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Discussion Starter · #1 ·
I recently replaced the head gaskets on my 2004 LR Discovery. The passenger side HG was blown.
I installed all new gaskets, new Bosch platinum plugs, new NGK wires, new air filter.
Valves were lapped.
All cylinders have 120PSI compression (low, but consistent).
Vacuum reader shows 18in/hg at idle

Here's the problems:
Rough idle
Sluggish acceleration even at high RPMs (I believe I need to top off the trans fluid because some drained out when I pulled the trans coolant line)
Tensioner pulley is jumping
Ticking noise coming from rear passenger head (top end, maybe a lifter or rocker arm?)
Spark plugs foul up with dry black soot very quickly

And the CODES (some of which are inconsistently displaying):
P0300
P0302
P0303
P0305
P0308
P1300
P0413
P1319
P0130
P1129

Note: after resetting the ECU several times, the P0303 and P0305 codes consistently display first, while others don't always show...and the HG was blown on cylinder 3, not sure if there's a correlation?

What does everyone think? I'm at a loss and can't afford to throw parts at it. Basically the codes are summarized as Misfires, O2 sensors, SAI, (and earlier I was even getting a knock sensor code).

Thanks
Aaron
 

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Easy One?

Tensioner pulley is jumping
You are likely seeing the tensioner assembly jerk/jump not the pulley, they do go south doing that occasionally and are inexpensive/easy to R&R. Recently did mine after hearing a tapping sound and nearby noticed tensioner jerking at idle.

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Discussion Starter · #5 ·
You are likely seeing the tensioner jerk/jump not the pulley, they do go south doing that occasionally and are inexpensive/easy to R&R. Recently did mine after hearing a tapping sound and in same location notice tensioner jerking at idle.
Sorry, I meant to say the tensioner is jumping. But it's not too major of a concern and I wouldn't think it would cause the rough idle/poor performance.
 

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Discussion Starter · #7 ·
Check the routing of the plug wires again. You realize that the diagram showing the coils and wires are backward. They are as seen from the inside of the cabin.
I plan to do that again. I was careful to orient myself properly when initially installing them, but there's a chance I still goofed up.

What about injectors? Could they be at fault? Guess there's about a hundred other possible causes..
 

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Were the spark plug wires properly connected? Make sure all 4 bolts are securing the coil packs. I know from experience that misfires will occur if you miss the bottom 2 bolts that secure them to the engine. Vibration and contact with the bulkhead will screw up the HT leads in a bad way. Intake plenum and valley gasket also raises suspicions if you did not properly install a brand new one after thoroughly cleaning contact surfaces of the parts, themselves. Re-torque the 6 bolts securing that plenum another smidge. I would then be checking the PCV system. 1 hose from DS valve cover to throttle intake, and other hose from PS VC to intake plenum. Something must be crossed-up. Did you take pics and/or label some of the stuff disconnected during the repair? The flex tube you are needing can be found anywhere. You could have had that part in 1 day. About 10 sources come to mind if you need pointing in the proper direction on that. I think that your biggest issue is going to be something with the ignition system. most of the faults and noises are the result of the engine unable to fire on any of the cylinders
 

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Longshot To Consider

I meant to say the tensioner is jumping. But it's not too major of a concern and I wouldn't think it would cause the rough idle/poor performance.
That's why it's the easy one on list.

Since you did notice it's jumping would recommend you check all accessory/idler pulleys for drag/bearing wear with belt off. Could be a good tensioner telling you something and costs nothing except a little time.

I saw a CES light go away and noticed a significant increase in performance replacing the bad a/c clutch on a lady friend's 1998 F-150 this summer. Clutch pulley bearings apparently had been wearing/failing for some time causing too much load/drag on engine causing CES. Bearing came apart and then seized while simultaneously shutting engine down/shredding.

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Just a thought on the ticking noise; when I re-did my heads, I didn't seat one of the valve springs properly which caused the spring to bottom out prematurely and broke the rocker arm. Along with the tick, it threw mis-fire codes. When I pulled the valve cover and figured out what caused it, I just pushed the spring into it's seat with a big screwdriver, reassembled with a new rocker and, guess what? No more tick or codes! ..just another possibility to consider..
 

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Discussion Starter · #11 ·
Fixed!!

Alright so it turns out plug wires 3 and 5 were mixed up. I looked back at the diagram I used and it was for a Discovery 1, not a 2.

While I had the intake off, I decided to investigate the ticking noise coming from the back of the passenger valve cover. Nothing was broken or out of place, but I think during the HG repair I switched the two rear push rods. So I switched them again (in the process, dropped one through the hole toward the lifters/cam and ended up having to take off the intake, injectors, etc, to get to it...that's my usual luck).

Once back together, I initially turned it on to find out it still had a rough idle. Turned out plug wire 7 was ripped out of the connector boot on the coil side (probably from all the stretching around to get the coils back in place). I replaced it with an old, intact wire.

I made sure to bolt in the coils at all 4 points, as suggested.

Second start, it ran rough for a little bit, but smoothed out nicely. No more misfire codes!!

Lesson learned: double and triple check plug wire connections, and more importantly the compatibility of the diagram you're using! Interestingly, the jumping tensioner seemed to go away. And the dry ticking noise is now much softer and muffled for some reason.

Thanks to everyone for the advice. I wish I could say this was a true puzzle I solved, but turned out to be a reminder to keep the basics in check.
 
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