Tacoma running rough no CEL

Keep us posted; seems there’s a small group of us that are all invested in helping you getting this solved as systematically and inexpensively as possible.

 

I still say look for the mechanical issue. If it were dirt in the fuel, wouldn't ALL the cylinders be misfiring?

 

Update
Break in the rain allowed me to do some more investigating
Cranked it in the driveway and let it run long enough to reach operating temp
Checked oil, no water in it
Pulled plug out of #2 after it ran for 5 min and it was dry, nothing on finger across it or paper towel.
Connected compression checker and cranked a few seconds and got around 208 psi
I listened to injectors with mechanics stethoscope and all sounded pretty much the same to me.

I think the injector is clogged or broke

Bad news is fedex is holding my set of injectors hostage in Compton for who knows how long
Sucks to pay for 2 day shipping and then find out the next day that the shipper cannot deliver and KNEW they could not before accepting 2 day shipment

Andy I will not leave y'all wondering, promise to keep updating as I go

And once again thanks to all who have contributed

 

Well. it looks like the mechanical is OK. I hope the injectors will fix it. However, I think it may be something else.

 

I have a similar problem w/ my 2.7, sometimes it runs amazing and sometimes it misses. I have literally replaced everything (including the head) yet it continues. I don’t get a fault, never had a missfire fault but it certainly feels like it. For some bizarre reason it ALWAYS runs great when it’s humid or rainy?!?!? Today it ran awesome, tomorrow it may struggle but there is an obvious and apparent difference between the two. I imagine somewhere, for something, I have a cruddy connection or chafe, maybe the ecm has issues but I have given up because I’m absolutely sick of messing with it. I know it won’t leave me stranded so to Hell w/ it. Good luck w/ yours. I’m curious to see where it goes

 

Well don't be bashful

Let's hear what you think it might be.

I can return the injectors and save that money

 

Have you gone through and checked harness connections and cleaned up grounds, etc.? It would be silly if this was caused by a corroded or loose connection somewhere...silly, but a good outcome if found before pulling too much hair out.

FWIW, I’ve used wd40 in the past to temporarily drive water out of spark plug wire...can be a helpful diagnostic aid...also works to temporarily quiet something that squeaks, helping ID a faulty component.

 

I have not
the connections for that cylinder injector are hiding under the intake

FWIW I stuck the mechanics stethoscope to several injectors and they all made similar noises

I also found out that if you unplug the coil from the harness the truck will quit. Guess 2 dead cylinders is too much? Or is that a sign of something else?

On a positive note, the injectors passed over the house and went to Memphis and are having a layover there now

 

To be clear, when you're under the hood and listening to injectors, is it misfiring during the inspection? I'm stubbornly thinking that it's a bad plug wire or plug. Did you ever have a chance to look/listen for arching under the hood while it misses?

I used to have a VW which was notorious for ignition coil failures, most noticeable in rainy weather. It was also a royal pain to remove the plug wires without damaging them, unless you had the VW plug wire tool (still have mine somewhere). The diagnostic trick was to look under the hood in the dark, and gently mist the coil and wires with water, which would often cause arching, thus revealing the short. I would use the wd40 trick I mentioned above to buy time until I could afford a replacement coil. The coils were encased in plastic, which would develop hairline cracks with age, allowing moisture inside, causing it to short to ground. Some of the VW guys even advocated baking the coil in the oven at a low temp to thoroughly dry it out, then slather epoxy over the casing to seal it....coil was about $100 from dealer.

I had a similar issue to yours in the Tacoma after washing the engine bay; intermittent misfire in a single cylinder. It was caused by carbon tracking on the coil pack tube (that goes into the valve cover). Must have forced some water and dirt into the tube, allowing it to short. Cleaned it up, replaced the rubber seals, and the misfire hasn't returned.

 

Perhaps the ignition system has a problem. AmherstAndy is on the right track.

 

I did run it at night in the driveway with no lights on, I did not spray it with water but I can. What does "carbon tracking" look like on inside of tube? I shined light down tube and I can't see anything that would indicate discharge to tube. If it was a problem on the #5 coil that also feeds to #2 it should affect both cylinders, correct?
I can pull the old set of wires that came off and swap a couple onto truck and see if that makes any difference.

Yes missing when injector "clicking". I put the end of the mechanic stethoscope on the exact same spot on each of the injectors I could get to and got same noise and cadence. I even pulled the plug wire for a couple of minutes and shut off and immediately pulled plug and it was dry (would think if injector firing it would have fuel on plug?)

Would that include cam position or crank position sensor?
Did some reading and searching of the net and those 2 came up

Also read where a vacuum leak could cause it and even though I checked for leaks and found none I considered buying links of the various size vacuum lines and just replacing all of them anyway. Relatively inexpensive and would not hurt to change them all anyway.

Rain cleared out so I can mess with it an hour or two after work again.

 

If it's misfiring during this test, then I don't know if spraying water will help, since this is intended to induce a misfire that's more likely to occur in damp conditions.

Here's a picture of carbon tracking on a plug; can also occur on the boot (tube) that attaches to the plug:

Depending on where the supposed short is occurring, it may or may not affect cyl 5, although you said earlier that the problem persisted when you swapped coils, so this seems less likely to me. Sounds like it could be restricted to the cyl 2 wire/boot/plug.

If you know them to be good wires, this is a great idea.

Sounds like a good test procedure; can't rule out a clogged injector, and this could be pretty solid evidence in favor of that. My gut feeling says the intermittence of the issue is more consistent with a spark problem than a fuel problem. I can certainly be wrong about this and am glad to know you have injectors on the way.

I'm not sure how a vac leak can cause a misfire in only one cylinder; maybe someone more knowledgeable will chime in. I would think that reading the plugs could provide clues here: does the plug from cyl 2 look like it's been running lean compared to other cylinders?

 

Im not saying this is the issue BUT i had something similar happen to my truck a year ago. I had a misfire and when i went for long drives truck would drive sluggish. I didnt get CEL. I proceeded to cleaning the MAF and nothing changed. Inspected plug wires and coil packs. Also cleaned them nothing. So finally pulled plugs and noticed that some of the spark plugs had missing electrodes so i replaced all of them and problem solved. The plugs i replaced werent old either. I think i might have broken them when i re gaped the plugs. Good luck

 

If there were a vacuum port on the intake leading to cylinder 2 and that's where the leak was, or if the intake manifold was loose near the #2 cylinder you could leak air there. Check that the intake manifold nuts/bolts holding it to the head are not loose. You could also have a vacuum leak from the o-ring/grommets of the injectors.

 

I sprayed carb cleaner all over that side of engine and if it is sucking air I did not find it

I did not see any carbon tracking on any of the plug (new one or old one) but not sure how you would tell on black rubber unless it is just jump out at you obvious

Of course it decides to run fine while I am messing with it this afternoon.

I tried to ohm the plug wire and nothing at 200ohms, so I tried one of the old wires and nothing. Unless I needed to set the meter higher 2K?
I even took a pair of cutters and cut both ends off the wire (Denso best as I can tell) and nothing still on meter. I do have one of those spark checker light up in line gizmos and got it somehow on plug down in that hole and both wires lit it up and it only missed when I pulled wire off of gizmo (killed spark to that cylinder)

Would not hurt to put new wires on it anyway so I may just grab a set on the way home and eliminate that from the equation

Andy I did not compare plugs but plug I pulled was a tan and from the way I understand "normal". Not clean white which I understand to show lean and not black/sooted up to indicate rich.
I can take a pic of the plug and try to post it tomorrow evening if that would help?
Maybe it would not be a great indicator since it was intermittent issue and not constant when I pulled plug?

 

I don’t want to advocate spending money on the parts cannon, but if you need new plug wires anyway, might as well. I have one coil per plug for my 2003 2.7 L; they look different and the carbon tracking was very obvious in my case.

You’ll get this solved...I don’t know if I can offer any fresh suggestions, but I’m happy to do my best if you want to bounce some more ideas around.

 

The resistance spec of spark plug wires is usually maximum of 25k Ohms (not sure if your exact year is much different), so you should check with your meter set to something higher, like 200k range. And compare to the other wires. the longer wires should be slightly higher but all in the same ballpark.

Did you check the resistance of the injector, you know, with engine off and disconnected, measure resistance across terminals? For my 1996 it says 13.8 Ohms at 68°F. It would not tell you if there is a clog, but it might tell you if there is a problem with the tiny coil inside. You can compare resistance to the other injectors too.

 

These grommets, the ones in the head, how tight is the injector supposed to fit in there? I noticed the head shop didn’t replace them when they overhauled it and my injectors just kinda easily slid in there.... I have a random miss as well but isn’t setting any codes. And my miss comes and goes. Truck ran crappy today but ran so well yesterday I wanted to drive it across the country. Really aggravating

 

Toyota marks the o-ring and insulator are non-reusable parts, but the grommet can be reused. But in the injector installation section the diagram says "new grommet". I'd say why not just replace the grommets unless they were replaced very recently?

You should be able to rotate the injectors, but I don't think there should be any play other than the rotation. This might be more of a check for when you are installing them to be sure the o-rings are in place properly. I'd be hesitant to try to rotate injectors that have been installed for a while because the o-rings might be brittle and break, unless you are about to replace them anyway.

 

Those 3.4 engines call for the double electrode plug, at least the one in my old T-100 did. Is that the type of plug you are using? Those are pretty solid engines if you keep up on the maintenance so my GUESS is that a compression check will come back ok, but I'd get that done to rule it out. Also, since it's intermittent, I wouldn't think it would be a compression problem.
How many miles are on the truck?