Discussion on all cylinders misfiring

I am working on a 2004 DC with 275K miles that I recently acquired. When I went to buy the truck the owner disclosed it had a CEL for misfires. I ran the codes and saw codes for a misfire at all 8 cylinders as well as generic multiple cylinder misfires detected. I still drove it 400 miles home and to my surprise the fuel trims stayed steady as I watched them like a hawk in the Torque app on the drive.

Now I am trying to figure out what event(s) are causing the misfires.

It detects far more misfires at idle than it does underload. This has me perplexed since my Land Cruiser 2UZ only seemed to ever detect misfires underload.

Nonetheless, I wanted to see the misfires for myself since there really isn't any detectable seat of the pants misfires and hooked up TechStream:


I know the MAF is critical to a smooth running 2UZ and while I haven’t cleaned it, the volume reading and temperature seem reasonable, so I don’t expect cleaning the MAF to fix the misfires.

The previous owner did admit to recently replacing the spark plugs and ignition coils (and throwing away the OE coils ). The plugs were a basic Autolite and I assume the coils are all generic parts store. I replaced the plugs with Denso Iridium plugs from Toyota and set the gap to 0.034”. Dang it, the low hanging fruit did NOT fix the misfires.

Replacing the coils with Denso should be my next step and needs done, but I have doubts that all 8 of the parts store coils would be bad out of the box (but maybe not). I have very little personal experience with parts store coils. I may swap a bank of coils with the Denso’s in my Land Cruiser for science.

What else can cause misfires to be detected? Would a timing belt that was not installed correctly or has jumped a tooth come across as a misfire? There is no record of a timing belt replacement on this truck, so I have the Aisin kit ready to go.

Any other thoughts from the hive?

 

Do you know if it was misfiring before the PO replaced the coils? It does seem odd that all the coils failed. Just spitballing, but I'd check grounds and possibly fuel.

 

If the timing belt was a single tooth off you would have a lot of misfires, and probably multiple cam position codes. Also super low power. (From what I've heard)

Does it feel like it's misfiring more at idle? I ask because these trucks are known for not always throwing codes, even when they're missing really badly, like you mentioned. When I had an incident with bad gas, the truck wouldn't throw a code until I did multiple full-throttle uphill pulls, missing so bad the whole truck was shaking. Maybe once the engine is revved up a bit the computer isn't realizing that it's missing? I'm not sure.

I think swapping some coils for your known good Densos might be a good next step. I'm not a diagnostic mechanic, but that makes sense to me considering how often people on here have misfires that are solved with a Denso coil.

 

Based on my perception of the PO I bet when the CEL came on, he went to the parts store to get it read and replaced the parts they suggested. He was certainly not a mechanic.

I picked up the truck with an empty fuel tank and have put two tanks of fuel through it. I don't think the fuel is the problem.

I cannot physically perceive any misfires. It idles very smooth.

The truck does seem low on power. I am very familiar with the 2UZ in a heavy 4speed Land Cruiser with 387k miles on it and this Tundra really seemed to struggle at highway speed in the Ozark Mountains on the drive home. No cam position codes are being thrown. I certainly do not detect any misfires on the highway.

 

Just to confirm, you cleared the CEL, and it came back on? Or did you acquire the truck with a CEL?

Also, how frequently does the misfire counter increase on techstream?

 

Fuel injectors and fuel filter maybe need replacing.

 

Misfire on every cylinder ... let me get you in the right mindset here, thinking at this from a diagnostic perspective. And also issue you a warning, namely the first point in the 2nd set of bullets here...

Clearly you need to think about things that would cause fuckups across EVERY cylinder here, so you know it's not going to be individual things like:

• Fuel injectors ... no way every injector is clogged/malfunctioning at once, you're more likely to see hemispheric/bank-specific misfires
• Coil packs ... even if he used shit coil packs from LAPS, highly unlikely more than 2-3 are inadequate.
• Intake gasket leak ... it's possible no gaskets, wrong gasket, or poorly installed gaskets but again, that would be hemispheric/bank specific more than anything

Things you could be looking at as the problem are more likely to be BEFORE or RELATED to mixture+combustion:

• TIMING ... this is the first place I'd be looking, and before driving it again, just to verify the belt isn't gonna snap, since previous owners can never seem to do it every 9yr/90k miles as instructed, and it snapping can boat-anchor your engine.
• Bad ground somewhere in the engine bay... could lead to misfires, but I'd expect to see it on cylinders as they're wired (on mine 1-4-6-7 and 2-3-5-8 are wired together IIRC), and you could run a temporary 8GA jumper from the battery to one or more ground points on/around the block to see if it stops
• Failing fuel pump ... unlikely if you see adequate, consistent pressure, but based on the infrequency of misfires, maybe that is happening; pump may not even be failing, pickup/delivery tube could be loose, but main point: inadequate fuel delivery would 100% cause misfires on all cylinder when it's choking, I'd expect it to be worse on one side than the other.
• Fuel pressure regulator ... It's on the fuel rail directly, and I cant imagine it's bad, just getting you thinking here...
• Invalid air intake information, i.e. MAF is bad; I'd clean it with CRC MAF cleaner just for the hell of it.
• Bad/miscalibrated throttle position sensor
• Bad ECU

The latter of those you're kinda hoping it isn't, but ... if you happen to have a JY nearby and could get a part# matching ECU, that could be an easy test to rule that out. I believe even the FSM lists it as a possible cause for multi-misfire.

What if you run the A/C full blast (maybe with the heat one so you're not freezing your ass off) so you're adding another 100-300rpm of load onto the engine?

If that seems to quell the misfire, once again, I'd be looking at timing belt/timing ASAP.

I'd still clean it. Takes 2 minutes of active time to clean, then let it return to ambient temp and reinstall.

You should've told him new OEM coils run $500, and you rarely ever have more than 1, maybe 2 go bad any short term interval, he would've probably been piiiiissed

Dude just threw away $100-200 someone else who would've known better would've paid. I'd be chewing out the asshole at the LAPS parts counter who talked him into buying all new coils!

Coil swap could be interesting. I'd almost guarantee that's not your problem, but if you have a way to eliminate anything above from the list, and it's that simple, hell, go for it.

Yes, bad timing could cause multi-misfire. So would a stretched belt. Have you pulled out the 10mm yet to loosen fasteners and and peek behind the timing cover yet? That would've been the 1st thing I did.

 

You really are an asshole_dog

(It's never the fuel filter!!)

 

Why not?

 

I have cleared the codes a few times. They always comeback very quick, weather the motor is hot or cold.

I don't have any definitive answer to the TechStream misfire counter, but the number of misfires continuously change every few seconds. When the misfire counter numbers go up, the CEL flashes as I would expect.

 

Why not the fuel filter? Probably because there's a sock on the pump itself to prevent any of the typical debris from even going far enough down the line to reach the fuel filter? It's never once on this forum been the fuel filter to date, at least not in my 4 years here. But plenty of poor souls have busted their knuckles and gotten gas dumped all over them trying to be like Charlie, finding the golden ticket that unlocks their ability to say, "AHA! FINALLY IT WAS THE FUCKING FUEL FILTER! HAHAHAHAHAHA!"

(Now watch, I say this, and some troll is gonna come along and try to say replacing the fuel filter fixed their issues...)

 

AC on had no affect on the misfires.

I did experiment with the injector volume flow in TechStream.
When injector volume was reduced it misfired more. When injector volume was increased the misfires were far fewer.



I'll get the MAF cleaned up and pull the cam gear cover to peak at the timing belt. PO owned the truck for 12yr/180k miles and claimed he never had the timing belt done but did have the water pump changed I am not currently driving this truck until I can get the timing belt changed. Hopefully I'll have time this weekend to knock it out.

PS - I did buy a fuel filter as part of my preventative maintenance

 

Well, I'd still check the timing belt ASAP, better safe than sorry, and lack of added load from the A/C isn't definitive timing isn't the issue, but I'm less inclined to think it's timing related based on that alone.

If I'm not mistaken, ECU (ECM, wtfever you like to use) is ultimately deciding how much fuel to spray based on how much oxygen it's sensing incoming (and the throttle position, I think these two are main factors?) so ...

If upping the fuel is reducing the misfires, I'm leaning toward:

• MAF
• Fuel pump dying a slow death/underperforming
• Maybe: ECU
• Maybe, but less likely: Vacuum leak (did you check all the houses? Vacuum routing info should be on a sticker attached to the hood...)
• Unlikely but possible: Fuel pressure regulator
• Unlikely but possible: Something related to throttle body/position/etc.

That's not to say it also can't be something electrical, but ... whatever it is would need to be something that'd have a larger impact on EVERY cylinder. So it's most likely going to be something that either supplies something to every cylinder, monitors what's going in, or controls every cylinder.

 

Isn’t the water pump driven off the timing belt (yes it is) Meaning shop could have skipped a tooth while changing the pump.

Also, easy enough to check compression on these engines.

 

I bought, and still have, a super clean low mile 2000 Ram 5.9 Magnum 4x4 I bought for penny’s because it had a misfire.

Previous owner said he did a “Tuneup” and it started to “run rough” so he took it to a shop and the shop told him the increased power from the tuneup must have caused the valve train to fail and it needed $3,500 in head work.

I got the truck home checked the plug wire routing, he crossed two wires. Switched them truck purred like a kitten.

 

Fuck that fuel filter.

 

I pulled back the timing gear cover and looked at the belt. The timing belt was glossy black and looked worn, but there were no signs of cracking or splitting. I didn't see any identifying marks on the belt, so I have no idea where it came from but I was pleasantly surprised to see it wasn't in shambles.

Cleaned the MAF, let it sit for awhile and fired up the truck. CEL still flashed (indicating active misfire) at idle.

I started inspecting wiring under the hood and noticed a few oddities. The ground for the AC compressor has been spliced and repaired with butt connectors and a ring terminal. The ground strap from the firewall to the back of the block was wadded up in the middle and wrapped in electrical tape. I am not sure what the purpose of this is. Negative battery terminal had been haphazardly repaired and the (-) to body ground was cut. I crimped a new lug to the negative battery cable, built a new 4awg (-) to body ground cable and fit them with a new negative terminal. Started the truck and the CEL stayed off while it warmed up in the driveway. I didn't scan for any pending codes, but this is the first time I have ever had the truck idle without a flashing or solid CEL.

The fuel vapor hose is very dry and hard as are the hoses hooked to the idle up valve on the power steering pump. Looks like I need to replace some vacuum lines.

 

One point on that -> Did you pull the negative battery cable for at least 10 minutes after cleaning the MAF? If not, do it now. You need to force the ECM/ECU to clear after something like that so it'll go into relearn for readiness. Expect it to potentially run like shit for a few.

On the vacuum lines, that's a good one, not only to check the ends (if they're cracked/leaking at the ends, it's typical, cut off 1/4", reseat), but also verify all are intact and hooked up correctly, there's a pair on the passenger side some people cross by accident.

But I think you may've found your issue? Sounds like someone was hacking on the wiring. Bad ground is definitely on the bullet list of things that can cause something like this above. This is why I reco running a temporary ground, just for shits n giggles if nothing else.

 

Fingers corssed!

 

Hello! Can you please tell me if you solved the issue? I have the same issue!

 

Here's a excerpt for his build thread that may be helpful

Which reiterates this point here

Project Gray Sky | 2004 DC 4x4 | Toyota Tundra Forum

 

You want to tell us whether you have the V6 or V8?

And if you have the V8, when was the last time the timing belt was changed? It needs to be changed every 10yr/100k miles.

 

Correcting the timing fixed all but two misfire codes; cylinders 2 and 3. These two cylinders have lower compression than the others. I don't recall the exact psi findings, but cylinders 2 and 3 had noticably lower readings. I suspect these two cylinders would have scoring on the walls if I stuck a bore scope in there since the PO let this truck get very, very, low on oil due to the oil filter adapter leaking.

I cannot feel the misfire whatsoever. In other 2uz equiped vehicles a misfire has always been obvious. At this point the truck is approaching 300k miles, still averages 15-16mpg, the fuel trims are constantly in check and it has far more power than my Land Cruiser with the same motor. Heck, the misfire codes clear themselves when in the Colorado high county I keep a close eye on everything and am just living with the 2 misfire codes since the truck runs so well.

 

Thank you all for the response. Most of my problem came after letting the truck sit for six months which led to the battery dyeing. After jumping it my system went haywire showing all cylinders misfiring. I have brought it to be worked on to numerous places and they all keep telling me it needs a new engine. It's a 2003 SR5 tundra V8 with 146k miles so I don't want to believe it. Issues I am having are cylinder misfire codes, 02 sensor codes, and low idle in park.

 

You probably don't need a new engine, and no reputable shop could tell you that without doing a compression/leakdown test. You should never let someone put a new engine into your truck without giving ample evidence as to why you need a new engine. Sounds like you need to find a new shop that specializes in Toyota, that's also not a dealership. They exist in most major cities.

We have a thread that will tell you a lot of info about your truck here: https://www.tundras.com/threads/so-you-wanna-buy-just-bought-a-1st-gen-tundra-eh.115928/

1st two replies are a community-generated compendium of everything we know, after years on this forum of people coming and going.

There are a few tidbits in there that could easily explain your issue:

• Rodents. They love to nest in these trucks. They love to chew up wiring and paper stuff. Some common places they like to get into include the airbox, where a piece of chewed up air filter getting stuck in the MAF could cause the ECU to misread airflow and set fuel too high/low causing misfires, for example. They love nesting on top of the gas tank, potentially chewing wiring going to the pump, fuel and evap hoses, which would interrupt fuel delivery, causing misfires. The wire sheaths on many vehicles are soy-based and some rats find that too tempting to not eat.
• Water leaks. Specifically, from cracked windshields and rust and A-pillar trim or seals leaking, can get into the ECU behind the glovebox, or directly into the back of the fusebox in the dash, causing multi-circuit issues.
• Grounds. These trucks are pretty well-documented for having corrosion inside the main power/ground cables, and if you're the kind of person who can't be bothered to put red/green felt rings around your terminals, and battery gasses escape at the terminals and corrode the outer part of your cable, that will spread thru the cables. Running a temporary (but substantial) ground from the battery to the engine block and the frame may be a quick test to see if poor grounding is your issue. But plenty have found their power cable rotten from the inside out.
• ETHANOL (/bad gas). If the truck sat for a long time, and you typically use the cheapest gas possible, and you did nothing to purge the tank after sitting for a long time, ethanol that's in most gas these days will absolutely congeal and jam up the fuel filter which exists on '00-'04 trucks, impeding fuel delivery to the fuel rail, resulting in low-fuel delivery, which will totally cause misfires on all cylinders (bad air/fuel ratio). Of course, you can test this theory by watching the fuel pressure as you rev the engine to ensure it stays above 40psi, but Toyota gave us no easy way to monitor fuel pressure on these trucks - if you had a way, this would be a no-brainer to rule out.

That last one is probably the easiest to check and despite the number of times you'll see me say on here, "It's never the fuel filter!", in a case like yours, it'd be extremely high on my list if you let the truck sit for more than a year without starting it, then fired it up without purging the tank.

But here's the thing ... :

• Expect to bust some knuckles. Hit the fittings with penetrant a few times/days in advance of changing it out so the two fittings on either side of the filter are hopefully ready to pop free.
• Expect to take some gas to the face. It happens. Anyone can do this job, but many here who've been there/done that have commented about cussing at the process.
• Don't use cheap fuel filters. I'd urge you to buy premium from the local dealership because Toyota designed the filter to be the best possible for their engine characteristics. We recently had this discussion on here, and others are using Wix filters w/o issues (yet).

What would I do with a vehicle that sat that long?

1. Get a mirror, inspect on top of the gas tank for signs of rodents: Chew marks on fittings/wires/tubes, dropping, shredded wire harnesses.
2. Open the air box, pop the filter out, look for signs of rodent activity.
3. Purge whatever gas remains in the tank. As much as possible, to empty the tank as much as you can.
4. With little/no gas in the tank, change the fuel filter out, now is the time (I'd start hitting its two fittings with penetrant ahead of time).
5. Get my 5gal gas can, and go to the nearest gas station that sells non-Ethanol gas, fill 'er up.
   
6. Go to the parts store, and get a bottle of HEET (the red bottle, specifically) and a bottle of Seafoam High-mile).
7. Add the HEET and Seafoam to the gas, then fill the truck up with the fresh gas.
8. Fire it up, and let the truck idle for 10-15 minutes, understanding this: When you lost power for so long, the ECU was forced to "re-learn" how to run, so it'll take a little while for it to get there.

 

Thank you for the reply! Very much appreciated. I wish you lived near Boston Mass so I could hire you. Do you or anyone else know of any reputable shops anywhere near Massachusetts?

 

I think @BroHon is a Masshole

 

@Jack McCarthy definitely is.

 

Miasshole, extraordinaire.
Band of the hand

 

Damnit - mis-ID that one. I meant Jack McCarthy. Apologies Brohon