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Thread: Missing a cylinder - please help me figure why Reply to Thread
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  Topic Review (Newest First)
Yesterday 11:36 PM
trevor It is so easy to pull the motor on these cars (couple hours of work), I always pull it out and put the motor on a stand. Some much easier to work on.
Yesterday 10:54 PM
Danish Thank you for the input!

I am slowly getting used to the idea of pulling the engine - especially since it seems as a minimum I have to pull the one head (the damaged valve is hard to push down, so it is probably bent). Also still no diagnosis for #8, so that will be a lot easier to do on the engine stand if pulling the cam shaft is the way to do that.


So far the only bit that is unaccounted for is the pin that goes through the roller bearing and the broken part of the rocker - so hoping for finding that in the oil pan.
Yesterday 06:25 PM
Keysergogo I think I see the roller tip wedged above the head bolt, so thats one part accounted for. Sorry for your troubles, luckily the nice driving weather is coming to an end, so it can be a long winter project instead of a rush job. Good luck in the tear down and keep us posted.
Yesterday 05:16 PM
Big Blocker
Cam Bad

I totally agree with Krusty and Norn B on their statements: #4 & #8 do share a common [last] section on the cam shaft and their close proximity could, very possibly, effect one another.

A total tear down is absolutely a given at this point. Broken parts get ground up and distributed to every place in an engine - causing failure to rod and main bearings - which in turn will wipe out a crank or rod(s).

At least pull the pan and pull the rod and main caps to check bearing condition. Flushing out all the oil passages is not a fun process with the engine assembled. Hence, the teardown.

Sorry to hear, and see your problems . . .

Doc
Yesterday 03:54 PM
Norm B That rocker damage most likely will have caused damage to the valve guide and other components in that area. The valve, the spring retainers and cap will have to be inspected and replaced as necessary. I hate to say it but, a complete tear down might be in order. At the very least that head should come off and be checked, the oil pan removed and the oil pump replaced. Those parts went somewhere.


Norm
Yesterday 11:13 AM
trevor That rocker damage may have caused the #8 problem with the possible cam wipe out due to the debris running through the bearings.

Are you sure 1.7 ratio rockers are ok with your cam. You may have binding and this was the result.
Yesterday 10:35 AM
KRUSTY990 That's ugly. #4 & #8 both share the same cam section between the rear cam bearings. My $$ is still on a broken cam.

krusty
Yesterday 03:59 AM
Danish
Quote:
Originally Posted by KRUSTY990 View Post
Any updates?

Krusty
Yes, good timing! I took half a day off from work today to get back in the garage and get this sorted out. I was going to do a full 720 degree timing check to see that all valves were doing what they were supposed do. Took the passenger side valve cover off and this stared me right in the face...


Now I don't know what to believe any longer. I guess Trevor was right when he predicted there is likely more than one thing wrong - unless of cause there is way that a bad #4 intake rocker can affect #8 also.
11-09-2019 10:47 AM
KRUSTY990
#8

Any updates?

Krusty
10-25-2019 01:43 PM
railroad
Quote:
Originally Posted by Danish View Post
I'm working on driver's side bank all the way in the back.
Your are RIGHT. Excuse my mistake.
Do not know what I can blame it on, but woke up this morning and realized it.
10-25-2019 11:53 AM
Danish
Quote:
Originally Posted by railroad View Post
Not that it changes anything, unless you are running your plug wires using that info, but I do not think that is #8.

I'm working on driver's side bank all the way in the back.
10-25-2019 11:50 AM
KRUSTY990
#8

I am with BB. All looks well, BUT I would still manually rotate it through a full 720 deg cycle and check for proper valve timing in relation to crank angle.

Krusty
10-25-2019 04:24 AM
Big Blocker
cylinder missing

After watching the video provided, doesn't look as if it's a "mechanical" issue that is kicking you to the ground, so to speak. Valve train seems to be working fine . . .

Doc
10-25-2019 02:55 AM
railroad Not that it changes anything, unless you are running your plug wires using that info, but I do not think that is #8.
10-25-2019 02:34 AM
Danish It looks like the intake gasket is intact:


Exhaust lifter seems fine also. The intake lifter did not want to come out. Guess there is not enough clearence on the AFR heads without grinding material away.


Is there anything else I can/should check while I am in here?
10-25-2019 02:29 AM
Danish Here is a video of the valves with the valve cover off. Number 8 is to the far right.
https://1drv.ms/v/s!AoFLJPBnL-megP5O1F8SZdsxZD9XUw
10-25-2019 02:19 AM
Danish
Quote:
Originally Posted by Norm B View Post
I, for one, will be really interested in what you find when you take the lower intake off. Remember to drain some coolant first. That's one of those don't ask me how I know things!

Norm
Right - life is a great teacher!
10-24-2019 10:27 PM
Norm B I, for one, will be really interested in what you find when you take the lower intake off. Remember to drain some coolant first. That's one of those don't ask me how I know things!

Norm
10-24-2019 03:46 PM
Danish Thank you for the suggestions - Very much appreciated!
I have planned to take the afternoon off from work today, so I can work a bit more on it.
Since I have a different intake I want to put on it anyway, I will remove the lower intake and try to see if we can eliminate the lifters and intake gaskets as possible causes.
If no luck on that I will move on to the suggested ECU/wiring.
10-24-2019 05:13 AM
Big Blocker
Bad EEC

The injectors are fired by a grounding Triac in the EEC. IF that Triac is bad, injector won't fire, plain and simple. Swapping injectors doesn't test the EEC, or for that matter, the salt-n-pepper connectors if they are still in the circuit.

The injector can be tested out of the car by connecting 12V to it and then grounding it, IF it "clicks", it's probable good. That takes us back to the EEC and those Triacs that perform the grounding. Has the EEC been opened up and checked? Burnt traces, burnt components . . .

Has the EEC been swapped out with a known good working unit?

Also, has the injector been removed and the fuel rail checked for any obstructions at the #8 port?

Maybe the rail is plugged up and there is fuel at the injector and the injector is firing but the fuel can't get there dues to some sort of debris in the line. Swapping injector wouldn't matter if the line is plugged.

Just trying to help . . .

Doc
10-23-2019 10:05 PM
Brewha This is like a whodunit mystery. I’m betting on a fuel injection issue. You have spark and you passed a compression check. All that is left is fuel to provide the bang and heat.
You can have the following issues
1. You can have the ECM call for the fuel, power delivered to the injector, and the injector not fire.
2. You can have the ECM call for fuel ,power is delivered to the injector and the injector does not spray enough fuel .
3. You can have the ECM call for fuel, power is NOT delivered to the injector, but the injector is capable of firing if it received power.
4. The ECM does not call for the fuel for that cylinder.

Sounds like you moved injectors around so I would check the power going to #8 injector to see if it’s there power and if it has enough to fully engage the injector.

If the power is good then it may be time for a new or reprogrammed ECM.
Good luck, I can’t wait to see what caused this.
10-22-2019 12:05 AM
johnnybgoode Any chance the high revs could have sucked out the intake gasket? Any coolant in the oil and/or can you do a coolant system pressure check to see if its leaking into the motor?

Weird problem. Best of luck with it. Scott
10-21-2019 03:17 PM
Norm B A couple of observations from your pictures. You have full motion of both valves. This indicates your cam, lifters and pushrods appear to be fine. Since you have the rocker off, pull the pushrods and roll them on a flat surface. Any bend will become readily apparent. Valves sticking open can cause a miss but on our engines it would result in valve damage. You don’t have that because your compression and leak down tests were good.

I would keep chasing fuel and ignition problems and since you’re this far apart change the intake manifold and gaskets.

Good Luck

Norm
10-21-2019 06:01 AM
Big Blocker
Running with VC's off

FWIW, small clip on wires with a rubber tip are available that clip to the rockers and plug the oil hole . . . just so you can idle the engine with the valve covers off.

Doc
10-20-2019 01:25 AM
Keysergogo Also, the rocker laying on its side - it looks like some part of the fulcrum shaft or bearing is protruding underneath the snap ring - at about 2 o’clock in the picture.
10-20-2019 12:22 AM
Gregg Wade Is the tip roller pin coming out of that rocker arm on the the right?
10-19-2019 05:08 PM
Irwin Ayes Danish, just a thought. The underside of the pictured rocker appears to have been binding in several places. Most rockers, I've ever seen, appear to be smoother/ better finished, than yours appears. Just my 2 cents worth, Irwin.
10-19-2019 03:03 PM
railroad If you are going to start it up without the valve cover, I have had good luck with a couple of heavy rags across the top of the valve train, less the ones I want to see.

Depending on the spray, you should have a couple of minutes before it gets messy. I put the edges of the rags inside the valve cover lip.
10-19-2019 03:58 AM
Danish Update: Pulled the upper intake and valve cover off to give the rockers, pushrods etc a better look on #8. I have attached some pictures, and all seems to look good. It looks like the valves timing are about right relative to the piston position. I was able to put the endoscope into the cylinder, and it does not look like the piston has been in contact with the valves – at least judging on looking at the top of the piston.

With both valves closed there is no play in the rocker. I am able to turn the pushrod by hand even if it is pretty tight.

So if it was collapsed lifters would the internal spring in the lifter be able to open the valve when the engine is turned by hand and then “collapse” or keep the valves from opening at all when the engine is running?

What is the best way to diagnose that? I am almost tempted to run the engine without the valve cover and see what the valve do. It will probably be an oily mess but what else to do?

The spec for the valve springs are: 150# seat, 400# @ 0.66" max lift. I replaced the lifters two years ago with original Motorcraft when I put the AFR heads on.
10-18-2019 04:54 PM
Tom Sharpe I can't wait to hear the solution. If the compression, leak down, and valve motion is good, it's mechanically sound, no need to pull the heads. PS, the leak down test will show bubbles in the radiator if you have a bad head gasket. It will also whistle in the intake or exhaust with a bent/burnt valve. Loose rocker indicates bad cam or rocker/stud or pushrod. You can see broken springs, etc.
Swapping the injectors and injector wires are great tests to locate a bad injector or wire or ECU issue. I would have bet on the plug wires.
I think it might be a bad intake gasket. Is the plug wet with gasoline or antifreeze or both? That could cause the misfire. Maybe your scope can see something at the head/intake location.
Closing the throttle at high RPM spikes the vacuum in the intake/cylinders. Race motors occasionally break rods - they are pulled apart as the crank tries to yank the piston away from TDC at high RPM with high vacuum readings, also hard on bottom rod bearings. You may have pulled the intake gasket out of position.
PLEASE keep us posted.
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