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Discussion Starter · #1 ·
Ok. So I purchased my 2001 Disco 2 weeks ago. I felt that it had a misfire while test driving but it wasn't triggering the SES light. I started with the obvious, Magnecor wires and Bosch Platinum plugs. There was the slightest improvement if any...

The misfire is only noticeable when I punch the accelerator or I get above ~2250 RPMs. It's like she has no ass. Well, she has an ass but it takes her quite a bit to get going. To put it simply, rough acceleration. What are the next few measures that I should take???? Will it throw a code with no SES light? I would like to know which one is misfiring so that I can get a better idea as to what the culprit is. Thanks guys!
 

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First question- does your SES light work?

Turn the key to "ON" but don't start the engine. Wouldn't be the first time a seller popped the bulb out. You can always swing buy the parts store and have them hook up a code scanner.

If you were getting a misfire it would set a code. A bad one will give you the blinking light.

The Discovery is alot heavier than it looks and that 4 liter pushrod motor isn't the same as a modern OHC 4 liter. They don't move briskly, if you know what I mean.
 

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X2 on the engine light and codes..
Otherwise first thing that comes to mind is possibly and airflow sensor problem?...
 

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Ok. So I purchased my 2001 Disco 2 weeks ago. I felt that it had a misfire while test driving but it wasn't triggering the SES light. I started with the obvious, Magnecor wires and Bosch Platinum plugs. There was the slightest improvement if any...

The misfire is only noticeable when I punch the accelerator or I get above ~2250 RPMs. It's like she has no ass. Well, she has an ass but it takes her quite a bit to get going. To put it simply, rough acceleration. What are the next few measures that I should take???? Will it throw a code with no SES light? I would like to know which one is misfiring so that I can get a better idea as to what the culprit is. Thanks guys!
I can say that I had rough acceleration with a slight misfire for about 2-weeks and didn't get a light or fault code. I found a faulty plug wire so replaced the whole set and the plugs too. That fixed it but long story short, my bro helped me reassemble and left 2 of the 4 bolts out on the coil pack mounting bracket at the very back so after the 1st day I got a really bad misfire, Check-Engine lamp and misfire fault codes because the coil packs weren't completely secured so I know that the lamps and ECU were all in working order the whole time but the original problem wasn't significant enough for the system to pick up on, even though it existed. Does yours bog-down, or does it feel more like a skip? Because when I had that problem with my wire, to me it felt like a skip or stutter at 2-2.5K RPM (like accelerating onto the highway) so I was diagnosing it as a transmission shudder. I did a couple of trans fluid and filter changes before I really started pulling plugs and wires because I had no fault codes and it was that 1 blip in a specific RPM range.
 

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Discussion Starter · #5 ·
The SES does work and I did run by AutoZone to have them run the code scanner on it. Nothing. It may not be a misfire (maybe the stutter that Chubb878 is referring to). I know that it is heavy but it just seems like something isn't right. I ran some well-reviews fuel system cleaner through it and it MAY have improved but only a bit. I will check the back of the coil packs but they seemed fine when I changed the plugs and wires. Any clues after that if no codes are coming up?
 

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You can start throwing parts at it, or you can wait until it gets worse- which most likely if it's an engine miss it will.

If you had a hard misfire under full acceleration that you felt and significantly affected acceleration, it's unlikely that it wouldn't be setting a code. I bought a parts truck this summer that had compression in the 80's and one very low cylinder and it didn't run poorly or jerk. It did have a light and when you got on it, it would blink.

I would do a compression test to see if you have any mechanical issues. Then I would pull the valve covers and put a dial indicator on the rockers and see if you lost a cam lobe or two. Or you may just want to seek professional intervention.
 

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I had a funny thing happen (similar as I recall) a couple years ago, dirty / oil contaminated o2 sensor connector.

I gues the possibilities are numerous.
 

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A bad(not completely failed) MAF will not trigger the MIL warning(SES as you named it) and might not even throw a fault code as long as the readings are between 0.2 and 4.8V but it can give erratic readings within this range and mix up the management...actually this is valid for most of the sensors, the MIL will come on if the sensor is open or short circuit or the reading exceeds the accepted range. A live data session on the road with scanner would be good to see all the sensor's behaviour while the symptom occurs.
 

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Like he said. It could be a sensor, vacuum leak, valve train, any of that including ignition like plug/wire faulty out of the box, a coil pack on the way out, a coil pack that is not grounded. make sure that all 4 bolts are securing the coil bracket to the engine.
 

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Disco Chai
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I want to put Magnacor and plus 4's on my 2000Discovery2 but when I go to purchase there are multiple numbers to choose from! Anyone know the specific numbers even the bosch platinum plus 4 have multiple numbers to choose from.some advice what Help me.also read somewhere that you can request custom ignition wire length and should inorder to have somePlay/give?anyway,how can you tell if u have a misfire (symptoms)other then code.u mentioned "feeling"it.just asking,i love to learn .i can feel every vibration and if I was alittle more knowledgeable bet I do wounders.its like She is talking to me,i just need to learn Her language, lol.1?
 

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Daniel -

In addition to the MAF I would wonder about the integrity of the Crankshaft Position Sensor.

The CPS will not usually go much past 100K miles before failing.
The usual symptom is the truck just stops running and does not set a code.
This condition is very much temperature dependent - showing up when the sensor becomes heated in use. It is possible that yours may be weak - even though the engine is not cutting out completly.
If yours is over 100k it may well be playing into your situation.

Good luck resolving this issue.

Edit:

Just noticed I have responded to an older post that has been hijacked!

No hurt, no foul!
 
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