The engine mystery deepens...

Hello all,
I have been trying to work through a problem with my 2000 SR5 4.7. this engine has 260k miles, and until fairly recently ran great. This is a 2UZ-FE Non VVTi

The Issue: According to code reader, misfire 1,3,5,7, and rich on that bank. Run rough at idle and really rough around the 1900-2400rpm range, can smell raw fuel from exhaust when giving it some throttle.

Whats been done so far: 1 new coil pack on cylinder 7. Reman injectors, injector plugs have been noid tested, and all injectors read proper resistance. new plugs gapped correctly. New timing belt and pulleys, triple checked timing marks on crank and cams, it is spot on. I have checked all valve clearances, and they all fall within the middle of their given spec range. It has all new O2 sensors (4 of them). New MAF sensor. New water pump. New starter. All fuses have been checked. Battery ground is also solid.

I am at a loss for what is happening with my engine. With no other codes for any issues, I'm not sure what to do.
I took it to the local toyota dealership for a diagnostic. They claimed the tech whom worked on my truck was certified higher than a master tech.?
I was told i had half compression on cylinder 5 (90psi) and most likely had a burn valve and they recommended replacing my engine with a used unit, due to the cost of a valve or head job.....
I was a loss, when i took it home and found full compression on all cylinders (165-180psi) as well as perfect valve clearances and valves. When confronted the dealership said that they had never seen a tundra with my kind of milage and that my engines parts were close to the end of their life, as well as stating that the low compression they found was most likely due to the cylinder being washed down with fuel. (which if you were some fantastically highly certified tech, you would have been able to discern from all the fuel in the cylinders on that bank!)

So pretty much, no one can figure out what is going on, and the "professionals" made ME feel smart.

Do I have a bad ECU or PCM? Have I possibly sheared the pin on the cam gear? (read about this in another forum post)
I have a job and trip this coming weekend, and hoping to perform a miracle of getting the beast running again!!!
I would gladly reward whom ever can help me figure this out, with a case of your favorite adult beverage! (if thats allowed here)

Thank You

 

Where do the coil packs on that side of the engine get their signal? Is it feasible to swap all the coil packs from one bank to the other to see if the cylinder specific misfire code follow the coil packs? @LOTSOFTOYS is our resident Toyota Technician, I'm sure he's well versed on the 4.7L.

 

I have not done this yet. They are fairly easily swappable, but seeming as how I have not gotten error codes signaling a faulty coil, since replacing the one bad coil on cylinder 7, I figure the rest are good, but this might be worth a try. At this point, I'd try unicorn farts, if that'd fix the problem.

 

Are you sure the timing is dead on the money? 2uz-fe is a interference engine.

 

Ya, my not knowing if on the 4.7L if each cyl. has it's own coil or not. Or if like the engines I've had dealings with, each coil fires two cyl., I'm kind of grasping in the dark. So, just to clarify, with the one coil pack replacement, you're no longer getting ANY codes, but it's still running like rubbish?

 

Have you had the fuel pressure checked? If the pressure regulator is out, it could be dumping excess fuel instead of recycling it back to the tank.

 

Correct, this is why i believe i could have sheared the pin on the cam timing sprocket. All timing marks align, but still runs like the timing is off.

 

Correct. each cylinder has its own coil. No code for faulty pack after replacement, but I am getting misfire codes for all cylinders on bank 1 (1,3,5,7).

 

I believe this was checked by dealership, but not certain on that. If the return/regulator was faulty, wouldn't this affect both sides of the engine? or only the side with the regulator?

 

Okay, that's the rational for asking what signals their firing. Back tracing.

 

Does it in fact misfire on all 4 cylinders? If it does it would barely run if at all... need to verify it is actually misfiring on the scan tool on those cylinders

 

What drives the coil packs and could that be intermittent/failing/poorly grounded/connected resulting in the misfire moving thorough all four cylinders intermittently?

 

IF the vaccuum line to the fuel pressure regulator runs to that side of the intake manifold, it could explain the missfires / rich condition on that bank. A leaking diaphragm in the regulator means fuel enters the manifold via the vaccuum line, in addition to what is injected.

 

Need to first know of it is actively misfiring in all 4 cylinders

 

Not sure if my code reader has that function? So far just the misfire codes. I'll look into the ability of my reader.

 

regulator and vacuum line are on the opposite side of engine from my issues.

 

Again,
I'd like to bring up the sheared cam timing sprocket pin. If this was the case, isn't it feasible for all timing marks to align correctly, but the cam with sheared pin could be rotated slightly?
This issue has occurred to another forum member, his cam was about 25 degrees off, head showed no damage besides the sheared pin, he was able to have a shop remove damaged pin and reassemble engine. it is now running good as new. How common is that!?

 

Yeah, I see that, I dug up a diagram of the 2UZ-FE fuel plumbing and rails. A restriction between the two rails could force the fuel pressure higher on the left bank, otherwise everything is common to both banks. Make sure the crossover tube isn't damaged or kinked if you haven't already. I also wonder if a failed pressure pulsation damper on the back of the left rail would effect that bank more. (Item 23270 in this diagram - don't look at the prices, it's Canadian )

http://www.toyotapartsdirect.ca/a/T...uel-injection-system/220746D-2211-841420.html

Cam timing could be a possibility, but it's not out 25 degrees if you are getting compression numbers like you are. And I'd second Jace's suggestion of looking at live missfire data, something basic code readers won't help you with. A pro-grade scanner or Toyota Techstream would be needed.

Lets go back to the beginning though, how did this issue begin?

 

You could also try loosening the exhaust flange on the left manifold and see how it runs, it might be a plugged / melted Cat.

 

This started back in january, truck started running rough, upon investigation i found a small leak at water pump, and seeming as how all of those components had over 150k miles on them, figured it was time to do some maintenance. I did end up throwing some parts at it that maybe weren't needed right then, but I looked at it as preventative maintenance.

THIS JUST IN!!!!!!!!

so I swapped all the coils from driver side to passenger side and suddenly had a misfire on cylinder 6. All misfires previous to this change were on 1,3,5,7. Performed a couple redundancy test to confirm this. Replaced that coil and the truck is running much better, but trill has a rough patch or misfire in the 2500 rpm range, runs smooth above and below that. Will be performing a leak down test on all cylinders tomorrow to confirm no valve or ring issues.

 

With a better scab tool u can watch live data of what is happening. Sounds like u are headed in the right direction. Alot of times one cylinder will miss but the computer sets codes for multiple...

 

What is the status and fix for your issue! I have done the same fixes as yours and still nothing. Please post of any new findings, Thanks.