Cylinder 1&3 Misfire - Coil packs replaced still CEL (2 Viewers)

[bajaphile]

Thank you very much for your thoughtful and thorough replies @2001LC & @Julian Stead .

First off, yes, the motor is a VVTi motor.

To tell you the truth, I have not gone and inspected the other spark plugs as well as testing other coils. I've been focused simply on the 3 & 5 cylinders. I think it is indeed time to move in that direction.

I'll go and inspect for any intake leaks at the manifold gasket. That is a good idea. I actually have a smoke machine, which I can attach to the TB and check for any leaks.

As far as me mentioning that the AF sensors, I was more just checking that they were original Toyota's, appeared not to be replaced, and the truck having 150k on it. My main purpose of that statement was to question weather or not these sensors are good for 150k+ miles, or should I dive deeper into them. Also, from what I can find, the FSM only shows how to test the heater circuit but not the actual functionality of them?

I've removed and had several injectors serviced through the years, obviously during head gasket jobs, and believe that is a good way forward as well.

Thanks for the help, I'll continue to keep this thread updated for future reference.

 

[Spike555]

Well our nearest and most used gas station is a Shell, which is in my opinion the highest quality here. I guess I can try some injector cleaner. I'm still not fully sold on that being the issue. I'm still having a hard time understanding why it would be on 2 cylinders.

I get that, but it will take a few thousand miles of Top Tier fuel alone, add some MMO to each tank until the bottle is gone, buy the 32oz bottle.
Also E-85 is a great injector cleaner, run it until the low fuel light comes on, then add 5gal of E-85, drive it like your stole it, then fill it up with premium.

 

[bajaphile]

Well, I called a local mechanic who've I known since I was a kid and my dad uses from time to time... He said he'd do a full diagnostics for me for $120... So rather than buying a compression kit, fuel pressure kit and leak down kit, I just had him go for it.

Result: Probable head gasket failure at 3 & 5. Compression on 3 & 5 are at 90 psi, the rest are at ~170 psi. He mentioned that it could potentially be burnt valves at both cylinders, but I couldn't imagine that being the case. The head gasket failure would mean that it was between cylinders and not involving a water jacket.

Looks like I'll be tearing down the motor soon. Any good HG writeups for tips and tricks on the 2UZ-FE would be helpful. Guess I'll start reading through the FSM and tracking down parts.

 

[Spike555]

Well poop. That sucks.

 

[bajaphile]

@2001LC @Julian Stead

Any other tricks/ideas to verify if it is HG or a possible valve issue?

Kind of annoying now that I think about it -- this guy takes my money but doesn't give me the exact issue... I'm still not 100% certain its the HG. Could valves go bad on 2 cylinders at the same time? Wouldn't compression be @ 0psi with bad valves?

The fact that both cylinders have the same low psi makes me think they are connected via breached HG!

Still haven't found a very good writeup... I guess its just like any other HG job though... would be nice to see some problem areas though ahead of time!

 

[DirtDawg]

Did he check compression correctly? HG dont go commonly on these engines, and honestly doesnt sound like your issue.

 

[bajaphile]

Did he check compression correctly? HG dont go commonly on these engines, and honestly doesnt sound like your issue.

I sure hope so... I mean he's 60 years old and took the shop over from his father who had been a mechanic his whole life as well at the same location.

Just seems odd that TWO adjacent cylinders would have valve issues...

 

[DirtDawg]

I sure hope so... I mean he's 60 years old and took the shop over from his father who had been a mechanic his whole life as well at the same location.

Just seems odd that TWO adjacent cylinders would have valve issues...

I almost guarantee the low compression on those two cylinders was from fuel washout on the rings, aka dry rings. Drop a bit of oil in there and you should see good compression across the board. People have gotten similar low readings on the 2UZ but just found out that the rings needed oil.

This mechanic should have known that if hes as seasoned as you say... But I almost guarantee it isnt a head gasket.

 

[DirtDawg]

If he checked compression on a cold engine it can give false readings. The FSM clearly states to start and warm up the engine before doing a compression test. It then goes on to state that if the reading is lower than the spec, to add a drop or two of oil and take the measurement again.

I would get compression rechecked if you are really worried about it by a mechanic that will do it correctly. Even bring the FSM page in if you are worried. But honestly I think your fine in the HG department.

 

[bajaphile]

I sure hope you're right about it not being a head gasket... As usual I'll probably just go buy another compression test kit and do it myself. I'd really like to put #3 @ TDC and pressurize it using shop air and see if #5 has air coming out of it... That would confirm some things for me.

He said he first used the Toyota scan tool and said all sensors and everything else was good. He did mention he rarely does compression tests on these motors. (He only works on Toyota/Lexus/Nissan/Honda).

 

[Julian Stead]

@2001LC @Julian Stead

Any other tricks/ideas to verify if it is HG or a possible valve issue?

Kind of annoying now that I think about it -- this guy takes my money but doesn't give me the exact issue... I'm still not 100% certain its the HG. Could valves go bad on 2 cylinders at the same time? Wouldn't compression be @ 0psi with bad valves?

The fact that both cylinders have the same low psi makes me think they are connected via breached HG!

Still haven't found a very good writeup... I guess its just like any other HG job though... would be nice to see some problem areas though ahead of time!

A cylinder leakage test would be the next step after a compression test, you have to know what your doing to use this bit of kit as you can diagnose wrong if you don't know what the valves are doing, ideally you would remove the Cam to be 100% but that is overkill, but I would remove the valve cover to be able to see what is going on. For example, if the air leaks into the adjacent cylinder and the exhaust valve is open then you would have leakage at the exhaust even if there is nothing wrong with the valve itself.

A bad timing belt install could damage multiple valves.

Most people would remove the Cylinder head for inspection but I like to do the leakage test.

 

[DirtDawg]

Taking a step back from starting to tear things apart... Have you ruled out a fuel issue? Fuel pressure regulator? Swapped injectors yet? I would eliminate all electrical and fuel variables before looking at HG and valve issues, as mentioned before, these are exceptionally durable engines.

 

[Julian Stead]

I have got to agree that they are durable, but without knowing the history it is hard to tell if the PO had a problem that caused this. We know it has had a timing belt, I worked with a tech that I nicknamed The Dentist as he was always a few teeth out after he done a timing belt, so some people are a disaster waiting to happen. Also has the thermostat or heater tee's gone bad at some point, was it driven without coolant and just water for a long time.

I am sure a compression tester is a cheap tool of EBay, worth a recheck. It is easier to check compression than it is to chase your tail in the hope it is something else at the moment. If the engine is good and compression Test is ok then you will have the confidence to move on in another direction.

 

[DirtDawg]

I have got to agree that they are durable, but without knowing the history it is hard to tell if the PO had a problem that caused this. We know it has had a timing belt, I worked with a tech that I nicknamed The Dentist as he was always a few teeth out after he done a timing belt, so some people are a disaster waiting to happen. Also has the thermostat or heater tee's gone bad at some point, was it driven without coolant and just water for a long time.

I am sure a compression tester is a cheap tool of EBay, worth a recheck. It is easier to check compression than it is to chase your tail in the hope it is something else at the moment. If the engine is good and compression Test is ok then you will have the confidence to move on in another direction.

I agree. I feel like he would be seeing other issues as well though. Hopefully we can help the OP fix this issue.

 

[bajaphile]

A few comments.

1) Fuel - I have not checked this, but I really don't think it is my issue. I've had clogged filters and faulty fuel pumps in the past, and this is definitely different. The truck actually drives great aside from having a rough idle. In fact going 80-90 on the freeway going uphill, it pulls excellent (Remember, this is a 4Runner not a LC)

2) Timing belt replacement - Very possible the mechanic who did the belt replacement F'ed up first and allowed the valves to hit the top of the pistons... however it was done about a year ago and only now started having a misfire and throwing codes. Also to reiterate, I did check and ensure that the timing marks were dead on.

3) Doing a wet compression test. Just gotta do it again. I have pretty good confidence the mechanic who did the test knew what he was doing.

Assuming the compression test comes out the same... I can then start playing around with the leak down tester. I'd pull the valve cover, and watch the valves move as someone else turns the crank... ensure cylinder is at TDC and pressurize it, then listen to hear where the air is escaping to. I believe it is not an electrical issue and indeed either a HG or damaged valves on both cylinders (doubtful).

It is a little bit concerning that after months of Google searches, I've yet to find much in the way of HG failures on the 2uz-fe... a motor used in so many vehicles. This would be my luck though. I always seem to pick the lemons!

 

[Julian Stead]

A wet compression test is used to help diagnose piston ring issues, I have never heard of it to be done as a normal test. If the figures increase with oil then you look at the piston rings, that is what I was taught. That is a bigger issue than just a HG or valve train issue though, but it is possible if it has overheated in the past.

If the valves where slightly bent then that will cause them to get hotter and degrade in time, you don't normally get running issues until the compression degrades to below 100 psi, so when they degrade below this number over time is when your issues begin.

With the risk of a large repair bill then maybe you need to find a tech that is able to do a comprehensive diagnoses. Explain your issue and what has been found and explain you would like a reason to go with the explanation already given. So someone with a cylinder leakage tester, a camera to go into the combustion chamber, and someone generally with a lot more technical knowledge.

I am not sure what you wanted from your mechanic, but just giving you the compression readings and then leaving it to you to decipher them is a bit lame in my opinion, think if a doctor acted in this way. Part of the diagnoses is to give you a reason that they are accountable for.

I used to do a compression test cold and hot at times.

The symptoms and results you have are the classic signs of a HG issue, I like to keep a open mind until I get hard facts to back it up. If it was in the workshop I would carry out more tests, but if it was at home then I probably would of had the cylinder head off by now and taken it to a engineering shop to be checked and then rely on visual inspection of the HG.

A HG job isn't the worst and most expensive job to do so don't get to worried, plus you are only going to be doing one engine bank, by the time you get the timing belt off and the inlet manifold then you are almost there. Hope it doesn't come to this but I would try and get as much information as you can, as in FSM and check you have tools in preperation, or even if you have a place to carry out this type of work.

 

[Julian Stead]

Ps, another issue could be the cylinders hydro locked and bent the con rods, we used to have this on a particular car model that had a poor intake design and was then later modified. It is rare but again something to look out for if nothing else jumps out at you, just check the piston heights at TDC if the cylinder head is taken off.

 

[bajaphile]

Well "luckily" this would be my 5th head gasket repair I've done, so I'm not necessarily scared, just talking this through with you guys as you are more knowledgeable of the 2uz-fe. I honestly thought this was something electrical in nature, and that maybe be a tribal knowledge type repair... For instance... "Oh, the wiring harness loom runs by a sharp bend and check there for a sheared & grounded wire" I donno... (80 series problem for instance).

After reading so many posts, and posts within this thread, I was even further convinced it wasn't a HG issue, and why I brought it to a mechanic in the first place. Not joking, that was the first time I've taken a car to a mechanic for diagnosis. I've done compression tests on probably 50 engines in my life and could have done that obviously, but I thought it was more than that. Only reason I didn't do it myself was that I can't find my nice gauge, and probably was lended out and never returned. I've been researching a new gauge since the beginning of this problem hah.

 

[Julian Stead]

Yeah, it would seem to be a rare problem if it does prove to be a HG. Almost unheard of in a 2uz and also going bad between two cylinders is something you don't come across a lot.

 

[2001LC]

Well, I called a local mechanic who've I known since I was a kid and my dad uses from time to time... He said he'd do a full diagnostics for me for $120... So rather than buying a compression kit, fuel pressure kit and leak down kit, I just had him go for it.

Result: Probable head gasket failure at 3 & 5. Compression on 3 & 5 are at 90 psi, the rest are at ~170 psi. He mentioned that it could potentially be burnt valves at both cylinders, but I couldn't imagine that being the case. The head gasket failure would mean that it was between cylinders and not involving a water jacket.

Looks like I'll be tearing down the motor soon. Any good HG writeups for tips and tricks on the 2UZ-FE would be helpful. Guess I'll start reading through the FSM and tracking down parts.

@2001LC @Julian Stead

Any other tricks/ideas to verify if it is HG or a possible valve issue?

Kind of annoying now that I think about it -- this guy takes my money but doesn't give me the exact issue... I'm still not 100% certain its the HG. Could valves go bad on 2 cylinders at the same time? Wouldn't compression be @ 0psi with bad valves?

The fact that both cylinders have the same low psi makes me think they are connected via breached HG!

Still haven't found a very good writeup... I guess its just like any other HG job though... would be nice to see some problem areas though ahead of time!

A few comments.

1) Fuel - I have not checked this, but I really don't think it is my issue. I've had clogged filters and faulty fuel pumps in the past, and this is definitely different. The truck actually drives great aside from having a rough idle. In fact going 80-90 on the freeway going uphill, it pulls excellent (Remember, this is a 4Runner not a LC)

2) Timing belt replacement - Very possible the mechanic who did the belt replacement F'ed up first and allowed the valves to hit the top of the pistons... however it was done about a year ago and only now started having a misfire and throwing codes. Also to reiterate, I did check and ensure that the timing marks were dead on.

3) Doing a wet compression test. Just gotta do it again. I have pretty good confidence the mechanic who did the test knew what he was doing.

Assuming the compression test comes out the same... I can then start playing around with the leak down tester. I'd pull the valve cover, and watch the valves move as someone else turns the crank... ensure cylinder is at TDC and pressurize it, then listen to hear where the air is escaping to. I believe it is not an electrical issue and indeed either a HG or damaged valves on both cylinders (doubtful).

It is a little bit concerning that after months of Google searches, I've yet to find much in the way of HG failures on the 2uz-fe... a motor used in so many vehicles. This would be my luck though. I always seem to pick the lemons!

A wet compression test is used to help diagnose piston ring issues, I have never heard of it to be done as a normal test. If the figures increase with oil then you look at the piston rings, that is what I was taught. That is a bigger issue than just a HG or valve train issue though, but it is possible if it has overheated in the past.

If the valves where slightly bent then that will cause them to get hotter and degrade in time, you don't normally get running issues until the compression degrades to below 100 psi, so when they degrade below this number over time is when your issues begin.

With the risk of a large repair bill then maybe you need to find a tech that is able to do a comprehensive diagnoses. Explain your issue and what has been found and explain you would like a reason to go with the explanation already given. So someone with a cylinder leakage tester, a camera to go into the combustion chamber, and someone generally with a lot more technical knowledge.

I am not sure what you wanted from your mechanic, but just giving you the compression readings and then leaving it to you to decipher them is a bit lame in my opinion, think if a doctor acted in this way. Part of the diagnoses is to give you a reason that they are accountable for.

I used to do a compression test cold and hot at times.

The symptoms and results you have are the classic signs of a HG issue, I like to keep a open mind until I get hard facts to back it up. If it was in the workshop I would carry out more tests, but if it was at home then I probably would of had the cylinder head off by now and taken it to a engineering shop to be checked and then rely on visual inspection of the HG.

A HG job isn't the worst and most expensive job to do so don't get to worried, plus you are only going to be doing one engine bank, by the time you get the timing belt off and the inlet manifold then you are almost there. Hope it doesn't come to this but I would try and get as much information as you can, as in FSM and check you have tools in preperation, or even if you have a place to carry out this type of work.

A wet test (put some oil in cylinders 3 then 5) as @Julian Stead said is next steep. If compression goes up it's rings. We see leaky fuel injector, which over time, are hard even on the supper tough 2UZ-fe lower end by washing down cylinder wall oil. The sign of this would have been hard starts. Which would have been going on for a long time to damage the rings (clues). I'd assume the mechanic did wet test and got no effect, if he said probable HG.

Next test would be for combustion gas in coolant system. Did your guy do this? If HG leaking between 3 & 5, it's possible it's into coolant system. There is a test which uses color dye. But I would look for low coolant level and water in oil (milkshake). You can also drain coolant and try this as seen in video, combustion gas blowing out coolant line:

Milkshake:

If valves are burnt, which we've seen pictures of on mud, a camera would reveal in short order. I've not look for, but bet there are some inexpensive HD ones that connect to a smartphone. Seem unlikely two cylinders right next to each other get burnt valve(s) and both at 80psi.


I look for cause for issues. I'll be pulling an engine soon and replacing with this engine I picked up (had delivered to my door). I 'll tear it down some day and rebuild. I'll be looking for clues of why. Yes heater Tee blew, but I'm not convinced, yet, it blew just from age. I suspect improper procedure used during flush done by Dealer at different times. The most common is not burping the coolant system. The FSM has a procedure squeeze upper radiator hose that many use, I have not seen work. System always needs more coolant after cool down for 8 hours. Running low on coolant and we overheat, with false reading on gauge that we're ok temp wise. This has some bad effects, head wrap being one. Sign of long term running hot may be found in engine compartment in color changes of hoses and metals.

Transmission came with this 08 2UZ-fe VVti from a 4runner. Sorry reflection of engine was all I found on hand for a picture to post.

I've looked for Head rebuild job all over the net. They don't happen often enough with 2UZ-fe, as most just swap in a engine, which is often cheaper and faster.