Missfire on 3vze #4

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Bluejerseydevil

Joined
Jan 3, 2011
Threads
3
Messages
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Ok I'm about to drive this thing in to traffic and jump out!!! Its been two months i had a valve job t belt and it's been fine till five days ago my 88 3vze Has a miss on #4 ,new plugs,wires, cap, rotor,injectors, im already about 1300 just in parts this week in the hole and i checked every vacuum line. I want to hear what you might think it is? I'm guessing a stuck valve. I did seafoam it a few months back and it ran great! But out of the blue this started.
Tuesday I'm calling Doc's shop in Jackson nj and making a appointment ASAP before I loose it.
 
How does the exhaust smell? Is the catalytic converter running hot? Is the check engine light on? If so, what are the codes?

There are some wires for the injectors that have splices in them. The splices like to die, and yours is old enough for that. If the one for the #4 injector failed then that cylinder wouldn't fire as it isn't getting any gas.
 
Basics

Why don't you start looking at the basic components before you start loosing your hair about this.check for spark,fuel,compression this 3 basic things is required for combustion and a lot of times the cause is w/in this 3 items if you have low compression get a leak down check to see where is the leakage.check and see if the injector is firing or getting a signal from the ecu,your basic compression should be above 75 psi or else it will not ignite in most cases,swap out wires or check the dist. cap for possible carbon tracking new parts can be bad out of the box.hope this helps in your search.;)
 
I've replaced every Thing it's down to either a bent valve was put back in it when the head was done or a valve spring broke. I bought a used motor to send the heads out. I've had this problem from 06 till now. I could have bought a new truck already.
 
The head design on the 3VZE is lacking as far as adequate cooling goes. Cylinders #4 and #6 are notorious for burnt exhaust valves. I replaced heads twice with rebuilt ones, only to lose compression on those cylinders very quickly again. Do you hear what sounds like an exhaust leak coming from that corner of the engine?

I finally swapped in a 5VZE!
 
A compression check will tell you alot. Ive been on the same path as you, I pulled both heads and regroung/replaced valves honed, new rings, bearings, pistons and still burned a exhaust valve this summer. I was able to re shim it and limp for a while but now I'm ordering brand new heads from a place in california tomorrow. Over 300,000 on the first set of heads, so I hope the new ones last. For those of us that run 3.0s its always a concern. When mine start to miss a bit, I hold a dollar bill in front of the tail pipe at idle. If the bill sucks in and out of the exhaust then its another burned exhaust valve. Ive gotten to know my 3.0 quite well. My mechanic skills have grown alot. :)
 
now what?

Did you even try finding out whats wrong with your rig?:frown:
 
Ok now, I've been a Vw mechanic for 15 years built over 60 air cooled and water motors and am no stranger to total engine rebuilds. I've owned toyotas for a good 10 years and have never ever encountered what I had found.
When I would check the compression it wasn't bad but not great either and knowing that the bottom end was new. I know I could rule out rings. I would check 1 through 6 write it down then I decided to check a few more times and each time got reading that were way off. So I then checked my valves and they checked out ok. Then run it check again and a few were really tight. At first I was like maybe a lifter or two was sticking but nope.
What I found was the shims were tapered causing a tight valve every now and then As the lifter spun.
They basically looked like wedges. Almost as if they were machined that way.
I put good flat shims in it last weekend and I couldn't be happier.
I've never seen any thing like it before I really was beating my self up over this motor. I kept telling my wife " I don't get it!? I know I know what I'm doing!!!"
At least that's what I was telling my self.
 
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