Need help with possible coil issues

This very much sounds like a coil pack issue. The symptoms you described are exactly the symptoms I had on my work van. Bad coil packs. We replaced coils #7 & #8 on a 2001 Ford E350.

Number the coils before you pull them to make sure they go back in the same place. Use a multi meter to check continuity through the coil. You find the one that doesn't have any continuity, you found your bad coil. Only replace with OEM.

 

Only problem with this is, his coil isn't at this point of being bad. It would throw a check engine light. His is still working at idle right now, but once he starts driving under certain conditions only does it misfire. Takes the ecu longer to throw a code for that. But when my check engine light came on I did confirm it was the coil pack by doing this.

 

I tried that. All did the same thing.

 

It's frustrating to diagnose without the truck throwing a CEL but I'm not convinced that it's a bad coil pack. What spark plugs did you install? I would also look into leaky or dirty fuel injectors. Try running fuel injector cleaner through the tank.

 

I did. I used Sea Foam. I ran it thru a vacuum line and in the tank. No change. I used copper plugs gapped at 044.

 

What brand of plugs?

 

This may assist in your quest.

https://www.customtacos.com/tech.ol...06toyrm/06toypdf/06rmsrc/rm2006ta/0050029.pdf

 

.039" - .043" is the correct gap range. I tend to gap at .041". It may not make a big difference but wont cost you anything to try and re-gap.

In addition to that, I would suspect ignition coil(s) as well. Tacomas require a extremely faulty coil pack to throw a code. Its a case of chasing the goose around at this point. Personally I would change all of the coils because I've beat around the bush more than I'd like to admit by attempting to source the faulty ignition coil(s). Eventually the other coils may not be too far behinds the faulty one... or ones..

 

Op, in your opening post you stated that you had replaced the fuel pump. Tell us more about that like was it an OEM?

 

I’m pretty sure they were NGK V copper

 

It was a Delfi DFG0919.

The truck would struggle to accelerate from 2100 - 2500 rpm only. Unless I pressed the accelerator harder. Not a shutter or anything. Just like a lack of fuel.

After I replaced the fuel pump, it ran great. This was in May. The new issue started about 2 weeks ago.

 

I do not know much about who actually makes the Delphi pump. I see its not cheap. If you would have said it was some no-name China special I would have said that would be my first suspect. But who knows? I would have chosen the Denso because it only about $94 now on Rock Auto and it is likely the OE pump, unless it is possibly a counterfeit. I wonder if the low price is screaming fake or its just a good deal on a Denso???

Back to the problem. In order of costs, if this were mine I would probably first ohm spec the coils at a minimum. But next on the list would be a fuel pressure test. Toyota makes it difficult for the DIYer to do this so that will likely have to be done by someone else unless you have the parts and equip. If this is done I would hope they know better to not run dead end pressures but the factory method of in line pressures (a "T" affair is used).

 

That’s why I was scared to buy the Denso. That’s too big of a price difference for comfort.

 

Well, I replaced all the coils, and regapped the plugs to .041. Was better for a few miles, and right back to where it was. Not sure what to do now. Had a code right before I changed the coils, it was Engine Coolant Temp Circuit Low Input. I hoped it was just bad coils throwing odd codes. That code went away before I actually changed the coils though. This is frustrating to say the least.

 

Any updates/luck on this?