHM test to verify it's near 1 OHM. Rare but, it has been reported.

That's only one mode! LOL. I know this sytem inside and out, forward and backward after working on it. It's very simply once you've learned it and how it functions.

Now, in the other modes, that 43 OBD code could also mean that you've simply got a misfire to which, could also be:

- wires

- plugs

- A/F ratio

- Plenum leak

I'll stop here as, you can see how this is mushroom clouding into something bigger. Really, you've got a simple issue to address. It's just a matter of troubleshooting it to find the root cause/s.

CM

Originally Posted by Sedrick_ts

my truck idles fine for about 30 seconds to a minute then starts misfiring so bad it’s almost inoperable back firing shaking and more. It rode perfectly fine until yesterday I was driving it on the highway, not hotrodding it just cruising, and it started severely misfiring almost felt like I was running outta gas. From that point on it starts misfiring about 30 seconds to a minute after started. It’s got fairly new plug wires and plugs on it and I just replaced the to coils on it. what could be causing this and why does it not start misfiring automatically.