Low Vacuum
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Three Wheeling
Joined: Mar 2012
Posts: 59
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Another thing a little strange was 3 thin steel gaskets on each side(front and rear pairs) Never seen this before. Used to have to do tricks to the intake manifold when we milled the heads too far but never on the exhaust side.
Baja
Joined: Mar 2010
Posts: 5,584
Likes: 7
From: Pittsburgh PA suburbs.
ok i started it up today (and it starts great) after a few minutes to warm up there is quite a difference in exhaust manifold temps. Passenger side warmed up first. Center of manifold 200degrees plus ends stayed around 90 degrees. Drivers side sorta the same. Went to 390 at the center stayed around 100 at the front. Coldn't get a good view of the drivers side rear. After warming a little passenger side was similar 390 at the middle 100-110 at the ends. Pulled the plug wire off of number 1 cylinder(driver side front) good spark but no change to engine(cylinder ain't hittin) pulled number 5 (passenger front) good spark cylinder not hittin. Pulled number 6 next to number 5. That cylinder is hitting.
Possible analysis<
ends of exhaust manifolds have rats nest or are clogged, middles are open(doesn't seem likely but it don't look hard to pull the passenger side)
something internally is affecting the outside cylinders different from the inside cylinders. (pull intake plenum and see what's up there. Then valve covers)
it appears that the plenum needs to come off to pull the drivers side valve cover. I'm thinking of pulling passenger side valve cover, it looks easier and seeing if the valve stroke seems uniform. That'd check a worn cam lobe. Next would be passenger exhaust manifold(this seems an unlikely problem.) then plenum to check out for clogged intake ports. (again unlikely as the compression was too uniform)
the plugs missfiring could be carbon fouled again but the engine just doesn't feel like its missing. Wish i had an old sun scope to put it on
any other ideas?
Possible analysis<
ends of exhaust manifolds have rats nest or are clogged, middles are open(doesn't seem likely but it don't look hard to pull the passenger side)
something internally is affecting the outside cylinders different from the inside cylinders. (pull intake plenum and see what's up there. Then valve covers)
it appears that the plenum needs to come off to pull the drivers side valve cover. I'm thinking of pulling passenger side valve cover, it looks easier and seeing if the valve stroke seems uniform. That'd check a worn cam lobe. Next would be passenger exhaust manifold(this seems an unlikely problem.) then plenum to check out for clogged intake ports. (again unlikely as the compression was too uniform)
the plugs missfiring could be carbon fouled again but the engine just doesn't feel like its missing. Wish i had an old sun scope to put it on
any other ideas?
idea: You got the plug wires and the coil pack plug numbers crossed up! Check your plug wires.
Front drivers side is plug 1
front passengers side is not plug5, it is plug 2.
Driver's side is 1-3-5-7 front to rear.
Passenger's side is 2-4-6-8 front to rear.
At least that is how mine is. The numbers are impression stamped on the frame of the coil pack, i have to stand on something elevated to see them.
Thread Starter
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Three Wheeling
Joined: Mar 2012
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could be I'm wrong on the cylinder numbers, that's why I also described them geographically. Pulled the passenger rocker cover today. All the valves visually appear to be normal. I guess I'll go ahead and throw a set of plugs and wires on next. I replaced one plug passenger front with no change I don't suspect plugs but I guess it could be wires. Just tryin to do easy stuff before I go ahead and pull the heads. I'd like to diagnose the problem rather than throwin parts at it.
Rock Crawling
Joined: Feb 2012
Posts: 267
Likes: 4
From: Southwest CT
You stated you pulled #6 next to #5. That would certainly cause a problem. The rover uses lost spark, the coils are used for 2 cylinders and fire one 180 degrees out.
Listen to Danny and check your firing order before going further.
Listen to Danny and check your firing order before going further.
Baja
Joined: Mar 2010
Posts: 5,584
Likes: 7
From: Pittsburgh PA suburbs.
At least make sure that the physical plug is connected to the correct coil terminal going by the designations that are stamped into the coil mounting frame.
Odd numbers on driver side front to back and even numbers on pax side again ascending order front to back.
I recall some American v8 are numbered 1 to 4 on ds and 5-8 on ps.
But the LR 4.0 is as stated above.
I saw the firing order listed in other places but that is automatically controlled and correct.
But as we all know if you got any wires connected to wrong spot, then at least two spark plugs are not going to fire correctly, maybe more.
It may just be you described it based on a different arrangement, but it is worth verifying.
I remember thinking that odds on one side and even on the other was different than what I was acustomed to, but each mfg can have their own numbering system.
I do like the fact that the bracket is steel stamped. That is one good thing they did.
I liked my old Datsun 280 -straight 6 direct fuel injection and I never had a problem with it until 280,000 miles.
The Volvo 240 that replaced it was a 164 cubic inch in line 4 direct fuel injected and it was even faster than he 280 was.
Odd numbers on driver side front to back and even numbers on pax side again ascending order front to back.
I recall some American v8 are numbered 1 to 4 on ds and 5-8 on ps.
But the LR 4.0 is as stated above.
I saw the firing order listed in other places but that is automatically controlled and correct.
But as we all know if you got any wires connected to wrong spot, then at least two spark plugs are not going to fire correctly, maybe more.
It may just be you described it based on a different arrangement, but it is worth verifying.
I remember thinking that odds on one side and even on the other was different than what I was acustomed to, but each mfg can have their own numbering system.
I do like the fact that the bracket is steel stamped. That is one good thing they did.
I liked my old Datsun 280 -straight 6 direct fuel injection and I never had a problem with it until 280,000 miles.
The Volvo 240 that replaced it was a 164 cubic inch in line 4 direct fuel injected and it was even faster than he 280 was.
Super Moderator
Joined: Jan 2011
Posts: 16,322
Likes: 88
From: Savannah Georgia
I was able to get 10 inch of vac at idle, rough, with two center plug wires on passenger side swapped. With a single wire off, about 13 inch.
And on my D1 those thin metal plates exist on the exhaust manifold to head connections.
I think Danny used his Jedi powers and saw this one.
And on my D1 those thin metal plates exist on the exhaust manifold to head connections.
I think Danny used his Jedi powers and saw this one.
Baja
Joined: Mar 2010
Posts: 5,584
Likes: 7
From: Pittsburgh PA suburbs.
When I read his details and said wiat a minute, the front pax is 2 not 5.
I would be concerned about running it with any spark plug wires crossed.
I( remember my old 283 jumped timing in traffic, flames shot back up out of the carb but it was still running somehow. I was in bumper to bumper traffic on I75 South out of Atlanta in Rush Hour.
I ripped my shirt off, raised the hood (motor between front seats) beat the flames out and manged to limp another 30 miles home with it like that.
I gave the motor to a friend. He rebuilt it for a 1967 Camaro he was rebuilding.
When he took it apart, he told me the fiber timing gear had three teeth left intact and the shredded fibers were everywhere.
I did give it to him for hauling it out of my mother's garage as it had sat there in the corner for years. He was thrilled to get a Factory PowerPack Double Humper 283.
He told me those were rare factory hotrod motors. It was in a $700 van I bought from a neighbor.
I would be concerned about running it with any spark plug wires crossed.
I( remember my old 283 jumped timing in traffic, flames shot back up out of the carb but it was still running somehow. I was in bumper to bumper traffic on I75 South out of Atlanta in Rush Hour.
I ripped my shirt off, raised the hood (motor between front seats) beat the flames out and manged to limp another 30 miles home with it like that.
I gave the motor to a friend. He rebuilt it for a 1967 Camaro he was rebuilding.
When he took it apart, he told me the fiber timing gear had three teeth left intact and the shredded fibers were everywhere.
I did give it to him for hauling it out of my mother's garage as it had sat there in the corner for years. He was thrilled to get a Factory PowerPack Double Humper 283.
He told me those were rare factory hotrod motors. It was in a $700 van I bought from a neighbor.
Baja
Joined: Mar 2010
Posts: 5,584
Likes: 7
From: Pittsburgh PA suburbs.
We did it
Savannah,
I recognized from his description of the plug locations that it was not correct for the LR 4.0 from my own experiences. Specifically when I had to remove the coil bracket to replace front O2 sensors.
I would like to go a step further and possibly even relocate the coil mounting bracket to a better location. All of my experience on the Cruise Missile was predicated upon process/product improvements.
You took it to the next level of verification by replicating the condition and verifying with real-life data. (Emperical data It hink it is called).
Now it is up to the OP to see if we are indeed correct and follow up with the findings. That is how this process should work.
Not wild *** guesses, hypothesis, opinions or feelings.
Of course some good campfire stories help.
Do I deserve to be a Branch Manager in your famous shade tree? I will only accept it as an Honorary Position without taxable compensation.
Under the table wagers however are fair game. Kickbacks accepted as well as gifts from any appreciative individuals.
I recognized from his description of the plug locations that it was not correct for the LR 4.0 from my own experiences. Specifically when I had to remove the coil bracket to replace front O2 sensors.
I would like to go a step further and possibly even relocate the coil mounting bracket to a better location. All of my experience on the Cruise Missile was predicated upon process/product improvements.
You took it to the next level of verification by replicating the condition and verifying with real-life data. (Emperical data It hink it is called).
Now it is up to the OP to see if we are indeed correct and follow up with the findings. That is how this process should work.
Not wild *** guesses, hypothesis, opinions or feelings.
Of course some good campfire stories help.
Do I deserve to be a Branch Manager in your famous shade tree? I will only accept it as an Honorary Position without taxable compensation.
Under the table wagers however are fair game. Kickbacks accepted as well as gifts from any appreciative individuals.
Last edited by Danny Lee 97 Disco; Apr 7, 2012 at 03:52 PM.
Thread Starter
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Three Wheeling
Joined: Mar 2012
Posts: 59
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Checked plug wiring setup today. All appears to be in order. Cylinders are numbered as they attach to the crankshaft from front to rear, that makes driver front 1 passenger front 2 and so on. THats how they were attached to the coil. All new plugs. Started right up, 13 inches of vacuum for about 15 seconds then to 11. Still won't rev. Fuel pump pressure is 38 still a little high. Injectors next?