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Discussion Starter · #1 ·
Hi everyone. I recently bought a 2004 Discovery with a blown head gasket on Cylinder 4. I tore it down, had the heads milled and pressure checked and replaced the gaskets and bolts. I turned the crank around a few times while I had the heads off to see if any of the cylinder sleeves would move but there was no indication of a compromise there. I was not able to pressure check the block, so that is unknown.

Now that it's back together, I'm not seeing any glaring signs of coolant getting into the combustion (there isn't anything coming out the tailpipe and the reservoir seems to keep full), but I'm getting HORRIBLE performance.

First, it won't accelerate worth a lick, even at full throttle. It's feels really bogged down. There is a fairly rough idle as well.

I removed the SAI system and plugged the holes on the head, so I'm wondering if this has any contribution (it is throwing a code).

Here are the following codes I consistently receive along with multiple cylinder misfire on Cyl 1, 4, 6, and 7:

P0413 (SAI vacuum solenoid valve not connected, open circuit)
P0154 (O2 sensor Bank 2 Sensor 1 no activity detected)
P1319 (knock sensor 1 circuit short to ground)

Also, my Torque app shows there to be an Open Loop Due To System Failure on the Fuel system status.

Thoughts?

Aaron
 

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Hey Aaron
First thing I would look into is the no activity on the O2 sensor. Connector is a bit of a pain to get to but make sure it is clean and tight.
If you had a head gasket go it possibly got contaminated and is now no good.
Could be the cause of some of your misfires.
Another common fault is mixing up the ignition wires at the coil packs. Confirm proper connection and order.
As for checking "slipped liner". You will not see it moving. They can shift, distort and leak but will not physically Clive up and down in the block.. By someone referring to "slipped" it actually means it has moved from its original position but does not mean it is loose in the block (cannot happen).
I recently completed a complete build with flanged replacement liners in my 2002 d2.
Was ther definite sign of gasket failure? Heads passed leak test and were not excessively warped?
Lots of good information on here
Good luck, keep us informed with your progress!
 

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Discussion Starter · #3 ·
I'll be sure to check the O2 sensor as well as the connector. I know the connector has a good bit of oil on it.

I was sure not to mix up the wires, but I will double check that. I'm wondering if the coil pack could be bad?

I'm not seeing vapor or water coming out the tailpipe, so I imagine the heads and block are good. The machinist said the heads passed the leak test but were off by two-thousandths in a few areas--could that have caused the original head gasket to blow? The old head gasket was blown clean through the ring toward the exhaust side on Cylinder 4.

What about this knock sensor code? Would that be a result of the misfire or could it be a cause?

What about timing? Is it possible for it to have jumped a tooth at any point? I didn't mess with the chain when I had it torn down.

Thanks!
 

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The Old Guy
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redtruck12, while i agree with 99% of what you say, I have to disagree with the liner issue. It is completely possible for the liner to move up and down on an engine that has had a liner slip. When the liner does slip and moves, it makes a ticking sound from the liner hitting the fire ring on the head gasket. It will damage the head gasket. I happen to be reading another post on disco web and found some good reads.
https://discoweb.org/forums/showthread.php?t=74254
Rock on Brother.
 

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Discussion Starter · #5 ·
Update: I unplugged the O2 sensor that was throwing the code while the Rover was running and the engine performance didn't change one bit. It's the pre-cat sensor on the passenger side. Guessing that's part of the problem.
 

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It is completely possible for the liner to move up and down on an engine that has had a liner slip. When the liner does slip and moves, it makes a ticking sound from the liner hitting the fire ring on the head gasket. It will damage the head gasket.
https://discoweb.org/forums/showthread.php?t=74254
Rock on Brother.
Agree with The Old Guy here. They most certainly can they most certainly do move. I have painful personal experience here. :frown
 

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You mentioned oil and crud in the o2 connector. I would deal with that before anything else. You need to get it reading/ working correctly.
Clean the connector, replace the sensor, whatever it takes !
 

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This might be/sound really stupid, but did you check your throttle cables were snugly fastened to as close as their original location as possible when removed and then reinstalled? I have seen a few people whom have done head gaskets in the past over look this and have had sluggish performance as there was major slack in the cables. I would also check the Resistance on all your plug wires, even if new, they can come from factory defective. I had this case with some brand new 8mm sti's. Many don't but I do, add dielectric grease to the inside of the boots and on the outside of the ceramic section of the plugs, never place grease directly on the terminals.

Sometimes it can be the little things.
 
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