2009 Tacoma 2.7L, Cyl 2 & 3 misfire under load

Looking for a bit of guidance for those more familiar with Taco's than I. I have an '09 Tacoma, 2WD, 2.4L with about 190k on it. Back in February when the temp was like -10F it picked up a cyl 2 & 3 misfire that is very intermittent--to the point where it will crop up in bunches for a day or so and then disappear for months on end.

It occurs almost in every case when I'm getting on the freeway and continues until it sits for a few hours on end.

What happens:

-during heavy throttle load, I seem to lose at least 2 cylinders (barely maintains or even loses speed)
-check engine light & (traction control) light blinks
-misfire continues until I pull over, and cycle the ignition (full shutdown & startup)
-this usually clears the issue for a period of time
-I can tell when it's going to have a bad day when misfire occurs on initial startup and then clears after a few seconds of running, only to return again under heavy accel. (running the AC comp seems to perpetuate things)

What I've done:

-New Coils
-New Injectors
-New Plugs

I'm not all that experienced with new vehicles (new meaning anything '73 and newer) but my next thing was trying the fuel pump/filter ASM. If somehow the filter or pickup becomes occluded by sucking up a chunk of something under heavy load, would it then make sense that when I shut down, whatever's clogging it settles back down until the next high level of demand/suction? (I usually see this in stuff that's been sitting in a field for 40 years!)

It's been a great truck otherwise.

Thanks in advance!

Pete

 

The fuel pressure would be a good next step since you have already thrown the parts cannon at the problem. Tee into the fuel supply to the rail and check the fuel pressure. NOTE: If you deadhead the gauge it will read really high as the regulator is on the end of the fuel rail and will not be in the circuit.

While idling:
Standard: (40.8 to 41.7 psi)
• If the pressure is too high, replace the fuel pressure regulator.
• If the pressure is too low, check the connection between the fuel hose and fuel pump.

Stop the engine.
Check that the fuel pressure does not change for 5 minutes.
Standard: (21 psi)If the pressure is not as specified, check the fuel pump, pressure regulator and/or injector.

 

This is good info. Thank You! So far I'm learning that with newer stuff the parts are alot more expensive ;-). I can't just swap all the tuneup items and be into it under $200 I figured with the other items I've already done, the truck was due for them anyway, so hopefully they're good for awhile.

I had to order this test set:

$31 BETOOLL Fuel Pressure Test Kit 0-100PSI with 9.497.896.30 Fuel Line Fittings

https://www.amazon.com/gp/product/B07LF26ZTJ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8
(I'm assuming it's the 7.89mm/SAE 5/16 tee) but it comes with 2 others just in case. No parts stores seemed to have the correct adapters for Toyota.

Is the idle fuel pressure supplied sufficient to provide adequate fuel under any circumstance, or will the pressure fluctuate based on demand? I ask because given the problem manifests under heavy accel, I was maybe going to try running a jumper hose/somehow placing the gauge in a manner that is visible while I drive it under those conditions or hopefully replicate the issue while observing the pressure. Or is it one of those things that if it's good at idle, it's good underway? Like if I see an extreme drop to something under that range during accel, it's safe to say the filter's clogging, the pump is failing, or there's a bad connection somewhere (potentially even with the pickup tube)?

 

That would be a good test to ensure it can and does maintain that pressure at load. Good luck on your quest!

 

Ok, I ran the test per the manual. I had to use some fuel hose & clamps because the 'correct' adapter that came with the kit still didn't work on the hose that goes into the pulsation dampener & fuel rail even though the female end of the fuel hose in the truck snapped right on to the male end of the tee adapter.

-Last night I tested the pressure idling in my driveway. It stayed at what I estimate is the high end of the range, just under 42 psi (assuming 41.7 but it's an analog guage). When I shut the truck down however, it certainly did not maintain 21 psi and dropped immediately to about 5 or so.

-I left the gauge connected this morning during my drive to work. When I fired it up, the needle seemed to bounce between 42-43ish the whole way. I made the truck act up (misfire occur under heavy accel when getting on the freeway) but the pressure maintained its level even when I pulled over and came to a complete stop and allowed the truck to idle with the misfire. I then cycled the key to clear it to be on my way. When I got to work and shut down the truck, it maintained about 30 psi (well above the 21 psi recommended in the manual)

My question now is, am I barking up the right tree? The misfire can't be cause by lean condition as there's enough fuel pressure when its occurring. Does this mean it's too rich, or is it even a fuel issue at all? I could load the parts cannon up again and change the regulator and if it's not that, the pump, but if I do somehow rule out the fuel system, what would even be next?

 

My 06 is actually in the shop right now with a similar misfire issue (not evident below highway speeds/load) - turned out to be a cylinder head problem; IIRC it was a small crack - definitely coolant leaking in. Truck's now in the shop waiting for parts. Might check coolant levels: noticed mine were diving.

 

Hmm. If that was the case, would I then see cylinder pressure pulsing into the radiator with the radiator cap off, or at the very least coolant mixed with the oil?

 

If you are maintaining ~41 psi even while it is acting up I would say it isn't the regulator or the fuel pump.

What you have is a stumper. I really have no more suggestions...

I wish you the best.

 

Maybe add in from shawniganlaker. Get the engine up to temp where it mis-fires, then run a leak down test. Maybe with the extra load / heat a crack is opening up somewhere. I would have to lookup on the 2TR-FE but if it's 2 and 4, I would almost suspect electrical. Inherent problem with I4 in general, would make more sense that the spark is getting disrupted over a crack. I'm pushing 4am now, so not really looking to go down a rabbit hole. But that could be a start.

Edit: Yeah its 1-3-4-2 so, kinda rules out a lot since 1 and 3 seem to be fine. Why 4 and 2 want to misfire, and badly at that.... Could be something with VVTI? After intake closes (or doesn't probably) causes a mis fire. Would have to hook up a techstream and check how far the numbers are off.

So finaly dead rekon guess answer, VVT-I. 2-4 are not closing all the way, plug fires, intake valves openish, blink blink bad mis fire CEL.

Edit: Sorry brain half melted, it's late. Hook up a reader and see if the VVT-I is within spec. Would be an easy test. That's my 5 min train of thought guess to diagnose something.

 

Ok I think I solved it and I'm almost embarrassed. I just got back from trying to break it. 12 consecutive on ramp accelerations so far and no issues.l, AC full blast. The real test will be throughout this week.

A friend of mine works at a shop and printed me a list of possible causes for the cyl 2&3 misfire codes I was getting. I decided to go down the list and rule out the simplest stuff first. It was a few Qt low on coolant, but I think that was because the other day I took off one of those coolant lines by the throttle body (not realizing it was a coolant line) and spilled some. I also observed it running with the radiator cap off. There were a few bubbles from it burping but not much else. If there was a head issue, I would think I would have cyclical pulsing of cyl pressure.

The list had MAF sensor & Air Filter on it. I had thought of the MAF.

I went to every parts store in the area but CRC MAF cleaner is on backorder so I just got electrical connector cleaner and a new air filter. It looks like the airbox was reinstalled kind of wonky and the back side was cracked open. I assume there was air going past the filter.

The filter itself was all grey so I swapped it out w/a NAPA gold. I pulled out the MAF sensor and sprayed it off pretty well as well as the connector.

I put everything back together and so far it's been good. Fingers crossed it stays that way. Will confirm next week.

My thought at this point is that it was either a small chunk of something bouncing around by the MAF sensor or a filthy air filter. The simplest most overlooked solution (usually) wins.

Fingers crossed it stays this way!

 

It will be great if it was as simple as that.