Can't locate cause of misfire and all codes come up as permanent!

Hi there, own a 2011 tacoma 4.0l with 321k kms on it. Been having issues since December 15th. Fueled up the night of the 13th from a different station than I normally do, only mentioning this because it was thought to be bad gas at first.

December 15th :
On the way home CEL came on and flashing, truck started shaking and running rough. Pulled over and hooked my code reader up and threw a p0301, cylinder 1 misfire. Limped it to work, down the road and parked it.

Drove work truck for the week and the picked it up on the weekend to go take a look at things.

December 21st :
CEL did not appear right away after clearing and seemed to run normal again. It warmed up for a good 20 mins and no misfire present, running normal. Drove about 2kms down the road and CEL and symptoms came back.

Halfway to shop scanned again and it says P0304 now! Misfire changed cylinders.. (NO P0301 CODE SINCE)

Limped it to the shop to change spark plugs and investigate further. Changed all 6 spark plugs with NGK plugs. Issue not resolved.

Flipped coil packs around and no noticeable difference but replaced the coil packs on the cylinders that had misfires hoping for a difference and notta. Called it a day. Left vehicle at shop

December 22nd:
Went back out to check over what I had done the previous to make sure I hadn't left anything loose. A friend helped pull the air intake off to change #4 injector because I've never delt with injectors all that much.
(Ended up replacing #3 due to following wrong advice. Thought cylinder 2 4 6 was on wrong side..) ONLY FOUND OUT THE NEXT DAY

When it was being put back together engine was turned over and forgot to plug in maf sensor and threw couple airflow codes. Plugged everything back in but codes will not go away. New codes - P0102, P0113

After that all the codes that popped up stayed present no matter what code reader was hooked up. All codes are permanent and will not go away not matter what!!

Also ran some injector cleaner through a tank of fuel because it was previously thought it was bad fuel.

Dec 24TH :
Went in and changed injector #4, cleared codes. Made sure everything went together good when clipping all the connections back together. Made sure all hoses went back tight.

NOTES :

Codes continue to come up as permanent and wont erase from truck.

Misfire is not present on first start up of the day. But after it goes off I can turn it off and misfire will dissappear until driven again or it has a little misfire on idle. 50/50.

I'm stumped and not 100% knowledgeable of all this stuff. Did lots of suspension but trying to learn this stuff now that i kind of need to.

I've been doing a lot of research and came across a lot of answer which a lot seem to be coils, plug or injectors which I've attempted. Also came across ecm issues and wiring issues and a few others that I have not rulled out yet. Hoping the engine isn't toast.

I've come up with a list of things to dk next time I'm at the truck, just difficult where it's pretty cold out now, I live in nova Scotia. Here's the list :

Check maf sensor - replace or clean
Tps sensor clean or replace

Check wiring/connectors and grounds

Ecu -
unplug fuse under hood for ecu to flash it
Unplug ecu if fuse doesn't work

Change spark plug from cylinder #4? Or atleast check

Run fuel through truck more with more fuel system cleaner




If anybody has any advice I will take any I can get. If anybody has dealt with anything similar please chime in. I'll read any stories of anybody having issues and solving them if it gets me another step in the right direction. I'll take any input I can get.

Thank you very much in advance!

 

I’ll guess spark plug tube gaskets. Good luck!

 

Here is what I read about PDTCs - permanent diagnostic trouble codes:

“PDTCs are designed to remain in a vehicle's electronic memory until the associated problem is repaired. Instead of being cleared by a scanner or diagnostic device, they rely on the OBD system to confirm that the emissions problem that triggered the code is no longer present.

This process plays out over something called a "confirmed fault-free monitoring cycle." Once a repair is complete, the car or truck must drive at speeds of 25 mph or more for at least five minutes, idle for more than 30 seconds, and have its engine operational for a full 10 minutes. This needs to happen three times in a row without re-triggering the code before the computer accepts that the problem is resolved. The PDTC is then deleted from memory.”
https://www.capitalone.com/cars/lea...pdtc-what-is-a-permanent-diagnostic-code/2413

 

I've tried to run it each time after doing each repair and the permanent codes are still present instantly after trying to do the drive cycles. Cel flashes before I can run it long enough. Would the other codes like maf sensor and stuff go away after running it even if misfire comes back or would that stop all codes from erasing? I've had that thought that the misfire may be stopping it from erasing but wouldn't it just be the misfire code that would stay?

 

Needs new vacuum tubing?

 

You need to be looking at live misfires not codes.

As for codes there's 4 basic types of codes:

Pending: Codes that have been detected at least once in the past few drive cycles but have not failed enough times to turn the check engine light on or be flagged as a current code.

Current/Active: Fault has occurred in the current drive cycle.

Stored/History: Fault has been detected in the past but is not currently present

Permanent (Beginning around the 2010 MY): Similar to Stored/History codes (note that codes flagged as permanent can not be cleared with any scan tool or by disconnecting the battery even after the problem is fixed, the ECM/PCM will delete them once the monitor(s) for the specific code(s) run and pass 2 or more times in a row).


https://www.tacomaworld.com/threads/scan-tool-discussion-recommendations.834898/

 

Hi there, thanks for the few suggestions. I got out there yesterday and started from square 1, flipped coil 1 and 4 to see if any change was noticeable. Nothing. Went for a drive and still the same misfire.

I pulled spark plug 4 out(misfiring cylinder) and swapped it with one we had in the shop(not brand new). Pulled each coil pack out 1 at a time and made sure connections were clean, which they were. Also made sure rest of plugged were in there good.

Moved onto electrical connections/harness and double checked my injectors.
All connections clipped together good and were clean. Went up and down harness looking for rough wires and couldn't find anything that looked to be pinched, nibbled on or damaged in any way.
As I went over injectors I noticed the seal around injector #3 look like it had a drop of liquid on it. Pulled it, wiped it the wet spots and popped it back it tightly.

As it was going back together I noticed some very light corrosion around where the intake manifold bolts down. I cleaned up where the gasket seals, popped it back together carefully and made sure all tubing was tight. Cleaned the throttle body also because there was some gunk built up on one side. Cleaned up the seal on the throttle body as well.

Turned it on, threw only throttle body code and p0304. Reset them and they were only there as permanent codes which would have been stored. Misfire wasn't present. Went for a good drive about a half hour or more going various speeds and what not. Trying to complete drive cycles. Seemed to be better.

When I get back to the shop I turned it off. Then back on when ready to leave and it currently has 0 codes present. Misfire and throttle body code are gone.

Took it home last night once all was packed up and it's drove a lot better. Just notice it's a bit sluggish on acceleration. No spit and sputter anymore though so I am happy about that.

Going to get another plug this morning for #4 where I put in a used one.

Any body have an idea of what might very been my issue. I'm not 100% on what my problem was where I did a few things before it going together again. I was thinking spark plug but if anybody has input I'll take it.

Also any advice for the sluggish acceleration now? Or would a new plug fix that?


Thanks for the help, much appreciated.

 

Spark plugs. Probable fuel supply issue due to a fuel filter being filled with debris.