2007 random cylinder misfire

2007 Toyota tundra 5.7 l 308000 miles. Random Cylinder misfire. Number 4 and number 6. I changed all the plugs, I changed all the coils. I put dialectric grease on #4 and #6 coils. when I clear the codes, It runs better. Then the codes come up, P0300, Random multiple cylinder misfire. Po304, Cylinder 4 misfire, po306 Cylinder 6 misfire. Runs rough. Then I clear the codes and it runs OK again. I also put a whole tank of high test gas with sea foam in it. What's your next guess?

 

Why keep with the guessing? Why not some diagnostic testing like a compression test (may be a HG failure between cyls 4 and 6), and a fuel pressure test next?

Did you notice any visual difference between the #4 and #6 spark plugs vs. all the others?

 

Does it run better when the engine is cold?

 

I did a compression test also. I tested number 4, 5, 6 and cylinder one. All of them were about the same compression between a 110 to 118. No visual difference between spark plugs That I can see. What is HG failure?

 

HG = head gasket. Was thinking maybe it had blown out between cylinders 4 and 6 causing low compression in both, but your compression test seems to eliminate that possibility.

Any drop in the coolant level?

 

Funny you ask, because YES. There is a small leak in the coolant. I cannot find it. I looked closely everywhere and I don't see where the antifreeze is coming out. Every time I stop the truck at a parking spot and come back there's nothing even on the ground. And I did find out from a Toyota mechanic that a drop in the fluids Can cause the computer to go crazy with a sensor and cause a engine misfire. I add about 1/4 of a gallon Of antifreeze everyday. I don't want to buy a radiator unless I know where the leak is because it may not be in the radiator. But even when I clear the codes and it runs better it still feels like there's at least one cylinder that is misfiring and it's got to be either 4 or 6. I tested for spark on cylinder number 6 and there was. I could not test for spark on cylinder number 4 because my tester wouldn't reach around with the coil Where it was. Hard to explain.

 

Do you have access to a cooling system pressure tester? If you do, I’d pressurize the system for a while, remove coils and plugs for 4 + 6, and either scope the cylinders for coolant, or hold a white paper towel above the spark plug tubes and have an assistant crank the engine (disconnect all remaining coils first so it doesn’t start) to see if you get any pink mist. It takes very little coolant weeping into a cylinder to cause a misfire.

 

Wow, That's a good idea, but, crap! I sure hope it aint that! I will try that. Feel free to let me know if you have any other ideas. Thank you.

 

Yup, a couple injectors or a vacuum leak would be easier on the wallet, for sure. Since you are loosing coolant though, better to chase that before swapping or replacing injectors.

 

small?

The original spark plugs you took out, where they oily/sooty or shiny and clean? Any amount of coolant in cylinder will clean it down to the metal.

Did you do combustion leak test? Amazon has kits for ~$20-30.

 

When I had a misfire on mine, first I pull all the plugs and coil out and cleaned them, swapped spots. Then it came back couple days later, and obvious oil leak onto two of the sparkplugs, location relate to the misfiring cylinder, so I decide to replace the valve cover gaskets, SP tube seals, and some brand new SPs, also did the PCV valve at the same time. After all those, it fixed my issue.

 

I would drop the skid plate for a few days, and see if you get any drops. Another issue may be the intake valley leak, look it up on youtube, but I would assume coolant is gerting in the cylinders on that side... Only way to know is pull the intake plenum... When my water pump went, it showed signs... when it went it took the radiator with it, and that was more apparent than the pump. Another option would be check your heater core and see if its leaking out of there.

 

@Goldeneagle65 did you find your coolant leak? I’m having all the exact same symptoms as you…anyone know if a coolant leak in the valley under the air intake can allow coolant to weep into the cylinders?

 

Can't see anyway that it could. It runs down the back of the block and you can usually spot it by shining light under the intake.

 

@Trident thanks for the reply. The shop is going to check under the intake next. In this thread it’s mentioned a coolant leak will cause a sensor to throw misfire codes, have you heard of that? What about the SAIS system? The SAIS valves are there at the back of the valley, could coolant enter there is the SAIS is failing?

 

@Goldeneagle65 @ landphil and @Wynnded because you've been a great help in the past , Y'all left off of this too soon. I'm having an eerily similar situation over the last couple of months. I have 385,000 miles on my 5.7 2007 and had I not put all of those miles on it, I probably would not have noticed a very faint misfire for about ten seconds after cold or lukewarm start several weeks ago. I keep up on all the change intervals on everything and am HUGE on OEM parts but I have let the plugs go to about 130K, 5K overdue which I don't think is an issue.

Like I said, the slight chug would always quickly fade but twice had a heavy misfire and then the CEL, 4LO (I think) and maybe VSC would flash but no limp mode. I did take it to O'Reiley's and the scan showed active misfire on cylinder 2 and I think he said it was also in the code history. I don't have a reader so I would unplug the negative on the battery for a few minutes to reset and I did replace the plugs just over a week ago. I tried to tell myself it fixed the problem, but it seemed to linger ever so faint.

Last night after returning home from pulling an approx. 5,000lb trailer for three hours, I dropped the trailer, let the truck sit for two hours and when I returned to go in town, it had a mis that it did not come out of in the 12 mile drive.

This a.m., I'm going to swap the coil, have the store scan the code try some fuel injector cleaner and hope I can get back to Cincinnati for the work week and get this figured out.

So here's where it gets interesting: When I changed the plugs, I changed #2 first and numbered each plug per cylinder with a Sharpie and set them aside for possible future reference. They're in Ohio and I'll look at them this evening but it seems like #2 was shiney clean whereas the others had normal apearance. AND, in the last two months I've noticed a very small consumption of antifreeze with occasional slight odor of antifreeze with no apparent loss of coolant on the outside. Only the resivoir was down and I filled it back to the line once. I atribbuted it to a couple long trips pulling the 5,000 lb. trailer, the fifth wheel and some romping on the sand dunes in Michigan.

I've got to believe there is coolant leaking into #2 cylinder, especially after running so well pulling the trailer last night, letting it sit 2 hours and then the dramatic misfire. I think the white paper towel in the spark plug tube test is in order this evening and I'm pretty sure it is going to reveal an issue. I want to get my thoughts in order ahead of time, but does anyone know of possible causes for coolant leaks into a cylinder on the 5.7?

Thanks in advance for the help and I hope we can help someone else in the future.

 

I ended up selling mine, took a loss…I chased those misfires for months, replaced all the pcv hoses (found some cracked) hoping that was it, replaced the crankshaft position sensor, put new CATs on the driver side as the front one had collapsed and hoped that was is it, had all the fuel injectors cleaning and new gaskets, fixed a coolant leak under the intake…always came back. I finally invested in a bore scope and cylinder 7 had oil seepage and cylinder 8’s piston had some shiny spots which typically means coolant. I showed all this to the buyer who runs a mechanic shop on a Marine base. It ran so strong which was frustrating…just rough starts. I miss that Sequoia still, loves it!

 

I'm inclined to think that there is the possibility of a coolant leak of the head gasket from the water jacket to the combustion chamber.

 

@Wynnded I think you are going to be correct. I wanted to pull the plugs, slip white paper towel down the spark plug tube and roll it over this a.m. to see if any of them come out with pink, especially cylinder 2. It was cool and raining so I did not do this as planned BUT, when I started the truck, there was an enormous amount of steam from the exhaust, probably amplified by the cool, wet morning air. I do believe I smelled antifreeze. I slipped down to my son in law's 2014 and fired it up for comparison. It too produced steam at idle, but not to the degree that mine did. So I parked it in our shop when I got to work so I can do the white paper towel test this afternoon. Pretty sure it's going to yield results.

Years ago, around 250K, I did replace the air switching valve under the intake. I cannot remember if there is a water passage between the head and intake but if there is, I'm praying to God this is where the issue is and not a leak in the combustion chamber. The coolant system doesn't over pressurize so I'm hoping this could indeed be the culprit.

I'll probably go as far as I need to to resolve this issue as I am not ready to replace the truck yet- save this current issue, it looks and runs too good to replace, plus I have a 2022 Camry we bought last year that needs to pay off before adding another payment.

I probably shouldn't have taken the old man up on the sand dunes in July. I just can't back down from a challenging hill and I push it until I make it. 4LO, 3rd gear and pedal to the floor, bouncing off the rev limiter just like every other year. I suppose it's no different than myself: at 50+, I've learned to respect my age and don't do some of those things I used to do and get away with. At nearly 400K miles, I'm thinking the same rule applies.

More to come... Thanks in advance for the help.

Steve

 

@Wynnded Man I wish I could say you were wrong. Didn't even have to use the paper towel, I could see the coolant laying on top of the piston when I took #2 spark plug out. Went ahead and did the towel test which only confirmed what I was seeing.

Now to decide what to do. Should I try to do the repairs myself or just get another used motor and throw it in. I really like this truck and have it how I always wanted it noting the Sequoia transfer case and most recently the 38 gallon fuel tank swap. Air bags with on board compressor, sound system just the way I want it, cosmetically in great shape, I could go on. Oh, and most importantly, NO MONTHLY PAYMENTS!

In your opinion without seeing it torn down, is it feasible to repair this engine assuming a head gasket and tons of labor are all that is needed? I can assure you this motor has never overheated so I can't see where the head could be warped. No doubt, this truck has not been treated like the average truck and has seen a lot of rough action, but has without question been better maintained than most. I do have the six volume OEM Tundra shop manuals to help guide me through the process so I have that in my favor.

What would you do?

 

Ya, I feel for you. I wish that it could've been something far less involved to resolve.

I'm just a shadetree level mechanic. I don't know that I'd want to dig into the engine myself without someone more experienced looking over my shoulder. That and not having a place to do the work. I might investigate how difficult it would be to source another engine for a comfortable price. But then again, I don't have the space for an engine swap. If you chose to pull the heads yourself, you'd want to consider what else would be wise to also replace, i. e. timing guides/chains, water pump, doing one side or both. Dig through the manuals that you have to try to get an idea what's involved with each path you've supposed. You have the equipment, motivation, skills, confidence? There may be some videos out there to give perspective. Ask several mechanics what they'd rather tackle. As a matter of fact, there are several here on the forum...

 

Well, I dunno @Wynnded . The thing is that everything else is in such good shape on the truck, but man, close to 400K miles. Steering is perfect, transmission perfect, interior and body in excellent shape. If I replace the truck, it'll be a 2013 or older CrewMax, swap in the Sequoia transfer, 38 gallon fuel tank and then I'm going to be tempted to do something real dumb like graft in the long bed from my DCLB truck on the CrewMax. I can't trust myself for that.

I'd like to hear input from someone like @ViktorG about the worthiness of attempting the work to replace the head gasket(s). How risky is it that it'll go again or could there be other underlying issues that I could miss or will it be good as new. Like I said, I do have the OEM 2007 Tundra Repair Manuals so I shouldn't miss details like procedure for properly torquing the head bolts and related parts.

I'll see what I can find on the forums about head gasket replacing. Thank you again for the help!

 

Looks like I'm going to dive into replacing the head gaskets. I just can't let the truck go. Prolly be a three week+ project for me with my work schedule but I'll post how things go and list parts, gaskets and time.

I'll plan on not replacing the timing chains or guides unless I see something not good. I've had a water pump, belt and tensioner for about a year with intentions of replacing them out of good measure ahead of a failure. I'll put those on and possibly the fan mount although it is only a year old. It was a real pain to replace at the time.

 

If this were my truck, at that mileage, I would put a low mile used engine into it and call it a day.

 

@ViktorG If I can find a good deal, I might just go that way. Can you tell me what years are compatible to swap into the '07? I'd probably go with a newer year. I think you and I have similar trucks minus the lift - dark grey 2007 DCLB 5.7.

Thank you for the input!

 

Any 2007-2021 5.7L will be a direct bolt in. Toyota changed the valvetrain in the newer production models a little bit and possibly some other minor things, not sure exactly which year, but it will not affect how the engine fits and runs in your truck.
DCLB is a beast, lots of space for my family of 5 and all the cargo.

 

@ViktorG Quick Question: I've elected to go ahead and tear down the engine in the truck, already got started. I have the heat shields off and cats off of the exhaust manifolds and am wondering if I can remove the heads leaving the manifolds on. I'm thinking they could remain on and still be able to remove the heads. I already know those studs are a nightmare to get to in the truck. What say you?

Also, any reason not to trust a Fel Pro head gasket kit over OEM gaskets?

I've got a plan for replacing my Tundra with a 2013 or older with less than 130K miles so I can keep my goodies from this one plus probably do something else dumb with it...

Thanks in advance.

 

I’ve never taken the heads off with the engine in the truck, so don’t know about any clearance issues etc.
I would personally only use oem head gaskets and other seals, Toyota sells a top end engine seal kit for a reasonable price.

 

@ViktorG I didn't realize Toyota had a top engine seal kit, so I will definitely be going that route, thank you for that.

Staying true to the words I live by, "Give the hardest job to the laziest guy in the shop, you'll find the easiest way to do it", I'm going to try leaving the manifolds on the heads and see if it is a go. I'll be sure to share everything on this forum to help others. I've got to believe that this will become more common as these engines get older.

 

Captain's Log - Day seven of my head gasket captivity: So I've got about 19 hours clocked on this project so far and I have the heads ready to come off next. I'm done working on it for the next ten days as I'll be away on a business trip, but I want to give an update sooner so y'all don't think I lost heart and gave up.

Things are going remarkably well, made a couple tools to remove the harmonic balancer and be able to properly retorque it. Interior of the engine has a super light amber film of varnish which I'm quite pleased to see, and no visible wear on the timing chain tensioners and guides. At 385,000 miles, Thank You Castrol. Note there was a slight buildup on the extremities of the timing chain cover that I'll attribute to those areas having a cooler surface because they are away from the warmer combustion areas and exposed to cool air at the front of the motor.

I'm taking my time to tag and bag everything, no loose parts or bolts laying around whatsoever. Also individually bagged and identified each rocker and valve cap per their valve. I've bagged most of the internal parts as they came off to keep them clean because I do not intend to solvent wash everything unless needed. I purchased two plastic totes designed for under bed storage so I could keep the assembled cam plate protected from dirt and keep all related head components together per their head. I did not do a complete teardown on the cam plate, but rather left the cams and sprockets intact, removing only the bolts anchoring it to the head. I did "detorque" those bolts in proper sequence in two stages as noted in the shop manual before completely removing them, again, leaving the other camshaft bearing cap bolts intact with the intent of only torquing the bolts I removed when I reinstall the cam plates. I'd be curious to know how @ViktorG feels about this for the sake of others that will surely be following this thread when their time comes, so please do comment whether good or bad. Before I started, I watched a couple lengthy videos on YouTube of tearing down the 5.7. which is where I got this idea but niether of those engines were salvaged and they did not do the diligence that I'm doing here probably for that reason. The videos are extremely helpful to understand the teardown process, even over using the repair manuals. Also note that I carefully marked the timing chain and sprockets in addition to the factory markings to be certain to reassemble them correctly.

Worth noting is that there is seepage around the plate on top of the block under the intake. I was not aware of this as it never dripped anywhere I parked the truck. It was clear at 250,000 miles when I replaced the air switching valve. I know this is not an uncommon issue, but I think it indicates the overall condition of the gaskets related to the cooling system. At least with this, I wouldn't expect a catastrophic failure like the head gasket.

I'll assess the heads after I return and then verify it is time to order gaskets or do as Viktor suggested and buy another motor. I'll only check them for straightness and clean them unless someone notes there is something else that should be done. I'm hoping to see an obvious compromise on the gasket that clearly identifies the gasket as the problem, we'll see about that.

One thing's for sure, this ain't no small block Chevy and it ain't for the faint of heart. Before I started, I figured it would be a 60 hour job for me and I'm on track for that so far.

More to come...