misfire help request

2002 Tacoma 2.7L 4x4 Auto.

Recently I finally decided to tackle a leaky exhaust manifold and that job went fairly straight forward. A couple welds and new gaskets and it's back in shape again.

But shortly afterward (like a couple days) I developed a misfire problem. Drove the truck to my parents and shut it off. left about 15 minutes later and had a bad miss. Limped it home and it straightened out on the way. Drove it to work (60 miles round trip) and had no issues that night. Next day took it to the hardware store, worked fine on the way there. When I went to leave it was running rough again. I decided to drive it home anyway and about a mile into the trip it straightened out again and drove fine, but this time I got a CEL.

The codes are only for misfire on cylinder #1 and #4 and random misfires. I cleared the codes and they return eventually. The truck starts find cold. Once it warms up it will start missing and if I shut it off, wait a few minutes and restart it will miss. Sometimes it will work fine after driving it for a few minutes, other times it won't.



In the first image was the first time I was scanning the truck and this was with #1 and #4 ignition coils swapped (after getting the miss and reading the codes I switched those two coils) It looks like that coil is bad.
But then look at the second image, which is after a restart of the truck and both #1 and #4 are giving me some funky readout- which I don't know what that means. #2 and #3 are how I presume they should look.

Also, as side note, unplugging ignition coil #4 will stall the truck. Unplugging any other ignition coils just makes it run rougher.

I pulled #4 plug and it looked good- nice and tan and nothing broken or deformed. All the plugs have about 10K miles on them.

Ignition coils are expensive through the local auto parts store. I see I can buy four on Amazon for less than the cost of one locally. What is your opinion of different brands? My truck currently has 3 original coils and one denso... the denso is in cylinder #4.

Any chance this could be a fuel injector problem? How about a MAF? Looking at the scanner those components all seemed to be within range. My past experience with other vehicles is when a coil goes bad it doesn't just start working again all on it's own. But that is just my experience and I welcome other opinions.

This is not a "money is no object" situation. So spending $90 for one coils (which is outrageous cost for any coil- technology that hasn't changed in like almost 100 years) is not something I would prefer to do. I'm not just going to throw parts at it. I'm wondering if anyone has had identical symptoms and found a solution for the issue.

Some other recent threads I have read do not seem to have the identical problem.

Any help is appreciated.

 

Many times you won't find 'identical' symptoms because people use different words to describe the same things. I wouldn't try to hunt down identical scenarios.
You're gonna have to do some testing and troubleshooting. I also don't believe in shotgunning new parts at a vehicle just to see if it'll fix it. That snap-on scanner tool is pretty freaking nice. You have access to a lot of troubleshooting data with that thing.
General things, non Denso ignition coils have shown time and time again to be unreliable. Doesn't mean yours aren't working right, I'm just saying. On Toyota electronics and ignition systems, it is definitely recommended to use the OEM components or at least components made by the company that makes them for Toyota. Regarding the coil packs, that would be Denso.
Did you happen to get pics of the spark plugs you looked at? Post the pics if you did. Was the plug in the misfire cylinder any cleaner/newer looking than the others?
Injectors not firing correctly can also cause a misfire. What are the specific DTCs you have at the moment?

 

Check for cracks in the intake tube, It absolutely could be fuel injectors. How many miles? I'd start with a compression test on a 2.7 for sure.

 

For full disclosure, I purchased the truck in the fall of 2018 with a diagnosed cracked head issue. I towed the truck home and disassembled the engine to find it was just a blown head gasket. The head was decked for good measure, valves were lapped, shims were adjusted, new OEM gaskets, plugs, seals, o-rings, air filter, oil change, coolant flush, and a bunch of other odds and ends. I checked compression this past summer and I was in the high 150's to low 170's in all cylinders. I could check this again, and will just because I can. I think the part that some are missing is that this problem comes and goes. Even while it's running.

 

I had the same problem. I changed spark plugs and switched coils and got the same CEL codes. I then purchased refurbished injectors and replaced them. Since then no problems. (btw, my problem started to happen after hitting 200k). Good luck!

 

Yeah, it's sort of intermittent. I can probably make it happen by running it up to temp, shutting it off, waiting a few minutes, and then restart the engine.

My truck has over 233,000 miles and did the head work at 224K. Recent work was fairly minimal, but I did have the intake tube off a couple times. I have gone over all the things I removed during the most recent work and inspected things I've touched. I will probably do some more inspection tomorrow. The weird readings I'm getting with the scan tool are what is giving me reason to believe it's some sort of electrical problem, whether that is a coil or fuel injector I can not be sure. I may try to make a "scope" to listen to the fuel injectors to see if that helps me locate my problems.

Good deal, what injectors did you purchase and from where?

Thanks!

 

That's why the guy earlier said coolant and you tried to make him feel dumb about it. It's common with a cracked head or gasket to get misfires exactly as you describe. I think I'd start with one of those exhaust gas sniffer things that detect coolant.

 

Did no one read the part where I stated that I repaired the bad head gasket and have been driving it for nearly 10,000 miles without any issues? And I did that over a year ago.

 

I purchased my injectors from a company on eBay that sells refurbished Denso injectors. The company was out of Hollywood Ca.

 

tcervinsky, this could be the company that I used. https://www.ebay.com/ulk/itm/312832322968

Best of luck!

 

Dude just because you did a head gasket doesnt mean you don't have a craved head or valve seat.. Youre asking for help but talking to the people who have personally fixed multiple engines with your issue like we are clueless. 2.7 heads are known to crack. compression test and leak down will save you money and time.

 

Again, I am not trying to be rude, but if you took the time to read complete sentences you would see that I told everyone the head has been machined, the valves have been lapped, the valve shims have been adjusted, etc, etc,... It's not my first rodeo either. I have built many engines from the ground up. I am aware probably far more than you what the symptoms of a leaky head is. I'm guessing you don't know that a cracked head will leak coolant or oil, sometimes they will mix, sometimes they will just enter the combustion chamber and burn up. Either way you will notice symptoms that accompany them, such as loss of coolant, white milky oil, blue smoke from the exhaust, or a sweet smelling exhaust if it's only burning coolant. I have none of these other symptoms.

I have belonged to many forums in my life; for my Jeeps, Audi's, VW, Fords, and Chevy's. I have never come across a group of people so rude as I have found here. It's really astonishing that anyone would want to use this site.

I came here looking for advice from someone who's owned their Tacoma for more than a couple months and have some experience with symptoms as I described I am having. But a few seem to want to run off in other tangents and waste time. Get out from behind your computer and go out and find out what it is like to have to work for you money and what it's like to support yourself instead of living off your parents.

Beat it kid.

 

as you well know, intermitants like this are difficult to trace down. I find it odd that the motor stalls when #4 coil is removed from the system. I looked at a wiring diagram hoping that there was something special and unique for the wiring for the #4 coil... like it was a series feed for all of the rest of the coils but it isnt wired that way. I sure does sound like coil(s), either spark or injectors, are breaking down. Short of using a PICO scope and actually watching the primary winding voltages (coil and injectors) or paying someone to do this, you are going to have to, and I HATE this, start to swap parts around, again, to see if the miss follows. Have you wiggle tested the harness(s)?
Time graph the ECT via OBDII and see if that changes and do the same for the A/F sensor and O2 sensor.

 

LMAO I have owned over 50 toyota pickups, I have personally swapped at least 8 bad 2.7s I have personally swappend and wired 5 3.4 conversions and a 1uz into a 4runner.. The ONLY person here that lacks any kind of knowledge would be YOU sir. you are asking for help with misfire issues..... I currently own 4 Toyota's 82 sr5 pickup 4x4, 84 sr5 pickup 4x4, my 2002 tacoma as well as a 2004 4Runner. I have owned between 1 and 10 toyotas at any given moment for the last 12 years.. Try again

 

it doesnt matter if you machined the head 10k ago, its still an old head and they are still prone to cracking.

All I am trying to say is a compression test is free if you have the tools and rules that out. Is that really hard for you to understand?

 

Not trying to be rude? Maybe you dont have to try, bc this was a dickhead response

No ones making you stay here

 

I'm sure he has plenty of knowledge but who wants to help an ass like that? Gonna be hard to get help when he act like nobody can teach him anything about troubleshooting and he ask for a fix based on 'exact symptoms' smh.... That doesn't sound like someone confident in the troubleshooting side. Which would be expected. His taco's problem is definitely not an easy one but talking to folks on here like he did/does will help keep folks from wanting to try and help.
This is actually one of the most helpful and courteous forums around

 

And this is type of group here that we'd all be cool with him just coming back and talking to us like fellow Yota gearheads and water under the bridge. Not many forums like that. He may have had shitty experiences on other forums and thought he would say it the way he did to weed out the ones that couldn't really help.
But that's prolly not the best way to ask for help if you're like me you hate even having to ask for help because I feel like I can't explain what I need clearly enough.
I'm actually really curious about what he has going on, it's not a super common issue but definitely can be hard to troubleshoot.
Anywho back to our regular programming

 

That's what I'm getting at. There is so many things that can cause his issue and I tend to test whatever I can before spending money. New head work can cause bottom ends to fail, rings or bearings ETC. compression test is free, coil packs and injectors aren't.