SOLVED! Post 2853 Leaking Injectors, Dealer Techs Rock! Extended Cranking after Engine Swap 3.4L 5vz

Now I want ribs!

 

Thanks for the input guys!

Seems like the consensus is that while it's not right to have compression results like this with a re manufactured engine that was properly rebuilt, it is something that should not be considered a "throw in the towel over it" type thing. That it's OK to drive it like this, it's just not ideal in terms of performance and is fine to wait on addressing, if ever. So I am feeling much better about this.

Thanks everyone!

 

Seriously man! I am starving for bbq now! Thanks a lot TenBeers

JK, thanks for the tip buddy! We've never been there, but I've heard that place is awesome. Think I saw them on the Food Channel once, and they were getting a great review. If we go, I will say hi to Rodney for you!

PS - Eric dropped off the parts and got to chat with Noahpete and Jayman......let me just say I am definitely feeling better about all of it after hearing about that - those guys are on top of things big time!! Lots of testing and critical thinking going on to solve this mystery problem! So happy about that!!!

 

I used to work in high-tech with Rodney back in the 90's (robots and cool stuff like that), and Rodney decided he would rather cook. He threw in the towel, went to culinary school, and then toured the nation sampling BBQ from around the country. He started in downtown Portland selling BBQ from a cart. He's been written up multiple times and is supposed to have the best BBQ in the northwest. Gotta respect a guy that follows his dreams. I get some sauce brought in occasionally, but sadly I haven't been back to Portland in many years.

 

Tuesday April 21st 2015

Arrived to work and started truck after it was sitting all night. Intake temp (underhood temp) 71 deg, coolant temp 76 deg. Fuel pressure had completely bled off to 0psi. Truck still cranked and started normally under these conditions

Drove around the block a few times to get up to temp, coolant temp was 195 deg and intake temp was 91 deg when parked and ignition turned off

http://www.tacomaworld.com/forum/attachment.php?attachmentid=323788&d=1429662533

After hot soak (I used the timer on my phone for 30 mins) the truck has had the worst start that I have witnessed. The intake temp after sitting had risen to 101 deg and the coolant temp was 166 deg. Note that fuel pressure is at 48 psi when the engine is having trouble starting. I'm concerned that the fuel pressure problem may not be a problem but I haven't come to a decision I'm going to keep testing and not jump to conclusions

https://www.youtube.com/watch?v=27i8IQb2l5U&feature=youtu.be

Inspected cam timing/timing belt timing/valve timing and found that crank and cams all lined up correctly

Crank
http://www.tacomaworld.com/forum/attachment.php?attachmentid=323789&stc=1&d=1429665883

Driver side cam
http://www.tacomaworld.com/forum/attachment.php?attachmentid=323790&stc=1&d=1429665883

Passenger side cam
http://www.tacomaworld.com/forum/attachment.php?attachmentid=323791&stc=1&d=1429665883

Here is the oscilloscope reading of cam and crank sensors while running. The red trace is the crankshaft position sensor (34 teeth) and the blue trace is the camshaft position sensor (1 tooth)

http://www.tacomaworld.com/forum/attachment.php?attachmentid=323810&stc=1&d=1429666086

 

All of the sensors look good to me. Don't see an abnormal signal from either.

 

koditten: I'm not noticing raw fuel smell from exhaust during hot start (from in the truck with the windows open) but I haven't ran around to the back

Mod: I agree with inspecting the valve clearance before condemning any valves. This is coming up on the agenda

Dirty Pool: sweet fuel pump pics I have not seen one disassembled before. The fuel pressure gauge set up I'm using has a cutoff valve that will close everything on the engine side (injectors, return line, everything). When the valve is closed the pressure gauge only goes from fuel pump to fuel filter to pressure gauge. So I plan to test the pressure for the fuel pump only

TenBeers: you noted suspecting the injectors leaking down and I agree that is a possibility. the set of injectors I have must have come out of a newer 5vz because they look different in shape and size. I didn't know there were differences. I do intend to see if the whole set will fit on there b/c I have the fuel rail and piping for them.

So... on the agenda are testing fuel pressure for pump only, inspecting valve clearance and swapping (or attempting to swap) fuel injectors

 

I like that agenda...If cam timing is spot on, and the motor should have been run enough for the valves to seat, I wonder if during the poor warm starts if the valves are sticking in the guides? If incorrect valve guide material was used, sticking could occur. I know this is kind of far fetched, but unless the injectors are leaking and flooding the cylinders (except the plugs don't look fouled).

Sticking valves should show up as excessive gap...depending upon what conditions they stick. When the motor runs, is there a miss?



Howard

 

Wow! Again, thank you so much for putting such awesome efforts into solving our truck's issue!!! So thankful!!

That seems strange that the fuel pressure went to ZERO, yet the truck still started normally. Also seems bizarre that the pressure was so nice and high at 48 during that horrible start! Weird.

Yep, you definitely caught one of the worse starts there. I'm glad you got to witness one first hand!!

So eager to see what your future test results show, this has already been extremely informative and you've only had the truck for 2 days!! Thank you so much!

 

OK, been thinking about the leaky injector possibility, coupled with the fuel pressure dropping to 0 yet starting normally in the morning. Here goes our wacky theory of the day (I'm blaming it on Eric if it's wrong, but it was ALL my idea if it's brilliant, OK? Don't tell anyone I said that though! )

So if injector(s) are leaking overnight, would enough fuel possibly drip into the cylinders to allow it to start, even with 0 fuel pressure? And if so, wouldn't the plugs have to show SOME wetness first thing in the AM, before it's started?

Reminder - Eric's idea if wrong; my idea if right

 

It's actually a little different than that.

For the engine to start, it needs a proper fuel/air mixture as well as a spark. A "flooded" engine has too much fuel in the mixture. In the olden days, you would put the pedal to the floor to open the butterfly and allow more air in to get the mixture right. You still might have to crank for a bit to clear it out. Alternatively, you could just wait a while and let the fuel evaporate.

The problem with a leaky injector is that it dumps fuel into the intake until the fuel pressure drops off, creating a "flooded" condition for a period of time. A warm engine will not like this. A cold engine has probably had enough time for that fuel to evaporate. Keep in mind that the leaky injector will not leak fuel into the intake all night -- only until the pressure has dropped off.

Fuel pressure should naturally bleed off over time, but it should bleed back into the tank. Fuel pressure will rise back up quickly as soon as the fuel pump is energized. Slightly lower fuel psi while hard starting could be due to more electric energy being diverted to the starter rather than the fuel pump (kinda like seeing your dome light dim a little while starting). Probably not a big deal, but I don't know the specs.

It seems like on your vehicle, it sometimes starts fine when warm, but mostly has trouble. The new guys have noticed 2 different rates of fuel pressure drop. I am wondering if the starting behavior correlates with those 2 different behaviors. That could point to an injector that sometimes leaks and sometimes closes off properly.

Here's the theory:

Normal fuel pressure drop: Normal warm start (injector closed properly)
Accelerated fuel pressure drop: Hard warm start (injector stayed open and created a flooded condition)

 

If flooded, wouldn't the plugs look or smell gas fouled? We are NOT seeing that.

Howard

 

Maybe over time, but there are relatively few miles on these plugs. Most likely it is not consistently running in a rich condition once it gets started, so it may take some time for that to show on the plugs.

It's still just a theory/guess at this point based on the behavior.

 

It would have to be abhorrently rich, constantly, all the time, to black soot them enough to see it well with new plugs. You would smell that for sure and would probably get pulled over for towing a sooty fog bank as you drove,,in Oregon.

Your fuel gauge would be unhappy as well.

 

I still say to bleed the pressure as soon as the engine is turned off. This will prevent fuel from leaking into cylinders from a bad injector. Then wait the whatever time and crank the engine.
Should be pretty easy with all the gear the new mechanics have.

 

I have seen plugs gas foul in very short periods of time...

Howard

 

Kind of off the current topic(s), but FWIW, here's another description of what the engine we received should consist of:

A long block is a short block with cylinder heads, camshafts and oil pump installed. Cylinder head are Toyota castings that are stripped down bare, inspected, and measured for thickness. Heads that pass inspection are surfaced for a true mating surface to match up to the machined surface on the block.
• Cylinder head seats are inspected and replaced as needed
• Toyota valves are measured for trueness and inspected with passing valves given a 3 angle valve grind and lapped into the cylinder head
• New valve guides and seals are installed with all valves vacuum tested to ensure each will hold adequate pressure
• Camshafts are cleaned, measured and inspected with passing camshafts micro-polished smooth
• New cam buckets are installed with shims to obtain proper clearances
• Cylinder heads are installed to the block with new TTY head bolts tightened to factory specifications Toyota OEM head gaskets are the only head gasket we use. A surfaced head, surfaced block, OEM head gasket, and new TTY head bolts torqued to factory specs will guarantee the longest life possible out of your engine. Cutting corners will result in shorter engine life and premature head gasket failure. Toyotas 5VZ-FE 3.4L uses TTY head blots. TTY is Torque-To-Yield, meaning the head bolt stretches and is a onetime use head bolt.
The 5VZ-FE long block comes with a 2 year /24,000 mile warranty included. Engines sold with exchange for your rebuildable core.

EDIT: Oops, it should consist of the above PLUS the "dressed" part of a "dressed long block" meaning it also included timing belt, water pump, etc. Mechanic #2 felt the timing belt and water pump looked new/good....

 

I would like to see the vacuum test report on valve seating...With the leakdown test data presented, the valves are not seating properly...

 

Bingo! Right like what I was expecting!

I think most of us all have commented on suspecting a leaking injector as a culprit. I don't think ANY of us have not mentioned that at least once. We can only rely on what the earlier techs have said that they tested the injectors, and all were fine.

 

Just a thought on the leakdown numbers. I think 30% on an engine that was freshly rebuilt is terrible. I now there are millions of engines running around with way worse numbers, but they sure didn't come that way, but it's terrible for an engine that supposedly just had a three angle valve job. Here is my theory...
Normally during a proper valve job you remove (grind) some material from the valve and cylinder head to create a new sealing surface. This in turn sinks the valve slightly in the head making the stem closer to the rocker (or lifter, or whatever your particular engine design has). To compensate for the added length of the valve stem, some material is removed from the tip of it. If you leave it too long and or don't set the lash properly, the vales will hang open. They will expand and especially hang open after they are heat soaked from sitting in a hot engine for a while after coolant stops running. I'm s really common on small engines like atv's and dirt bikes to have this problem cause a hot start issue. The valve grows in length when it sits and as a result gets further off the seat, causing loss of compression, and hot start issues. Once the engine starts, airflow and coolant start flowing, and the valves shrink down an seal reasonably well.
I'd be curious to see the compression and leakdo n numbers on cyl 6 after its sat hot for 30 min, as well as the valve lash numbers.