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Discussion Starter #1
I have a 96 RR 4.0SE.

You can read about my problems here: http://www.rangerovers.net/forum/viewto ... ?p=418#418

My new question is relating to the coils. It is my understanding that this engine has 4 individual coils. Each coil powers two cylinders, right?

So if I have a misfire on Cyl 1, but no other Cylinder is having problems, that would rule out the coil, correct?

TIA

dave
 

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638 Posts
Good point Dave -- that would appear to be right I suppose, although not completely certain as that coil may fail intermittently one way and not the other??? Anyhow maybe you sould check the spark plug lead (and the plug). Maybe someone else will have some other ideas!

Cheers

John
 

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FOUNDING MEMBER
1995-2002 Range Rover P38A
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96 Posts
Right Dave,

After reading your other thread I would be considering the sticky exhaust valve dilema. As the knock sensor can tell which of the two cylinders is suppose to be firing on a compression stroke and cylinder 1 is the culpret here, I would get a compression test guage and see how it compares with the rest of the cylinders on that side of the engine. The combination of codes is very similar to what my wifes 97 Discovery SE did two years ago on cylinder 4 or 5 I think it was. The older 4.0's of mid to late 90's vintage have a tendency for the exhuast valve stem to become carbon fouled which then causes it to stick in the vale guide thus allowing the compression strokes air and fuel mixture to be expelled into the exhaust manifold which still is ignited but left to run like this will burn the valve and obviously produce appaulling gas milege, not to mention the mis fire codes. The P1316 (Excessive misfire) is more than likely the oxegen sensors going kryky whats all this raw unburned fuel doing down here.

What is the engines milege? Have you tried to run any chem tool into the intake to clean the engine? Are you cheaking the spark with a spark plug in the end of the wire and touching a good ground on the engine? You need the load which the plug provides to really know if the coil is good or not.
 

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Discussion Starter #4
I've got 88k on the engine. Gas milage runs at about 13.5mpg but I live in the Ozark Mountains and I'm always going up hills or down hills.

I performed a Gum-Out treatment that consists of a bottle of their cleaner in your fuel tank and you drip in some potent cleaner through a vacuum line directly into the intake. It made a big difference, and the check engine light went off for 2 days.

It's back on now and the stumbling is a bit more frequent. I'll have new plug wires on it tomorrow and see if that clears anything up.

I'm really hoping its not a valve problem. If it is, is it within the scope of an "above average shade tree mechanic"?
 

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1995-2002 Range Rover P38A
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96 Posts
Well Dave,

It look as though your hitting all the right stuff. As far as spark plug wires I would highly recommend Magnacor. OffRoadTuff.com has them for our Rovers. The wires my be it at 88K I usually make a habit of replacing them at 50K. The four coil setup fires both plugs on that coil. One is on a compression stroke the other isn't but is sparked just the same. This means our ignition wires and plugs see double the voltage enrgy for a given set of miles.

I cleaned out the 97 Discovery's intake when I replaced the valley gakett as the water gallery was leaking at the back between the head and intake manifold. It wasn't too long after that when the codes and stuck valve issue came to be. You may be playing the game here with your Rangie along the same lines. The fix for the vales is to replace them with unshrouded ones and lap the seats with some grinding paste. But that was on a Discovery with just barely 40K on it. So at 88K it might be head job time. Do the ends of the heads weep anti-freeze at the head gasket yet?
 

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Discussion Starter #6
The head-gaskets are fine. Everything works fine, less the check engine light.

And now I have less power and more stuttering. Good thing my wires come in tomorrow.

I didn't get Magnacor as I need them NOW so I had to get the O'reiley's replacement.
 

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1995-2002 Range Rover P38A
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Ok Dave,

Lets hope it is the wires. When you place the new ones into the wire guide clips, pay particular attention to the wires near were the end caps connect to the plugs. The Magnacor insulation is so long that as the kink in the molded end directs the wire up along side the valve cover the molded part is long enough to buffet the edge of the valve cover and provide additional anti-arching protection. This has been a problem on my wifes Discovery and found that the OEM and All Makes wires I repalced them with will arch to this edge of the valve cover right were the wire feeds into the molded boot for the spark plugs connection. You might even apply some silicon gasket maker around the O'reiley's replacement wires as the arching was so bad on the orginal wires that the wire had burned the conductor and litterally severed the insulation about a 1/4 inch down inside the molded boot. Quite shocking it was to realize this occasion was indeed part of the course in Land Rover ownership. When I discovered this the wire came clean out of the boot when I tugged the boot from the plug.
 

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Discussion Starter #8
New plug wires have been fitted
Spark plugs have about 7k on them
Fuel injector treatment performed.

CHECK ENGINE LIGHT IS STILL ON.

the codes are still P0301 (misfire on cyl 1) and p1316 (excessive misfire)

What else can I check?
 

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Discussion Starter #10
I have a new-to-me coil from Car Cannibal on the way. If that doesn't fix it, here my remaining options:

Crankshaft Position Sensor
Compression test = valve possibly

What does it typically run to replace a valve?

Dave
 

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Discussion Starter #12
Slight update:

Now my check engine light comes on, I only get one code: P1316, Excessive Misfire Emissions Fault.

No specific cylinder codes, just that one code....
 

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Discussion Starter #13
Some updates:

Today I removed all plugs, wires, and the coils. The connections to the coils (the two small wires held by a nut) where a bit dirty. I cleaned those up really well, then I preformed a compression test. I got 150 psi on every cylinder except #6 where I got 138 psi. I have heard that if your lowest compression is within your highest, then everything is ok. I hope this is true.

The plugs were pretty fouled up (I think from a previous fuel injection cleaning) so I cleaned them then I added some Seafoam to the gas tank and poured some in the vacuum line leading to the intake.

Now I have a horrible idle sitting at 300 rpm's and it still stutters and the check engine light continues to come back with P1316.

Still stumped!!!!!!
 

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Discussion Starter #14
I am still getting a check engine light, but the only code I am getting is a P1316. The idle is USUALLY great, but recently its been shuddering at idle and low speeds. If I hit the accelerator, it smoothes out, but as soon as I let off, I get the shudder. If I come to a stop the engine sounds like it wants to die. Low speeds and idle are not very smooth.

I also hooked up a vacuum gauge to my manifold where the fuel pressure regulator normally supplies to. I did get some needle movement at idle. I drove around and when I hit the gas the needle dropped to 5"Hg and set there like a rock then when I let off, it hit back to 23"Hg and started to shake (it literally looked like the needle was trying to dance).

Does this 100% mean a sticking valve? Anything else I can do to either rule out the valve, or specifically test that theory?

TIA
 

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1995-2002 Range Rover P38A
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Dave did you run the compression test on the cylinders yet? How old are the O2 sensors? When didyou replace the fuel filter? I caught some of your messages on Motorcars Limited.
 

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Discussion Starter #16
Compression test: 150 psi on all cylinders with 138 psi on #6.

However, I think I just found the culprit. Prepare for long writeup:

When a valve sticks it usually creates a suction at the exhaust pipe. You can test this via the "dollar bill test". Hold a dollar bill up to your exhaust pipe and see if it gets sucked back in. Well mine didn't. I was pretty confident that I didn't have the valve problem, but just didn't know where to go.

I did some research at Motorcars LTD forums and found a thread on a guy who had the exact same problems I was having. His turned out to be a bent Crankshaft Position Sensor. Well I finally found my CKS (who decided to mount that dude there, by the way). I gave the connectors a quick yank, nothing was obvious. I went to start my car and it wouldn't start up. It would just sit and crank. So it hit me: my CKS. I rechecked it and the cable was completely detached from its connector. Upon closer research the portion of the connector from my main wireloom under the Ignition coils did not have the small metal retaining band. I removed the CKS, reconnected them and secured the setup with Zip-Ties then mounted it back to the engine.

Viola: no rough idle. No studdering. No misses.

Very interesting . . .
 

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Discussion Starter #18
Me too. I was dreading valves.

Motorcars has a very nice forum. I think this one will evolve into a similar wealth of information.
 

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2002-2005 Range Rover MkIII / L322
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davebl said:
I did some research at Motorcars LTD forums and found a thread on a guy who had the exact same problems I was having. His turned out to be a bent Crankshaft Position Sensor. Well I finally found my CKS (who decided to mount that dude there, by the way).
The sensor has a thin probe - about 1/16" 1.6mm diameter and would be very easy to bend if it was in place when the auto trans flywheel/flex plate was replaced.

I didn't fit it to my block until I'd fitted the flywheel. It's easy to get to when the exhaust manifolds aren't there :)

Ron
 
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