Looking For Help With P0351 Code

A few days ago my truck threw the p0351 code (Ignition Coil A Primary / Secondary Circut). The truck would idle fine, but would die right after shifting it into gear. I replaced the Ignition coil A and the truck drove fine for two days. I just went to move the truck today and the code came back on. Once again, the truck idles fine but dies as soon as it's shifted into gear.

Update:

Swapped the new ignition coil A to B, and put the B ignition coil on A and the truck started running fine again.

Any idea why this would be? It's my understanding that all ignition coils are the same.

 

Yeah I'm guessing that's unrelated to the p0351 as well.
You can check the igniter and associated wiring

 

I updated the first post with some new findings.

I went through the wiring and it all seems okay.

I think I'll go ahead and test the igniter tomorrow.

 

Maybe this will help?

Common Problems That Trigger the P0351 Code

• Defective Ignition Coil(s)
• Defective Spark Plug(s)
• Intake Manifold Vacuum leaks
• Carbon buildup in the Throttle Body air passages
• Defective Idle Air Control Valve or Electronic Body

https://repairpal.com/obd-ii-code-p0351

 

Update:

Last night I moved the new coil pack from A to B, and put the one that was on B onto A thinking it would throw a error for B if the coil pack was the issue. The truck drove fine today on my way to class, but on the way home died and threw the p0351 code for coil A once again. So now it seems like the issue is something else, which is really strange because the original coil pack that I replaced was in fact bad.

 

So we know that the problem stayed with A even though the coil pack moved. So what stays with the cylinders.... I'd start with spark plugs I guess, once you can test and rule out the igniter or I guess you can even look at the plugs anyway

 

Have you checked the spark plugs?

 

I just swapped the spark plugs that A fires over to B, and the plugs that B fires over to A. The truck started running fine again. I guess I just have to drive it and wait to see if it now throws a code for B. If so then I can rule it out to being the spark plugs, and if it throws another code for A then it's probably the igniter.

 

Good call on the plug swap and sounds like a good plan

 

year/make/model/motor/trans etc. please...

stab in the dark here.

try this... it appears that you are going to need someone with an scope... those wave forms are pretty specific. Let me see if there is a way I can come up with to figure this out without a scope...

if this is the correct wiring for your truck it appears that all of the IGF1 connections go through junction J12, see page 85 in the colored wiring diagram, and then locate the junction connector on page 45 of the chart.

I am thinking that there might be a loose connection and my fear is that if you start to wiggle harness's and the problem "fixes" itself it is just going to be temporary.

Any signs of rat/mouse poop in the engine compartment?

if these diagrams are incorrect let me know and i will see what I can come up with.

 

Yeah I see what you're saying. Definitely worth checking

 

I just went ahead and ordered a used but working ignitor. Found one on ebay in Oregon so it shouldn't take too long to get. Crossing my fingers that this is the issue.

 

After replacing the ignitor the truck ran good for 3 days, but threw the code again today. I noticed right before the code was thrown, the truck’s idle started changing back and forth between 600 and 700 rpms every few seconds. Not sure where to go from here.

 

Interesting, did you try putting the old igniter back in? Do you think the old one might have also gone a couple days before throwing the code? I guess I'm asking, do we think something is causing the igniter/s to fail? Perhaps the igniter is just fine and it was coincidence? We need to eliminate the igniter as a possibility, what does the FSM say on how to test it?

 

I didn't try putting the old ignitor back in, I think we can rule out the ignitor being the issue. Even though I got 3 days without codes out of this ignitor, I got 2 days without codes on the old one. I think the 3 days was just luck. Unfortunately I don't have a FSM and can't find any info on how to test a tacoma ignitor.

It's starting to seem like the issue could simply be a bad connection or loose wire in one of the connections, but I haven't been able to locate any wire that seems loose or has corrosion.

 

Took the truck to a mechanic. They had it for two days and couldn't get it to act up or throw a code. Not even 20 mins of driving around the truck started wanting to stall and misfiring like crazy. From a stop, it'll pull with normal power for a few seconds, then feel like its running of 4 cylinders for a few seconds, and then go back to normal again. Also still hunting for an idle while parked

 

Just took it for another drive and when I parked the idle started hunting, the stereo just shut off, a relay under the dash started clicking back and forth a bunch, and the HVAC noise I was already getting came back all at once.

 

I think I may have figured out the electrical issues. I went though all the grounds on the truck and cleaned them up. Also added a ground from the negative battery terminal to the body. I haven't had electrical issues since.

I'm not getting a p0351 code anymore, but the truck is having power issues around 3000 rpms. It pulls nicely to 3000, kinda gets stuck there and starts sounding like it's running a little rough, and then eventually gets around 3200 and starts pulling nicely again all the way up to rev limiter. It wasn't doing this before all the electrical issues started. Think this could due to the aftermarket ignition coil pack I put on?

 

Possible, sweet about the cleaning up the grounds taking care of those problems man, makes sense.
So do you have the MIL on now? And what code is it?

 

No MIL on now, but still running rough